The circular chromatic number and the fractional chromatic number are two generalizations of the ordinary chromatic number of a graph. We say a graph G is star extremal if its circular chromatic number is equal to its...The circular chromatic number and the fractional chromatic number are two generalizations of the ordinary chromatic number of a graph. We say a graph G is star extremal if its circular chromatic number is equal to its fractional chromatic number. This paper gives an improvement of a theorem. And we show that several classes of circulant graphs are star extremal.展开更多
Consider the Teichmuller mapping f associated with in the unit disc D and the class of all quasiconformal mappings in D with the boundary values of f. For a special holomorphic function, the present paper gives the ne...Consider the Teichmuller mapping f associated with in the unit disc D and the class of all quasiconformal mappings in D with the boundary values of f. For a special holomorphic function, the present paper gives the necessary and sufficient condition on, such that f is uniquely extremal among the class. Further, for a general holomorphic function, the anthors suggest the models of the best possible growth conditions on, such that f is extremal or uniquely extremal among the class respectively.展开更多
It is proved that if f is a Teichmuller self-mapping of the unit disk with a holomorphic quadratic deferential and satisfies the growth condition m(ψ，r)= o((1 -r)-), r→1, for any s>1, then f is extremal, and the...It is proved that if f is a Teichmuller self-mapping of the unit disk with a holomorphic quadratic deferential and satisfies the growth condition m(ψ，r)= o((1 -r)-), r→1, for any s>1, then f is extremal, and there exists a sequence {tn}, 0<tn<1, /lim, tn =1, such that {(tnz)} is a Hamilton sequence. It is the precision of a theorem of Reich-Strebel in 1974, and gives a fairly satisfactory answer to a question of Reich in 1988.展开更多
Given a compact Riemann surface S with finitely many punctures, in this paper we obtain a new extremality property of a Jenkins-Strebel differentialψon S. As a consequence, we obtain the solutions of several kinds of...Given a compact Riemann surface S with finitely many punctures, in this paper we obtain a new extremality property of a Jenkins-Strebel differentialψon S. As a consequence, we obtain the solutions of several kinds of moduli problems on 5.展开更多
A universal relation between the leading correction to the entropy and extremality was proposed in the work of Goon and Penco.In this paper,we extend this work to massive gravity and investigate thermodynamic extremal...A universal relation between the leading correction to the entropy and extremality was proposed in the work of Goon and Penco.In this paper,we extend this work to massive gravity and investigate thermodynamic extremality relations in a topologically higher-dimensional black hole.A rescaled cosmological constant is added to the action of the massive gravity as a perturbative correction.This correction modifies the extremality bound of the black hole and leads to shifts in the mass,entropy,etc.Regarding the cosmological constant as a variable related to pressure,we obtain the thermodynamic extremality relations between the mass and entropy,pressure,charge,and parameters ci by accurate calculations.Finally,these relations are verified by a triple product identity,which shows that the universal relation exists in black holes.展开更多
In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields...In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields can slightly change the cluster-decay half-life by affecting the penetration probability within a narrow range.Subsequently,we discuss the correlation between the change rate of the penetration probability and the tunneling path.The results indicate that for different parent nuclei emitting the same cluster,nuclei with longer tunneling paths are more easily affected by the laser fields.The shell effect on this correlation is also observed.In addition,the impact of laser fields on the penetration probability in any direction is investigated.展开更多
Objective:To analyze the clinical application value of autologous periosteum graft combined with platelet-rich plasma(PRP)in the treatment of long bone fractures in the extremities.Methods:A total of 40 patients with ...Objective:To analyze the clinical application value of autologous periosteum graft combined with platelet-rich plasma(PRP)in the treatment of long bone fractures in the extremities.Methods:A total of 40 patients with long bone fractures in the extremities admitted to Santai Hospital Affiliated to North Sichuan Medical College from January 2023 to January 2025 were included,including cases of upper extremity forearm fractures and lower extremity femoral and tibial fractures.The patients were evenly divided using a random number table,with the control group undergoing open reduction and internal fixation(ORIF)combined with autologous periosteum graft,and the observation group undergoing ORIF,autologous periosteum graft,and PRP injection.Surgical indicators,complication rates,excellent fracture healing rates,functional satisfaction,and joint range of motion were compared between the two groups.Results:The surgical indicators in the observation group were similar to those in the control group(p>0.05).The complication rate in the observation group was lower than that in the control group,while the excellent fracture healing rate and functional satisfaction were higher in the observation group(p<0.05).Conclusion:Autologous periosteum graft combined with PRP technology is safe and reliable for the treatment of long bone fractures in the extremities,with satisfactory clinical outcomes.展开更多
