Many machine learning-based Android malware detection often suffers from concept drift,where models trained on historical data fail to generalize to evolving threats.This paper proposes SCAN(Structural Clustering with...Many machine learning-based Android malware detection often suffers from concept drift,where models trained on historical data fail to generalize to evolving threats.This paper proposes SCAN(Structural Clustering with Adaptive thresholds for iNtelligent Android malware detection),a hybrid intelligent framework designed to mitigate concept drift without retraining.SCAN integrates Gaussian Mixture Models(GMMs)-based clustering with cluster-wise adaptive thresholding and supervised classifiers tailored to each cluster.A key challenge in clusteringbased malware detection is cluster-wise class imbalance,where clusters contain disproportionate distributions of benign and malicious samples.SCAN addresses this issue through adaptive thresholding,which dynamically adjusts the decision boundary of each cluster according to its malicious-to-benign ratio.In the final training stage,four supervised learning algorithms—Random Forest(RF),Support Vector Machine(SVM),k-NN,and XGBoost—are applied within the GMM-defined clusters.We train SCAN on Android applications collected from 2014-2017 and test it with applications from 2018-2023.Experimental results demonstrate that SCAN combined with RF consistently achieves superior performance,with both average accuracy and average F1-score exceeding 91%.These findings confirm SCAN’s robustness to concept drift and highlight its potential as a sustainable and intelligent solution for long-term Android malware detection in the real world.展开更多
Objective: To study the relationship between cortical auditory evoked potential (CAEP) thresholds and behavioral thresholds in pediatric populations with sensorineural hearing loss (SNHL). Methods: Fifteen children (m...Objective: To study the relationship between cortical auditory evoked potential (CAEP) thresholds and behavioral thresholds in pediatric populations with sensorineural hearing loss (SNHL). Methods: Fifteen children (mean age 6.8 years) with bilateral SNHL underwent behavioral pure-tone audiometry and CAEP testing at 0.5, 1, 2, and 4 kHz. CAEP thresholds were determined using tone bursts, and correlations between CAEP and pure-tone thresholds were analyzed using Pearson correlation and t-tests. Results: A strong positive correlation was observed between P1 thresholds and behavioral thresholds across all test frequencies: 0.5 kHz (r = 0.765, p Conclusion: The strong correlation between P1 and behavioral thresholds demonstrates the reliability of CAEP testing for estimating auditory thresholds in children. These findings support the use of CAEP testing as a reliable objective tool for threshold estimation, particularly in cases where behavioral responses cannot be reliably obtained. When adjusted with frequency-specific correction values, CAEP testing provides a reliable method for assessing hearing thresholds in pediatric populations.展开更多
The societal risk related to rainfalltriggered rapid debris flows is commonly managed in urbanized areas by means of early warning systems based on monitoring of hydrological parameters(such as rainfall or soil moistu...The societal risk related to rainfalltriggered rapid debris flows is commonly managed in urbanized areas by means of early warning systems based on monitoring of hydrological parameters(such as rainfall or soil moisture) and thresholds values.In Alpine catchments,this type of landslides is recurrent and represent one of the major geohazards.Debris flows are typically initiated by high-intensity rainstorms,prolonged rainfall with moderate intensity or snow melting.They frequently happen in situations of temporary infiltration into soils that are initially unsaturated.During significant rainfall events,the rise in pore water pressure can become crucial for the stability of slopes in particular areas.This phenomenon relies on hydraulic and geotechnical characteristics,along with the thickness of the involved soils.This procedure can result in a local drop in shear strength,as both apparent cohesion and effective stress decline,while driving forces rise because of the increase in unit weight.Accordingly,this study estimates Intensity-Duration(I-D) rainfall thresholds at the site-specific and distributed scales by combining empirical and physics-based approaches and modeling of soil coverings involved in soil slips or debris slides inducing debris flows.The approach was tested for mountain slopes of the Valtellina valley(Lombardia region,northern Italy),which suffered several catastrophic landslide events in the last decades.The empirical approach was adopted to reconstruct physics-based slope models of representative source areas of past debris flows events.To such a scope,nonpunctual but distributed data of hydro-mechanical soil properties and thicknesses were considered.Thus,to reconstruct the unsaturated/saturated critical conditions leading the slope instability,a combined hydrological modeling and infinite-slope stability analysis was adopted.This combined hydromechanical numerical model was used to attempt to determine a three-dimensional Intensity-Duration threshold for landslide initiation considering plausible rainfall for the Valtellina valley.Due to the lack of reliable records of past landslide hindering a thorough empirical analysis,the presented approach can be considered as a feasible approach for establishing a warning standard in urbanized areas at risk of shallow landslides triggered by rainfall.Moreover,findings highlight the importance of having access to spatially distributed soil characteristics to define and enhance input data for physics-based modelling.Finally,the proposed approach can aid an early warning system for the onset of shallow landslides by utilizing real-time rainfall monitoring or now-casting through a meteorological radar technique.展开更多