Nail changes following upper extremity transplantation(UET)cannot be overlooked as they possess diagnostic and prognostic relevance in allotransplantation of upper limbs.This comprehensive review explores nail and nai...Nail changes following upper extremity transplantation(UET)cannot be overlooked as they possess diagnostic and prognostic relevance in allotransplantation of upper limbs.This comprehensive review explores nail and nail bed related changes encountered in UET recipients in the literature.The differential diagnosis of nail abnormalities in UET includes a wide range of systemic,local and iatrogenic conditions other than immune responses to the allograft.It requires interdisciplinary evaluation by primary transplant surgeons,pathologists,dermatologists and immunologists.The possible underlying mechanisms of nail pathology in UET and the management are discussed.It also underscores the importance of onychodystrophy and need for timely intervention and to improve outcomes in UET recipients.展开更多
Global warming and socioeconomic development are expected to exacerbate human exposure to heat stress,but the extent and inequality of such changes remain unclear.Here,we quantified the future population exposure to h...Global warming and socioeconomic development are expected to exacerbate human exposure to heat stress,but the extent and inequality of such changes remain unclear.Here,we quantified the future population exposure to heat stress(PEHS)under different Shared Socioeconomic Pathways(SSPs)and Representative Concentration Pathways(RCPs)scenarios using a novel decomposition framework that separates the contributions of climate change,population change,and their interaction.Results show that global PEHS will increase substantially during the 21st century,with low-latitude regions experiencing the largest absolute increases,and high-latitude regions facing the largest relative increases.Globally,projected increases in PEHS under SSP3-7.0 are roughly three times those under SSP1-2.6,with low latitudes contributing about 70%-75%of the global total.SSP1-2.6 most effectively limits future heat exposure,with the highest risks in low-latitude developing regions,underscoring the need for low-emission pathways and targeted population and urbanization management.The findings highlight the urgent need for both climate mitigation and population adaptation strategies to address the growing and uneven heat exposure risks worldwide.展开更多
The global monsoon system,encompassing the Asian-Australian,African,and American monsoons,sustains two-thirds of the world’s population by regulating water resources and agriculture.Monsoon anomalies pose severe risk...The global monsoon system,encompassing the Asian-Australian,African,and American monsoons,sustains two-thirds of the world’s population by regulating water resources and agriculture.Monsoon anomalies pose severe risks,including floods and droughts.Recent research associated with the implementation of the Global Monsoons Model Intercomparison Project under the umbrella of CMIP6 has advanced our understanding of its historical variability and driving mechanisms.Observational data reveal a 20th-century shift:increased rainfall pre-1950s,followed by aridification and partial recovery post-1980s,driven by both internal variability(e.g.,Atlantic Multidecadal Oscillation)and external forcings(greenhouse gases,aerosols),while ENSO drives interannual variability through ocean-atmosphere interactions.Future projections under greenhouse forcing suggest long-term monsoon intensification,though regional disparities and model uncertainties persist.Models indicate robust trends but struggle to quantify extremes,where thermodynamic effects(warming-induced moisture rise)uniformly boost heavy rainfall,while dynamical shifts(circulation changes)create spatial heterogeneity.Volcanic eruptions and proposed solar radiation modification(SRM)further complicate predictions:tropical eruptions suppress monsoons,whereas high-latitude events alter cross-equatorial flows,highlighting unresolved feedbacks.The emergent constraint approach is booming in terms of correcting future projections and reducing uncertainty with respect to the global monsoons.Critical challenges remain.Model biases and sparse 20th-century observational data hinder accurate attribution.The interplay between natural variability and anthropogenic forcings,along with nonlinear extreme precipitation risks under warming,demands deeper mechanistic insights.Additionally,SRM’s regional impacts and hemispheric monsoon interactions require systematic evaluation.Addressing these gaps necessitates enhanced observational networks,refined climate models,and interdisciplinary efforts to disentangle multiscale drivers,ultimately improving resilience strategies for monsoon-dependent regions.展开更多
1.Introduction In recent years,intensifying climate extremes have triggered a sharp increase in global natural disasters,over 90%attributable to water-related hazards,particularly floods(Hirabayashi et al.,2013).Over ...1.Introduction In recent years,intensifying climate extremes have triggered a sharp increase in global natural disasters,over 90%attributable to water-related hazards,particularly floods(Hirabayashi et al.,2013).Over the past two decades,floods have inundated approximately 2.23 million km2 of land worldwide(Tellman et al.,2021),affecting over 250 million people and causing economic losses exceeding USD 651 billion(Devitt et al.,2023).Recent catastrophic floods in Pakistan,landslides in Indonesia,and dike breaches in China have intensified concerns over the effectiveness of current flood management strategies.展开更多
Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instabili...Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instability,occur frequently in both experimental and operational data.This infrequency causes events to be overlooked by existing prediction models,which lack the precision to accurately predict inclination attitudes in amphibious vehicles.To address this gap in predicting attitudes near extreme inclination points,this study introduces a novel loss function,termed generalized extreme value loss.Subsequently,a deep learning model for improved waterborne attitude prediction,termed iInformer,was developed using a Transformer-based approach.During the embedding phase,a text prototype is created based on the vehicle’s operation log data is constructed to help the model better understand the vehicle’s operating environment.Data segmentation techniques are used to highlight local data variation features.Furthermore,to mitigate issues related to poor convergence and slow training speeds caused by the extreme value loss function,a teacher forcing mechanism is integrated into the model,enhancing its convergence capabilities.Experimental results validate the effectiveness of the proposed method,demonstrating its ability to handle data imbalance challenges.Specifically,the model achieves over a 60%improvement in root mean square error under extreme value conditions,with significant improvements observed across additional metrics.展开更多
An unprecedented extreme gale and dust event struck East Asia during 10-14 April2025.A record-breaking gale swept across most regions of China.It carried large amounts of dust from northern deserts,resulting in nation...An unprecedented extreme gale and dust event struck East Asia during 10-14 April2025.A record-breaking gale swept across most regions of China.It carried large amounts of dust from northern deserts,resulting in nationwide dust weather.Gales affected more than 3.5 million km^(2),and the windspeeds in North China were the strongest in April since 1940(Fig.1a,b).展开更多
Unlike animals, plants cannot move away from unfavorable environments. Instead, they must continuously adjust their growth to external conditions. When the environment is favorable, plants sustain vigorous growth. Con...Unlike animals, plants cannot move away from unfavorable environments. Instead, they must continuously adjust their growth to external conditions. When the environment is favorable, plants sustain vigorous growth. Conversely, when challenged by drought, salinity, temperature extremes, or other stresses, they must rapidly suppress growth to conserve energy and minimize damage. This capacity to switch growth on or off in response to external cues represents one of the most successful adaptive strategies that enables plants to thrive worldwide. A central mediator of this growth suppression is the phytohormone abscisic acid(ABA). Abscisic acid plays pivotal roles in stomata closure, germination inhibition, and root development modulation, thereby orchestrating defense responses under abiotic stresses(e.g., Chen et al., 2020, for a review). For this reason, ABA is often referred to as the“stress hormone” of plants. However,growth arrest is only half of the story. Once environmental conditions improve, plants must promptly resume growth to recover and compete effectively. For survival, the decision of whether“to grow or not to grow” is critical, and yet, the molecular mechanisms that enable plants to toggle this switch have long remained elusive.展开更多
Ensuring reliable power supply in urban distribution networks is a complex and critical task.To address the increased demand during extreme scenarios,this paper proposes an optimal dispatch strategy that considers the...Ensuring reliable power supply in urban distribution networks is a complex and critical task.To address the increased demand during extreme scenarios,this paper proposes an optimal dispatch strategy that considers the coordination with virtual power plants(VPPs).The proposed strategy improves systemflexibility and responsiveness by optimizing the power adjustment of flexible resources.In the proposed strategy,theGaussian Process Regression(GPR)is firstly employed to determine the adjustable range of aggregated power within the VPP,facilitating an assessment of its potential contribution to power supply support.Then,an optimal dispatch model based on a leader-follower game is developed to maximize the benefits of the VPP and flexible resources while guaranteeing the power balance at the same time.To solve the proposed optimal dispatch model efficiently,the constraints of the problem are reformulated and resolved using the Karush-Kuhn-Tucker(KKT)optimality conditions and linear programming duality theorem.The effectiveness of the strategy is illustrated through a detailed case study.展开更多
The construction of lunar bases represents a crucial goal for long-term human residence on the Moon and future deep-space exploration. Vacuum sintering of lunar regolith for in-situ resource utilization(ISRU) is consi...The construction of lunar bases represents a crucial goal for long-term human residence on the Moon and future deep-space exploration. Vacuum sintering of lunar regolith for in-situ resource utilization(ISRU) is considered one of the most feasible strategies for early lunar infrastructure development. However, the extreme temperature fluctuations on the lunar surface pose potential threats to the structural stability of sintered regolith materials. To investigate the mechanical deterioration and damage mechanism of vacuum-sintered lunar regolith under extreme cryogenic-thermal cycling, lunar regolith simulants are used to fabricate specimens through vacuum sintering. A series of cryogenic-thermal cycling tests is designed, combined with uniaxial compression and X-ray CT scanning, to systematically analyze their macro-micro responses. The results show that with increasing extreme cryogenic-thermal cycles, the stress-strain curves evolve from typical brittle failure to quasiductile behavior, with uniaxial compressive strength and elastic modulus decreasing by approximately 33.86% and 61.98%, respectively. CT analyses reveal that the pore structure transforms from isolated pores to connected networks, with the pore volume fraction increasing from 13.33% to 22.64%, and the fractal dimension increases from 2.465 to 2.544, and stabilizes after multiple cycles. A significant negative correlation(R^(2)> 0.96) exists between pore structural complexity and mechanical performance. Based on these findings, a thermal fatigue damage mechanism dominated by thermal stress concentration due to mismatched thermal expansion coefficients among mineral phases is proposed. This study provides scientific insights for the design, durability evaluation, and ISRU-based construction of lunar surface infrastructure.展开更多