BackgroundIt's crucial to study the effect of changes in thresholds(T)and most comfortable levels(M)on behavioral measurements in young children using cochlear implants.This would help the clinician with the optim...BackgroundIt's crucial to study the effect of changes in thresholds(T)and most comfortable levels(M)on behavioral measurements in young children using cochlear implants.This would help the clinician with the optimization and validation of programming parameters.ObjectiveThe study has attempted to describe the changes in behavioral responses with modification of T and M levels.MethodsTwenty-five participants in the age range 5 to 12 years using HR90K/HiFocus1J or HR90KAdvantage/HiFocus1J with Harmony speech processors participated in the study.A decrease in T levels,a rise in T levels,or a decrease in M levels in the everyday program were used to create experimental programs.Sound field thresholds and speech perception were measured at 50 dBHL for three experimental and everyday programs.ConclusionThe results indicated that only reductions of M levels resulted in significantly(p<0.01)poor aided thresholds and speech perception.On the other hand,variation in T levels did not have significant changes in either sound field thresholds or speech perception.The results highlight that M levels must be correctly established in order to prevent decreased speech perception and audibility.展开更多
The oilseed crop Camelina sativa exhibits salinity tolerance,but the effects on early growth stages across a range of different salts and in combination with salicylic acid(SA)have not been thoroughly evaluated.In thi...The oilseed crop Camelina sativa exhibits salinity tolerance,but the effects on early growth stages across a range of different salts and in combination with salicylic acid(SA)have not been thoroughly evaluated.In this study,seeds were germinated in varying concentrations of six salts(NaCl,CaCl_(2),ZnCl_(2),KCl,MgSO_(4),and Na2SO_(4))with or without 0.5 mM SA.Using the halotime model,we estimated salt thresholds for germination and parameters of seedling growth.Germination and seedling growth parameters of camelina significantly decreased with increasing salt concentration across all salt types.Salts containing Zn and SO_(4) were most detrimental to germination and seedling growth.Except for KCl,0.5 mM SA generally reduced the salinity tolerance threshold(Saltb(50))of camelina.Specifically,Saltb(50)was 21.5%higher for KCl and 16.1%,25.0%,54.9%,21.0%,and 5.6%lower for CaCl_(2),NaCl,MgSO_(4),Na2SO_(4),and ZnCl_(2),respectively,when 0.5 mM SA was compared to 0 mM SA.Furthermore,camelina seedling growth was consistently more sensitive than germination across all salt types.SA did not significantly enhance germination or seedling growth and was harmful when combined with certain salts or at the germination stage.It can be concluded that both the type of salt and the concentration of SA are as critical as the salt concentration in saline irrigation water.展开更多
The geostress and rock blasting in underground engineering may greatly affect the stress thresholds of surrounding rock.In this study,pre-damage impact tests were first conducted on granite under varying confining pre...The geostress and rock blasting in underground engineering may greatly affect the stress thresholds of surrounding rock.In this study,pre-damage impact tests were first conducted on granite under varying confining pressures(5,10 and 15 MPa)and numbers of impacts(1,5,10 and 15 impacts).Then,uniaxial compression tests were undertaken on the pre-damaged granite to study the evolution of stress thresholds using the crack volume strain method and acoustic emission method.The crack damage stresses determined by the two methods were compared.Additionally,based on the rise time amplitude and average frequency,the evolution law of microcracks inside rock specimens was revealed,and an improved acoustic emission method was proposed.The results indicated that as the number of impacts increased,the crack closure stress,crack damage stress,and peak stress of granite specimens initially rose and then declined,while they continuously increased with the confining pressure.The proportion of shear cracks first declined and then rose with greater number of impacts and decreased with higher confining pressure,and that of tensile cracks showed the opposite trend.The improved acoustic emission method was more accurate in identifying the crack damage stress.展开更多
We investigate the mixed-state entanglement between two spins embedded in the XXZ Heisenberg chain under thermal equilibrium.By deriving an analytical expression for the entanglement of two-spin thermal states and ext...We investigate the mixed-state entanglement between two spins embedded in the XXZ Heisenberg chain under thermal equilibrium.By deriving an analytical expression for the entanglement of two-spin thermal states and extending this analysis to larger spin chains,we demonstrate that mixed-state entanglement is profoundly shaped by both disorder and temperature.Our results reveal a sharp distinction between many-body localized and ergodic phases,with entanglement vanishing above diferent fnite temperature thresholds.Furthermore,by analyzing non-adjacent spins,we uncover an approximate exponential decay of entanglement with separation.This work advances the understanding of the quantum-to-classical transition by linking the entanglement properties of small subsystems to the broader thermal environment,ofering an explanation for the absence of entanglement in macroscopic systems.These fndings provide critical insights into quantum many-body physics,bridging concepts from thermalization,localization,and quantum information theory.展开更多