As unmanned underwater vehicles (UUVs) are increasingly designed to perform long-duration missions in highly complex and often extreme environments, traditional design methods face significant and growing challenges^(...As unmanned underwater vehicles (UUVs) are increasingly designed to perform long-duration missions in highly complex and often extreme environments, traditional design methods face significant and growing challenges^([1,2]).展开更多
To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) po...To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) pollution control strategies.However,currently widely-used methods,such as statistical models and numerical models,exhibit inherent limitations in identifying OPS in a timely and accurate manner.In this study,we developed a novel approach to identify OPS based on eXtreme Gradient Boosting model,Shapley additive explanation(SHAP)al-gorithm,and volatile organic compound(VOC)photochemical decay adjustment,using the meteorology and speciated pollutant monitoring data as the input.By comparing the difference in SHAP values between base sce-nario and precursor reduction scenario for nitrogen oxides(NO_(x))and VOCs,OPS was divided into NO_(x)-limited,VOCs-limited and transition regime.Using the long-lasting O_(3) pollution episode in the autumn of 2022 at the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)as an example,we demonstrated large spatiotemporal heterogeneities of OPS over the GBA,which were generally shifted from NO_(x)-limited to VOCs-limited from September to October and more inclined to be VOCs-limited at the central and NO_(x)-limited in the peripheral areas.This study developed an innovative OPS identification method by comparing the difference in SHAP value before and after precursor emission reduction.Our method enables the accurate identification of OPS in the time scale of seconds,thereby providing a state-of-the-art tool for the rapid guidance of spatial-specific O_(3) control strategies.展开更多
In this study,three specific scenarios of a novel accelerator light source mechanism called steady-state microbunching(SSMB)were studied:longitudinal weak focusing,longitudinal strong focusing,and generalized longitud...In this study,three specific scenarios of a novel accelerator light source mechanism called steady-state microbunching(SSMB)were studied:longitudinal weak focusing,longitudinal strong focusing,and generalized longitudinal strong focusing(GLSF).At present,GLSF is the most promising method for realizing high-power short-wavelength coherent radiation with mild requirements on modulation laser power.Its essence is to exploit the ultrasmall natural vertical emittance of an electron beam in a planar storage ring for efficient microbunching formation,like a partial transverse-longitudinal emittance exchange in the optical laser wavelength range.Based on an in-depth investigation of related beam physics,a solution for a GLSF SSMB storage ring that can deliver 1 kW average-power EUV light is presented.The work in this paper,such as the generalized Courant–Snyder formalism,analysis of theoretical minimum emittances,transverse-longitudinal coupling dynamics,and derivation of the bunching factor and modulation strengths for laser-induced microbunching schemes,is expected to be useful not only for the development of SSMB but also for future accelerator light sources in general that demand increasingly precise electron beam phase space manipulations.展开更多
NH_(4)V_(4)O_(10)(NVO)is considered a promising cathode material for aqueous zinc-ion batteries due to its high theoretical capacity.However,its practical application is limited by irreversible deamination,structural ...NH_(4)V_(4)O_(10)(NVO)is considered a promising cathode material for aqueous zinc-ion batteries due to its high theoretical capacity.However,its practical application is limited by irreversible deamination,structural collapse,and sluggish reaction kinetics during cycling.Herein,K+and C_(3)N_(4)co-intercalated NVO(KNVO-C_(3)N_(4))nanosheets with expanded interlayer spacing are synthesized for the first time to achieve high-rate,stable,and wide-temperature cathodes.Molecular dynamics and experimental results confirm that there is an optimal C_(3)N_(4)content to achieve higher reaction kinetics.The synergistic effect of K^(+)and C_(3)N_(4)co-intercalation significantly reduces the electrostatic interaction between Zn^(2+)and the[VOn]layer,improves the specific capacity and cycling stability.Consequently,the KNVO-C_(3)N_(4)electrode displays outstanding electrochemical performance at room temperature and under extreme environments.It exhibits excellent rate performance(228.4 m Ah g^(-1)at 20 A g^(-1)),long-term cycling stability(174.2 m Ah g^(-1) after 10,000 cycles at 20 A g^(-1)),and power/energy density(210.0 Wh kg^(-1)at 14,200 W kg^(-1))at room temperature.Notably,it shows remarkable storage performance at-20℃(111.3 m Ah g^(-1)at 20 A g^(-1))and 60℃(208.6 m Ah g^(-1)at 20 A g^(-1)).This strategy offers a novel approach to developing high-performance cathodes capable of operating under extreme temperatures.展开更多
文摘The circular chromatic number and the fractional chromatic number are two generalizations of the ordinary chromatic number of a graph. We say a graph G is star extremal if its circular chromatic number is equal to its fractional chromatic number. This paper gives an improvement of a theorem. And we show that several classes of circulant graphs are star extremal.
文摘Consider the Teichmuller mapping f associated with in the unit disc D and the class of all quasiconformal mappings in D with the boundary values of f. For a special holomorphic function, the present paper gives the necessary and sufficient condition on, such that f is uniquely extremal among the class. Further, for a general holomorphic function, the anthors suggest the models of the best possible growth conditions on, such that f is extremal or uniquely extremal among the class respectively.
基金the National Natural Science Foundation of China!(No.19531060), the DoctoralProgram Fundation of the Ministry of Education o
文摘It is proved that if f is a Teichmuller self-mapping of the unit disk with a holomorphic quadratic deferential and satisfies the growth condition m(ψ，r)= o((1 -r)-), r→1, for any s>1, then f is extremal, and there exists a sequence {tn}, 0<tn<1, /lim, tn =1, such that {(tnz)} is a Hamilton sequence. It is the precision of a theorem of Reich-Strebel in 1974, and gives a fairly satisfactory answer to a question of Reich in 1988.
基金This work was partially supported by the National Natural Science Foundation of China (Grant No. 10501046).
文摘Given a compact Riemann surface S with finitely many punctures, in this paper we obtain a new extremality property of a Jenkins-Strebel differentialψon S. As a consequence, we obtain the solutions of several kinds of moduli problems on 5.
基金Supported by NSF C(11875196,11375121,11205125,11005016)Xihua University Talent Project(Z201021)。
文摘A universal relation between the leading correction to the entropy and extremality was proposed in the work of Goon and Penco.In this paper,we extend this work to massive gravity and investigate thermodynamic extremality relations in a topologically higher-dimensional black hole.A rescaled cosmological constant is added to the action of the massive gravity as a perturbative correction.This correction modifies the extremality bound of the black hole and leads to shifts in the mass,entropy,etc.Regarding the cosmological constant as a variable related to pressure,we obtain the thermodynamic extremality relations between the mass and entropy,pressure,charge,and parameters ci by accurate calculations.Finally,these relations are verified by a triple product identity,which shows that the universal relation exists in black holes.
基金supported in part by the National Natural Science Foundation of China(Nos.12175100 and 11975132)the Construct Program of the Key Discipline in Hunan Province+5 种基金the Research Foundation of Education Bureau of Hunan Province,China(Nos.21B0402,18A237,22A0305)the Natural Science Foundation of Hunan Province,China(No.2018JJ2321)the Innovation Group of Nuclear and Particle Physics in USCthe Shandong Province Natural Science Foundation,China(No.ZR2022JQ04)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(No.2019KFZ10)the Hunan Provincial Innovation Foundation for Postgraduate(No.CX20251453)。
文摘In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields can slightly change the cluster-decay half-life by affecting the penetration probability within a narrow range.Subsequently,we discuss the correlation between the change rate of the penetration probability and the tunneling path.The results indicate that for different parent nuclei emitting the same cluster,nuclei with longer tunneling paths are more easily affected by the laser fields.The shell effect on this correlation is also observed.In addition,the impact of laser fields on the penetration probability in any direction is investigated.
文摘Objective:To analyze the clinical application value of autologous periosteum graft combined with platelet-rich plasma(PRP)in the treatment of long bone fractures in the extremities.Methods:A total of 40 patients with long bone fractures in the extremities admitted to Santai Hospital Affiliated to North Sichuan Medical College from January 2023 to January 2025 were included,including cases of upper extremity forearm fractures and lower extremity femoral and tibial fractures.The patients were evenly divided using a random number table,with the control group undergoing open reduction and internal fixation(ORIF)combined with autologous periosteum graft,and the observation group undergoing ORIF,autologous periosteum graft,and PRP injection.Surgical indicators,complication rates,excellent fracture healing rates,functional satisfaction,and joint range of motion were compared between the two groups.Results:The surgical indicators in the observation group were similar to those in the control group(p>0.05).The complication rate in the observation group was lower than that in the control group,while the excellent fracture healing rate and functional satisfaction were higher in the observation group(p<0.05).Conclusion:Autologous periosteum graft combined with PRP technology is safe and reliable for the treatment of long bone fractures in the extremities,with satisfactory clinical outcomes.
文摘Nail changes following upper extremity transplantation(UET)cannot be overlooked as they possess diagnostic and prognostic relevance in allotransplantation of upper limbs.This comprehensive review explores nail and nail bed related changes encountered in UET recipients in the literature.The differential diagnosis of nail abnormalities in UET includes a wide range of systemic,local and iatrogenic conditions other than immune responses to the allograft.It requires interdisciplinary evaluation by primary transplant surgeons,pathologists,dermatologists and immunologists.The possible underlying mechanisms of nail pathology in UET and the management are discussed.It also underscores the importance of onychodystrophy and need for timely intervention and to improve outcomes in UET recipients.