Urban spatial morphology(USM)optimization is critical to balancing biodiversity conservation and sustainable urbanization.However,previous studies predominantly focused on the socio-economic efficiency and static ecol...Urban spatial morphology(USM)optimization is critical to balancing biodiversity conservation and sustainable urbanization.However,previous studies predominantly focused on the socio-economic efficiency and static ecological metrics and rarely addressed the dynamic USM optimization across spatial scales.Here,we developed a multi-level ecological network(MEN)framework to resolve the tension between urban expansion and ecological integrity.By integrating the cost-weighted distance analysis with a hierarchical network transmission mechanism,we established a cross-scale spatial optimization system,which coordinated the regional ecological corridors and local habitat patches.Comparative experiments with conventional single-scale approaches and scenario simulations using the PLUS model show that the MEN framework had superior performance in three dimensions:(1)spatial governance:the primary-level network(peri-urban natural reserves)effectively contained urban sprawl,and the secondary-level network(intra-urban green corridors)mitigated habitat fragmentation and improved the built-environment;(2)scenario robustness:the model maintained an optimal compactness-loose balance in multiple development pathways;(3)landscape metrics:patch fragmentation decreased by 18.25%,and the internal landscape richness improved by 10.66%compared to the scenario without USM optimization.The findings provide new insight to establish a hierarchical ecological optimization framework as a nature-based spatial protocol to reconcile metropolitan growth with landscape sustainability.展开更多
Amid accelerating global land degradation,establishing high-efficiency ecological restoration principles and frameworks is crucial.Here,we explore the application of threshold effects in the ecological restoration pro...Amid accelerating global land degradation,establishing high-efficiency ecological restoration principles and frameworks is crucial.Here,we explore the application of threshold effects in the ecological restoration process based on field experiments and globally available experimental data from 173 sites.Combining data integration analysis and meta-analysis,we collectively verified the universality of threshold effects in grasslands.The global grasslands’average nitrogen application threshold is 3.78 g·m^(-2)·yr^(−1),while the threshold value of degraded grassland(3.65 g·m^(-2)·yr^(−1))is lower than that of nondegraded grassland(5.90 g·m^(-2)·yr^(−1)).The low nitrogen-driven thresholds are affected by degradation status,climate(precipitation and temperature),and other site conditions,but not fertilization forms.Independent experiments further demonstrated that an increase in soil moisture content can lead to the disappearance of nitrogen threshold effects,revealing that ecological threshold effects are influenced by ecosystem stress factors.Following the significant increase in plant biomass triggered by the nitrogen threshold,the ecosystem undergoes systemic improvement.Soil organic carbon,urease activity,soil microbial diversity,and other soil properties are significantly enhanced.Soil nitrogen cycle-related microbial communities and soil physicochemical attributes are significantly activated.The results indicate that a threshold response pattern may develop before nitrogen saturation is reached,and low nitrogen input can boost productivity and improve the plant-soil-microbe system.Our findings reveal a nonprogressive path of restoration in degraded ecosystems,and thus,restoration based on threshold effects can offer an efficient and safe solution to combat ecological degradation.展开更多
An optimization model has been established and solved to determine the optimal threshold value for the event-triggered self-adaptive optimization strategy,which aims to strike a balance between optimization performanc...An optimization model has been established and solved to determine the optimal threshold value for the event-triggered self-adaptive optimization strategy,which aims to strike a balance between optimization performance and control load while ensuring continuous optimization.First,evaluation indicators are introduced to comprehensively analyze the impact of power fluctuations on the objective function and system voltage at both the system-wide and local levels.Based on these indicators,a multi-stage centralized optimization(MCO)is selectively applied,addressing system state deviations to achieve optimal operating states while maintaining a voltage security margin to ensure system safety.Then,distributed optimization(DO)is carried out at each bus with a renewable energy source or random load integration to accommodate short-term uncertainties using a self-adaptive reactive power algorithm.The optimal threshold value for event-triggered DO is calculated to balance control burden and optimization effectiveness.Utilizing the local state deviation evaluation indicator,unnecessary DOs are skipped when minor power fluctuations occur at the local level.Finally,following the linear superposition principle,event-triggered DOs executed at all distributed controllers collectively constitute the self-adaptive optimization strategy for the entire system.A case study on the IEEE New England 39-bus power system illustrates the effectiveness of the proposed strategy.展开更多