基金funded by National Natural Science Foundation of China(Grant No.42271273)Swedish Research Council(VR:2021-02163).
文摘Global warming and socioeconomic development are expected to exacerbate human exposure to heat stress,but the extent and inequality of such changes remain unclear.Here,we quantified the future population exposure to heat stress(PEHS)under different Shared Socioeconomic Pathways(SSPs)and Representative Concentration Pathways(RCPs)scenarios using a novel decomposition framework that separates the contributions of climate change,population change,and their interaction.Results show that global PEHS will increase substantially during the 21st century,with low-latitude regions experiencing the largest absolute increases,and high-latitude regions facing the largest relative increases.Globally,projected increases in PEHS under SSP3-7.0 are roughly three times those under SSP1-2.6,with low latitudes contributing about 70%-75%of the global total.SSP1-2.6 most effectively limits future heat exposure,with the highest risks in low-latitude developing regions,underscoring the need for low-emission pathways and targeted population and urbanization management.The findings highlight the urgent need for both climate mitigation and population adaptation strategies to address the growing and uneven heat exposure risks worldwide.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0608904)the International Partnership Program of the Chinese Academy of Sciences(Grant Nos.060GJHZ2023079GC and 134111KYSB20160031)+1 种基金supported by the Office of Science,U.S.Department of Energy(DOE)Biological and Environmental Research as part of the Regional and Global Model Analysis program area through the Water Cycle and Climate Extremes Modeling(WACCEM)scientific focus areaoperated for DOE by Battelle Memorial Institute under contract DE-AC05-76RL01830。
文摘The global monsoon system,encompassing the Asian-Australian,African,and American monsoons,sustains two-thirds of the world’s population by regulating water resources and agriculture.Monsoon anomalies pose severe risks,including floods and droughts.Recent research associated with the implementation of the Global Monsoons Model Intercomparison Project under the umbrella of CMIP6 has advanced our understanding of its historical variability and driving mechanisms.Observational data reveal a 20th-century shift:increased rainfall pre-1950s,followed by aridification and partial recovery post-1980s,driven by both internal variability(e.g.,Atlantic Multidecadal Oscillation)and external forcings(greenhouse gases,aerosols),while ENSO drives interannual variability through ocean-atmosphere interactions.Future projections under greenhouse forcing suggest long-term monsoon intensification,though regional disparities and model uncertainties persist.Models indicate robust trends but struggle to quantify extremes,where thermodynamic effects(warming-induced moisture rise)uniformly boost heavy rainfall,while dynamical shifts(circulation changes)create spatial heterogeneity.Volcanic eruptions and proposed solar radiation modification(SRM)further complicate predictions:tropical eruptions suppress monsoons,whereas high-latitude events alter cross-equatorial flows,highlighting unresolved feedbacks.The emergent constraint approach is booming in terms of correcting future projections and reducing uncertainty with respect to the global monsoons.Critical challenges remain.Model biases and sparse 20th-century observational data hinder accurate attribution.The interplay between natural variability and anthropogenic forcings,along with nonlinear extreme precipitation risks under warming,demands deeper mechanistic insights.Additionally,SRM’s regional impacts and hemispheric monsoon interactions require systematic evaluation.Addressing these gaps necessitates enhanced observational networks,refined climate models,and interdisciplinary efforts to disentangle multiscale drivers,ultimately improving resilience strategies for monsoon-dependent regions.
基金supported by National Key Research and Development Program of China(Grants No.2022YFF0802401 and 2023YFF0806900)China Postdoctoral Science Foundation(Grants No.2023M743456,GZB20230740,and 2024T170908).
文摘1.Introduction In recent years,intensifying climate extremes have triggered a sharp increase in global natural disasters,over 90%attributable to water-related hazards,particularly floods(Hirabayashi et al.,2013).Over the past two decades,floods have inundated approximately 2.23 million km2 of land worldwide(Tellman et al.,2021),affecting over 250 million people and causing economic losses exceeding USD 651 billion(Devitt et al.,2023).Recent catastrophic floods in Pakistan,landslides in Indonesia,and dike breaches in China have intensified concerns over the effectiveness of current flood management strategies.
基金Supported by the National Defense Basic Scientific Research Program of China.
文摘Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instability,occur frequently in both experimental and operational data.This infrequency causes events to be overlooked by existing prediction models,which lack the precision to accurately predict inclination attitudes in amphibious vehicles.To address this gap in predicting attitudes near extreme inclination points,this study introduces a novel loss function,termed generalized extreme value loss.Subsequently,a deep learning model for improved waterborne attitude prediction,termed iInformer,was developed using a Transformer-based approach.During the embedding phase,a text prototype is created based on the vehicle’s operation log data is constructed to help the model better understand the vehicle’s operating environment.Data segmentation techniques are used to highlight local data variation features.Furthermore,to mitigate issues related to poor convergence and slow training speeds caused by the extreme value loss function,a teacher forcing mechanism is integrated into the model,enhancing its convergence capabilities.Experimental results validate the effectiveness of the proposed method,demonstrating its ability to handle data imbalance challenges.Specifically,the model achieves over a 60%improvement in root mean square error under extreme value conditions,with significant improvements observed across additional metrics.
基金supported by the National Natural Science Foundation of China(42088101).
文摘An unprecedented extreme gale and dust event struck East Asia during 10-14 April2025.A record-breaking gale swept across most regions of China.It carried large amounts of dust from northern deserts,resulting in nationwide dust weather.Gales affected more than 3.5 million km^(2),and the windspeeds in North China were the strongest in April since 1940(Fig.1a,b).
基金supported by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science(JSPS KAKENHI)[Grant numbers JP22H02294 to M.M.,JP22K05365 and JP23K18058 to S.K.]by the commissioned research fund provided by F-REI(JPFR25020105)to S.K。
文摘Unlike animals, plants cannot move away from unfavorable environments. Instead, they must continuously adjust their growth to external conditions. When the environment is favorable, plants sustain vigorous growth. Conversely, when challenged by drought, salinity, temperature extremes, or other stresses, they must rapidly suppress growth to conserve energy and minimize damage. This capacity to switch growth on or off in response to external cues represents one of the most successful adaptive strategies that enables plants to thrive worldwide. A central mediator of this growth suppression is the phytohormone abscisic acid(ABA). Abscisic acid plays pivotal roles in stomata closure, germination inhibition, and root development modulation, thereby orchestrating defense responses under abiotic stresses(e.g., Chen et al., 2020, for a review). For this reason, ABA is often referred to as the“stress hormone” of plants. However,growth arrest is only half of the story. Once environmental conditions improve, plants must promptly resume growth to recover and compete effectively. For survival, the decision of whether“to grow or not to grow” is critical, and yet, the molecular mechanisms that enable plants to toggle this switch have long remained elusive.
基金supported by the Science and Technology Project of Sichuan Electric Power Company“Power Supply Guarantee Strategy for Urban Distribution Networks Considering Coordination with Virtual Power Plant during Extreme Weather Event”(No.521920230003).
文摘Ensuring reliable power supply in urban distribution networks is a complex and critical task.To address the increased demand during extreme scenarios,this paper proposes an optimal dispatch strategy that considers the coordination with virtual power plants(VPPs).The proposed strategy improves systemflexibility and responsiveness by optimizing the power adjustment of flexible resources.In the proposed strategy,theGaussian Process Regression(GPR)is firstly employed to determine the adjustable range of aggregated power within the VPP,facilitating an assessment of its potential contribution to power supply support.Then,an optimal dispatch model based on a leader-follower game is developed to maximize the benefits of the VPP and flexible resources while guaranteeing the power balance at the same time.To solve the proposed optimal dispatch model efficiently,the constraints of the problem are reformulated and resolved using the Karush-Kuhn-Tucker(KKT)optimality conditions and linear programming duality theorem.The effectiveness of the strategy is illustrated through a detailed case study.
基金supported by the National Natural Science Foundation of China (Grant Nos.U23A6018,42362034)the Applied Basic Research Foundation of Yunnan Province,China (Grant No.202401AS070068)。
文摘The construction of lunar bases represents a crucial goal for long-term human residence on the Moon and future deep-space exploration. Vacuum sintering of lunar regolith for in-situ resource utilization(ISRU) is considered one of the most feasible strategies for early lunar infrastructure development. However, the extreme temperature fluctuations on the lunar surface pose potential threats to the structural stability of sintered regolith materials. To investigate the mechanical deterioration and damage mechanism of vacuum-sintered lunar regolith under extreme cryogenic-thermal cycling, lunar regolith simulants are used to fabricate specimens through vacuum sintering. A series of cryogenic-thermal cycling tests is designed, combined with uniaxial compression and X-ray CT scanning, to systematically analyze their macro-micro responses. The results show that with increasing extreme cryogenic-thermal cycles, the stress-strain curves evolve from typical brittle failure to quasiductile behavior, with uniaxial compressive strength and elastic modulus decreasing by approximately 33.86% and 61.98%, respectively. CT analyses reveal that the pore structure transforms from isolated pores to connected networks, with the pore volume fraction increasing from 13.33% to 22.64%, and the fractal dimension increases from 2.465 to 2.544, and stabilizes after multiple cycles. A significant negative correlation(R^(2)> 0.96) exists between pore structural complexity and mechanical performance. Based on these findings, a thermal fatigue damage mechanism dominated by thermal stress concentration due to mismatched thermal expansion coefficients among mineral phases is proposed. This study provides scientific insights for the design, durability evaluation, and ISRU-based construction of lunar surface infrastructure.
基金supported by the National Natural Science Foundation of China (Grant No.52405033)。
文摘As unmanned underwater vehicles (UUVs) are increasingly designed to perform long-duration missions in highly complex and often extreme environments, traditional design methods face significant and growing challenges^([1,2]).