The influence of different solution and aging conditions on the microstructure,impact toughness,and crack initiation and propagation mechanisms of the novel α+β titanium alloy Ti6422 was systematically investigated....The influence of different solution and aging conditions on the microstructure,impact toughness,and crack initiation and propagation mechanisms of the novel α+β titanium alloy Ti6422 was systematically investigated.By adjusting the furnace cooling time after solution treatment and the aging temperature,Ti6422 alloy samples were developed with a multi-level lamellar microstructure,in-cluding microscaleαcolonies and α_(p) lamellae,as well as nanoscale α_(s) phases.Extending the furnace cooling time after solution treatment at 920℃ for 1 h from 240 to 540 min,followed by aging at 600℃ for 6 h,increased the α_(p) lamella content,reduced the α_(s) phase content,expanded theαcolonies and α_(p) lamellae size,and improved the impact toughness from 22.7 to 53.8 J/cm^(2).Additionally,under the same solution treatment,raising the aging temperature from 500 to 700℃ resulted in a decrease in the α_(s) phase content and a growth in the thickness of the α_(p) lamella and α_(s) phase.The impact toughness increased significantly with these changes.Samples with high α_(p) lamellae content or large α_(s) phase size exhibited high crack initiation and propagation energies.Impact deformation caused severe kinking of the α_(p) lamellae in crack initiation and propagation areas,leading to a uniform and high-density kernel average misorientation(KAM)distribu-tion,enhancing plastic deformation coordination and uniformity.Moreover,the multidirectional arrangement of coarserαcolonies and α_(p) lamellae continuously deflect the crack propagation direction,inhibiting crack propagation.展开更多
Understanding Cd contamination in the soil-rice ecosystem and the underlying its threshold and interaction effects is crucial for controlling Cd pollution and ensuring food safety.Although the quantitative relationshi...Understanding Cd contamination in the soil-rice ecosystem and the underlying its threshold and interaction effects is crucial for controlling Cd pollution and ensuring food safety.Although the quantitative relationships between Cd and environmental variables have been extensively studied,the threshold and interaction effects of multi-source environmental variables remain largely unexplored.This study employs a combination of random forest analysis and a human health risk model to investigate the effects of variables on Cd levels in rice grains,with the goal of quantifying their contributions and elucidating their relationships.The results indicated that the 15 selected variables collectively explained 47.36%of the variation in Cd content,with the top three variables being soil pH,distance from industrial park,and soil Zn.The majority of variables exhibited threshold effects on Cd levels in rice grains.By visualizing the interaction between Soil pH,distance from industrial park,and soil Zn with Cd levels in rice,we demonstrate the threshold effects of them on Cd level in rice grains,thereby providing further insight into the variation observed.Furthermore,oral intake of rice has been identified as the primary route of human exposure,significantly contributing to overall exposure pathways.Understanding these interactions is crucial for gaining insights into the underlying processes driving Cd pollution and fostering sustainable development within the industry.Our findings underscore the crucial need to consider multiple environmental variables and their interactions when managing heavy metals(HMs)contamination and mitigating health risks.展开更多
Multilevel image segmentation is a critical task in image analysis,which imposes high requirements on the global search capability and convergence efficiency of segmentation algorithms.In this paper,an improved Artifi...Multilevel image segmentation is a critical task in image analysis,which imposes high requirements on the global search capability and convergence efficiency of segmentation algorithms.In this paper,an improved Artificial Protozoa Optimization algorithm,termed the two-stage Taguchi-assisted Gaussian–Levy Artificial Protozoa Optimization(TGAPO)algorithm,is proposed and applied tomultilevel image segmentation.The proposed algorithm adopts a two-stage evolutionary mechanism.In the first stage,Gaussian perturbation is introduced to enhance local search capability;in the second stage,Levy flight is incorporated to expand the global search range;and finally,the Taguchi strategy is employed to further refine the optimal solution.Consequently,the global optimization performance and robustness of the algorithm are significantly improved.To evaluate the effectiveness of the proposed TGAPO algorithm,comparative experiments are conducted with representative optimization algorithms,including the Grey Wolf Optimizer(GWO)and Particle Swarm Optimization(PSO),in the context ofmultilevel image segmentation.The segmentation quality is assessed using the minimum cross-entropy function as the performance metric.Experimental results demonstrate that the TGAPO algorithm outperforms the comparison algorithms in terms of segmentation accuracy and convergence speed,and exhibits superior stability in high-threshold segmentation tasks.Furthermore,the proposedmethod achieves excellentmulti-threshold segmentation performance for color images and shows strong potential for practical applications.展开更多
Sleep is a biological phenomenon with highly conserved evolutionary characteristics.The American Academy of Sleep Medicine and the Sleep Research Society recommend that adults get at least 7 hours of sleep per night[1...Sleep is a biological phenomenon with highly conserved evolutionary characteristics.The American Academy of Sleep Medicine and the Sleep Research Society recommend that adults get at least 7 hours of sleep per night[1].However,the stress caused by fast-paced life often leads to sleep deprivation(SD).SD is strongly associated with damage to the auditory system[2,3].Obstructive sleep apnea-hypopnea syndrome(OSAHS)is a common sleep disorder.Clinical observations indicate that some patients with OSAHS experience persistent hearing loss accompanied by tinnitus and other symptoms[4].More than 61.8%of patients with sudden deafness experienced SD[5].展开更多
To investigate the eco-economic thresholds of weeds and the critical period for their control,combining economic and ecological perspectives to achieve scientific weed management,four dominant weeds,Echinochloa crus-g...To investigate the eco-economic thresholds of weeds and the critical period for their control,combining economic and ecological perspectives to achieve scientific weed management,four dominant weeds,Echinochloa crus-galli(L.)P.Beauv,Chenopodium album L.,Digitaria sanguinalis(L.)Scop,and Commelina communis L.,were selected as experimental subjects,based on their common occurrence in spring maize planting areas in Northern China.A predictive model for maize yield loss caused by mixed weed populations was established.The study analyzed the eco-economic thresholds of weeds under different control measures and determined the optimal period for weed control by combining the critical control period.A logarithmic function model was developed to describe the relationship between mixed weed density and maize yield loss:y=5.9875ln(x)-6.5407(R^(2)=0.949,F=131.244,P=0.000).The optimal model for the critical period of competition between weeds and maize in maize fields was:y=-0.0027x^(2)+0.5624x-10.064(R2=0.968,F=30.513,P=0.032).When the weed density in maize fields reached 5.57 plants·m^(-2),manual weeding should be conducted promptly.When the weed density was 3.41 plants·m^(-2) or 3.48 plants·m^(-2),soil or foliar treatments should be applied,respectively.If the weed density reached 3.93 plants·m^(-2),a combination of soil and foliar treatment should be implemented.The critical period for manual weeding was 28.4 days after sowing,for soil treatment it was 19.9 days,for foliar treatment it was 21.8 days,and for the combined treatment of soil and foliar methods,it was 23.5 days after sowing.Retaining weeds for up to 15 days after maize sowing did not result in a yield loss and could even have a positive effect on maize yield.展开更多
Objective To investigate changes that occur in the brain when the physiological convulsive threshold becomes pathological,and to determine what differences occur in pathological and physiological convulsive thresholds...Objective To investigate changes that occur in the brain when the physiological convulsive threshold becomes pathological,and to determine what differences occur in pathological and physiological convulsive thresholds during the development of epilepsy. Methods In this study,the threshold for convulsions was determined by direct cortical stimulation in rats.The convulsive threshold was measured while recording electroencephalograms and subsequently examining histopathological changes in the hippocampus. Results At the beginning of the experiment,convulsive thresholds were all above 1 100 μA although there were significant individual variations in rats of the same group.But those thresholds quickly declined during the initial 4 weeks of repetitive electrical stimulation.The convulsive thresholds approached a constant level[TLS(430±34)μA,TGS(480±46)μA,TPS(605±70)μA]in the 10th week.There were no significant changes in thresholds when stimulation lasted for longer,the convulsive thresholds and the variations in rats of the same group were significantly lower than that at the beginning of the trial(P<0.01).An interictal discharge was also recorded in the 3rd week in heavy current group and at the 8th week in weak current group respectively which were concomitant with the neuronal da-mage and loss in the hippocampus.There was no abnormality observed in control group. Conclusion These findings indicate that the convulsion threshold in the brain should be divided into two stages:physiological convulsive threshold and pathological convulsive threshold(epileptic threshold).Epileptic threshold is created by pathological acquired factors which give rise to brain damage.The intensity of these pathological acquired factors is correlated with the formation of the pathological convulsive threshold.展开更多
It is imperative to derive an appropriate cadmium (Cd) health risk toxicity threshold for paddy soils to ensure the Cd con-centration of rice grains meet the food safety standard. In this study, 20 rice cultivars from...It is imperative to derive an appropriate cadmium (Cd) health risk toxicity threshold for paddy soils to ensure the Cd con-centration of rice grains meet the food safety standard. In this study, 20 rice cultivars from the main rice producing areas in China were selected, and a pot-experiment was conducted to investigate transformation of Cd in paddy soil-rice system with 0 (CK), 0.3 mg kg–1 (T1) and 0.6 mg kg–1 (T2) Cd treatments in greenhouse. The results showed that Cd concentrations of rice grains existed signiifcant difference (P<0.05) in 20 rice cultivars under the same Cd level in soil. The Cd concentrations of rice grains of the CK, T1 and T2 treatments were in the range of 0.143–0.202, 0.128–0.458 and 0.332–0.806 mg kg–1, respectively. Marked differences of the ratios of Cd concentration for soil to rice grain (BCFs) and transfer factors (TFs, root to grain and straw to grain) among the tested cultivars were observed in this study. The bioconcentration factors (BCFgrain) and TFs of the 20 rice cultivars were 0.300–1.112 and 0.342–0.817, respectively. The TFs of Cd from straw to grain ranged from 0.366 to 1.71, with signiifcant differences among these 20 rice cultivars. The bioconcentration factors (BCFgrain) and TFs among the 20 rice cultivars ranged from 0.300–1.112 and 0.342–0.817, respectively. The species-sensitivity distribu-tion (SSD) of Cd sensitivity of the rice species could be iftted wel with Burr-III (R2=0.987) based on the data of BCFs. The toxicity threshold of Cd derived from SSD for the paddy soil was 0.507 mg kg–1 in the present study.展开更多