基金supported by the Key-Area Research and Development Program of Guangdong Province(No.2020B1111360003)the National Natural Science Foundation of China(Nos.42465008 and 42105164)+2 种基金Yunnan Science and Technology Department Project(No.202501AT070239)Yunnan Science and Technology Department Youth Project(No.202401AU070202)Xianyang Rapid Response Decision Support Project for Ozone(No.YZ2024-ZB019).
文摘To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) pollution control strategies.However,currently widely-used methods,such as statistical models and numerical models,exhibit inherent limitations in identifying OPS in a timely and accurate manner.In this study,we developed a novel approach to identify OPS based on eXtreme Gradient Boosting model,Shapley additive explanation(SHAP)al-gorithm,and volatile organic compound(VOC)photochemical decay adjustment,using the meteorology and speciated pollutant monitoring data as the input.By comparing the difference in SHAP values between base sce-nario and precursor reduction scenario for nitrogen oxides(NO_(x))and VOCs,OPS was divided into NO_(x)-limited,VOCs-limited and transition regime.Using the long-lasting O_(3) pollution episode in the autumn of 2022 at the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)as an example,we demonstrated large spatiotemporal heterogeneities of OPS over the GBA,which were generally shifted from NO_(x)-limited to VOCs-limited from September to October and more inclined to be VOCs-limited at the central and NO_(x)-limited in the peripheral areas.This study developed an innovative OPS identification method by comparing the difference in SHAP value before and after precursor emission reduction.Our method enables the accurate identification of OPS in the time scale of seconds,thereby providing a state-of-the-art tool for the rapid guidance of spatial-specific O_(3) control strategies.
基金supported by the National Key Research and Development Program of China(No.2022YFA1603401)National Natural Science Foundation of China(Nos.12035010 and 12342501)+1 种基金Beijing Outstanding Young Scientist Program(No.JWZQ20240101006)the Tsinghua University Dushi Program.
文摘In this study,three specific scenarios of a novel accelerator light source mechanism called steady-state microbunching(SSMB)were studied:longitudinal weak focusing,longitudinal strong focusing,and generalized longitudinal strong focusing(GLSF).At present,GLSF is the most promising method for realizing high-power short-wavelength coherent radiation with mild requirements on modulation laser power.Its essence is to exploit the ultrasmall natural vertical emittance of an electron beam in a planar storage ring for efficient microbunching formation,like a partial transverse-longitudinal emittance exchange in the optical laser wavelength range.Based on an in-depth investigation of related beam physics,a solution for a GLSF SSMB storage ring that can deliver 1 kW average-power EUV light is presented.The work in this paper,such as the generalized Courant–Snyder formalism,analysis of theoretical minimum emittances,transverse-longitudinal coupling dynamics,and derivation of the bunching factor and modulation strengths for laser-induced microbunching schemes,is expected to be useful not only for the development of SSMB but also for future accelerator light sources in general that demand increasingly precise electron beam phase space manipulations.
基金the financial support provided by the PolyU Postdoc Matching Fund 1-W34P,ITF project ITP/023/22TP,PolyU RCRE fund 1-BBCB,IWEAR fund 1-CD8E,MTR Research Funding Scheme(PTU24019)the Hong Kong Polytechnic University(P0043508 and P0044761)。
文摘NH_(4)V_(4)O_(10)(NVO)is considered a promising cathode material for aqueous zinc-ion batteries due to its high theoretical capacity.However,its practical application is limited by irreversible deamination,structural collapse,and sluggish reaction kinetics during cycling.Herein,K+and C_(3)N_(4)co-intercalated NVO(KNVO-C_(3)N_(4))nanosheets with expanded interlayer spacing are synthesized for the first time to achieve high-rate,stable,and wide-temperature cathodes.Molecular dynamics and experimental results confirm that there is an optimal C_(3)N_(4)content to achieve higher reaction kinetics.The synergistic effect of K^(+)and C_(3)N_(4)co-intercalation significantly reduces the electrostatic interaction between Zn^(2+)and the[VOn]layer,improves the specific capacity and cycling stability.Consequently,the KNVO-C_(3)N_(4)electrode displays outstanding electrochemical performance at room temperature and under extreme environments.It exhibits excellent rate performance(228.4 m Ah g^(-1)at 20 A g^(-1)),long-term cycling stability(174.2 m Ah g^(-1) after 10,000 cycles at 20 A g^(-1)),and power/energy density(210.0 Wh kg^(-1)at 14,200 W kg^(-1))at room temperature.Notably,it shows remarkable storage performance at-20℃(111.3 m Ah g^(-1)at 20 A g^(-1))and 60℃(208.6 m Ah g^(-1)at 20 A g^(-1)).This strategy offers a novel approach to developing high-performance cathodes capable of operating under extreme temperatures.