The hand-held soil plant analysis development （SPAD） chlorophyll meter nitrogen status of the potato and guiding fertilization recommendations N recommendation, it is critical to establish the threshold SPAD value h...The hand-held soil plant analysis development （SPAD） chlorophyll meter nitrogen status of the potato and guiding fertilization recommendations N recommendation, it is critical to establish the threshold SPAD value has proved to be a promising tool in evaluating the n the process of N evaluation of potato plants and （SPAD reading）, below which nitrogen supplement is required. And taking convenient using into account, the threshold needs to be dynamic throughout the potato growing season so that the users can test their potato plants and make fertilization decision at any growing time of potato. To complete this goal, field experiments with different nitrogen supply levels were conducted in different sites in northern China from 2009 to 2011. The results showed that threshold SPAD values decrease as the growing season progresses for all cultivars and planting sites. By statistical analysis, the threshold regression models were established respectively as： y=-0.003χ2-0.0507χ＋58.213 （y, threshold SPAD value; χ, days after emergence） for the potato cultivar Kexin 1, and y=-0.003χ2＋0.017χ＋52.489 （y, threshold SPAD value; χ, days after emergence） for the cultivar Shepody, from which, the threshold SPAD value at any day after emergence can be calculated.展开更多
The influences of biological,chemical,and flow processes on soil structure through microbially induced carbonate precipitation(MICP)are not yet fully understood.In this study,we use a multi-level thresholding segmenta...The influences of biological,chemical,and flow processes on soil structure through microbially induced carbonate precipitation(MICP)are not yet fully understood.In this study,we use a multi-level thresholding segmentation algorithm,genetic algorithm(GA)enhanced Kapur entropy(KE)(GAE-KE),to accomplish quantitative characterization of sandy soil structure altered by MICP cementation.A sandy soil sample was treated using MICP method and scanned by the synchrotron radiation(SR)micro-CT with a resolution of 6.5 mm.After validation,tri-level thresholding segmentation using GAE-KE successfully separated the precipitated calcium carbonate crystals from sand particles and pores.The spatial distributions of porosity,pore structure parameters,and flow characteristics were calculated for quantitative characterization.The results offer pore-scale insights into the MICP treatment effect,and the quantitative understanding confirms the feasibility of the GAE-KE multi-level thresholding segmentation algorithm.展开更多
Penile hypersensitivity plays an important role in premature ejaculation （PE）, but differences in penile sensitivity among subtypes of PE are unknown. Therefore, we compared penile sensory thresholds in PE subtypes ...Penile hypersensitivity plays an important role in premature ejaculation （PE）, but differences in penile sensitivity among subtypes of PE are unknown. Therefore, we compared penile sensory thresholds in PE subtypes of lifelong and acquired PE, PE with and without erectile dysfunction （ED）, PE with an intravaginal ejaculation latency time 〈1 min and 〉1 min, and PE with and without orgasmic pleasure perceptual dysfunction. During August 2014 to January 2016, 136 patients with PE were included. Penile warm, cold, and vibratory thresholds were measured. Data of clinical characteristics, sexual life, Premature Ejaculation Diagnostic Tool （PEDT） score, and the 5-item version of the International Index of Erectile Function （IIEF-5） score were collected. Vibratory thresholds of the PE with ED group were higher in the right coronal sulcus （median amplitude： 4.92 vs 3.65 μm, P= 0.02） and the right penile shaft （median amplitude： 3.87 vs 3.30 μm, P = 0.03）, while differences in penile sensory thresholds between other subtypes were not significant. The median PEDT score was lower in the PE without ED group （12 vs 14, P 〈 0.001）. The IIEF-5 and PEDT scores were negatively correlated （r = -0.29, P 〈 0.001）. Patients with orgasmic pleasure perceptual dysfunction had a lower median IIEF-5 score （20 vs 21, P = 0.02）. Patients with PE and ED had lower penile sensitivity, and ED was associated with more severe symptoms and weaker orgasmic pleasure perception. In men with PE, management of comorbid ED is necessary. In case of side effects in erectile function, topical anesthetics should be cautiously used in men with PE and ED.展开更多
基金supported in part by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(No.2021R1A2C2012574)in part by the IITP(Institute of Information&Communications Technology Planning&Evaluation)-ITRC(Information Technology Research Center)grant funded by the Korea government(Ministry of Science and ICT)(IITP-2025-RS-2023-00259967).
文摘Many machine learning-based Android malware detection often suffers from concept drift,where models trained on historical data fail to generalize to evolving threats.This paper proposes SCAN(Structural Clustering with Adaptive thresholds for iNtelligent Android malware detection),a hybrid intelligent framework designed to mitigate concept drift without retraining.SCAN integrates Gaussian Mixture Models(GMMs)-based clustering with cluster-wise adaptive thresholding and supervised classifiers tailored to each cluster.A key challenge in clusteringbased malware detection is cluster-wise class imbalance,where clusters contain disproportionate distributions of benign and malicious samples.SCAN addresses this issue through adaptive thresholding,which dynamically adjusts the decision boundary of each cluster according to its malicious-to-benign ratio.In the final training stage,four supervised learning algorithms—Random Forest(RF),Support Vector Machine(SVM),k-NN,and XGBoost—are applied within the GMM-defined clusters.We train SCAN on Android applications collected from 2014-2017 and test it with applications from 2018-2023.Experimental results demonstrate that SCAN combined with RF consistently achieves superior performance,with both average accuracy and average F1-score exceeding 91%.These findings confirm SCAN’s robustness to concept drift and highlight its potential as a sustainable and intelligent solution for long-term Android malware detection in the real world.
文摘Objective: To study the relationship between cortical auditory evoked potential (CAEP) thresholds and behavioral thresholds in pediatric populations with sensorineural hearing loss (SNHL). Methods: Fifteen children (mean age 6.8 years) with bilateral SNHL underwent behavioral pure-tone audiometry and CAEP testing at 0.5, 1, 2, and 4 kHz. CAEP thresholds were determined using tone bursts, and correlations between CAEP and pure-tone thresholds were analyzed using Pearson correlation and t-tests. Results: A strong positive correlation was observed between P1 thresholds and behavioral thresholds across all test frequencies: 0.5 kHz (r = 0.765, p Conclusion: The strong correlation between P1 and behavioral thresholds demonstrates the reliability of CAEP testing for estimating auditory thresholds in children. These findings support the use of CAEP testing as a reliable objective tool for threshold estimation, particularly in cases where behavioral responses cannot be reliably obtained. When adjusted with frequency-specific correction values, CAEP testing provides a reliable method for assessing hearing thresholds in pediatric populations.
文摘The societal risk related to rainfalltriggered rapid debris flows is commonly managed in urbanized areas by means of early warning systems based on monitoring of hydrological parameters(such as rainfall or soil moisture) and thresholds values.In Alpine catchments,this type of landslides is recurrent and represent one of the major geohazards.Debris flows are typically initiated by high-intensity rainstorms,prolonged rainfall with moderate intensity or snow melting.They frequently happen in situations of temporary infiltration into soils that are initially unsaturated.During significant rainfall events,the rise in pore water pressure can become crucial for the stability of slopes in particular areas.This phenomenon relies on hydraulic and geotechnical characteristics,along with the thickness of the involved soils.This procedure can result in a local drop in shear strength,as both apparent cohesion and effective stress decline,while driving forces rise because of the increase in unit weight.Accordingly,this study estimates Intensity-Duration(I-D) rainfall thresholds at the site-specific and distributed scales by combining empirical and physics-based approaches and modeling of soil coverings involved in soil slips or debris slides inducing debris flows.The approach was tested for mountain slopes of the Valtellina valley(Lombardia region,northern Italy),which suffered several catastrophic landslide events in the last decades.The empirical approach was adopted to reconstruct physics-based slope models of representative source areas of past debris flows events.To such a scope,nonpunctual but distributed data of hydro-mechanical soil properties and thicknesses were considered.Thus,to reconstruct the unsaturated/saturated critical conditions leading the slope instability,a combined hydrological modeling and infinite-slope stability analysis was adopted.This combined hydromechanical numerical model was used to attempt to determine a three-dimensional Intensity-Duration threshold for landslide initiation considering plausible rainfall for the Valtellina valley.Due to the lack of reliable records of past landslide hindering a thorough empirical analysis,the presented approach can be considered as a feasible approach for establishing a warning standard in urbanized areas at risk of shallow landslides triggered by rainfall.Moreover,findings highlight the importance of having access to spatially distributed soil characteristics to define and enhance input data for physics-based modelling.Finally,the proposed approach can aid an early warning system for the onset of shallow landslides by utilizing real-time rainfall monitoring or now-casting through a meteorological radar technique.
文摘BackgroundIt's crucial to study the effect of changes in thresholds(T)and most comfortable levels(M)on behavioral measurements in young children using cochlear implants.This would help the clinician with the optimization and validation of programming parameters.ObjectiveThe study has attempted to describe the changes in behavioral responses with modification of T and M levels.MethodsTwenty-five participants in the age range 5 to 12 years using HR90K/HiFocus1J or HR90KAdvantage/HiFocus1J with Harmony speech processors participated in the study.A decrease in T levels,a rise in T levels,or a decrease in M levels in the everyday program were used to create experimental programs.Sound field thresholds and speech perception were measured at 50 dBHL for three experimental and everyday programs.ConclusionThe results indicated that only reductions of M levels resulted in significantly(p<0.01)poor aided thresholds and speech perception.On the other hand,variation in T levels did not have significant changes in either sound field thresholds or speech perception.The results highlight that M levels must be correctly established in order to prevent decreased speech perception and audibility.
基金the Genetics and Agricultural Biotechnology Institute of Tabarestan (GABIT) Sari Agricultural Sciences and Natural Resources University (SANRU) for the use of the services and financial supports of this research
文摘The oilseed crop Camelina sativa exhibits salinity tolerance,but the effects on early growth stages across a range of different salts and in combination with salicylic acid(SA)have not been thoroughly evaluated.In this study,seeds were germinated in varying concentrations of six salts(NaCl,CaCl_(2),ZnCl_(2),KCl,MgSO_(4),and Na2SO_(4))with or without 0.5 mM SA.Using the halotime model,we estimated salt thresholds for germination and parameters of seedling growth.Germination and seedling growth parameters of camelina significantly decreased with increasing salt concentration across all salt types.Salts containing Zn and SO_(4) were most detrimental to germination and seedling growth.Except for KCl,0.5 mM SA generally reduced the salinity tolerance threshold(Saltb(50))of camelina.Specifically,Saltb(50)was 21.5%higher for KCl and 16.1%,25.0%,54.9%,21.0%,and 5.6%lower for CaCl_(2),NaCl,MgSO_(4),Na2SO_(4),and ZnCl_(2),respectively,when 0.5 mM SA was compared to 0 mM SA.Furthermore,camelina seedling growth was consistently more sensitive than germination across all salt types.SA did not significantly enhance germination or seedling growth and was harmful when combined with certain salts or at the germination stage.It can be concluded that both the type of salt and the concentration of SA are as critical as the salt concentration in saline irrigation water.
基金Project(2023YFC2907400)by the National Key Research and Development Program of China-2023 Key Special ProjectProject(51974043)supported by the National Natural Science Foundation of China+2 种基金Project(SKLCRKF1908)supported by the Open Fund of the State Key Laboratory of Coal Resources in Western China,Xi’an University of Science and Technology,ChinaProject(2023JJ10072)suupported by the Hunan Provincial Natural Science Foundation for Distinguished Young ScholarsProject(2022RC1173)supported by the Science and Technology Innovation Program of Hunan Province,China。
文摘The geostress and rock blasting in underground engineering may greatly affect the stress thresholds of surrounding rock.In this study,pre-damage impact tests were first conducted on granite under varying confining pressures(5,10 and 15 MPa)and numbers of impacts(1,5,10 and 15 impacts).Then,uniaxial compression tests were undertaken on the pre-damaged granite to study the evolution of stress thresholds using the crack volume strain method and acoustic emission method.The crack damage stresses determined by the two methods were compared.Additionally,based on the rise time amplitude and average frequency,the evolution law of microcracks inside rock specimens was revealed,and an improved acoustic emission method was proposed.The results indicated that as the number of impacts increased,the crack closure stress,crack damage stress,and peak stress of granite specimens initially rose and then declined,while they continuously increased with the confining pressure.The proportion of shear cracks first declined and then rose with greater number of impacts and decreased with higher confining pressure,and that of tensile cracks showed the opposite trend.The improved acoustic emission method was more accurate in identifying the crack damage stress.
基金supported by the National Natural Science Foundation of China(Grant Nos.92365202,12475011,and 11921005)the National Key R&D Program of China(Grant No.2024YFA1409002)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)。
文摘We investigate the mixed-state entanglement between two spins embedded in the XXZ Heisenberg chain under thermal equilibrium.By deriving an analytical expression for the entanglement of two-spin thermal states and extending this analysis to larger spin chains,we demonstrate that mixed-state entanglement is profoundly shaped by both disorder and temperature.Our results reveal a sharp distinction between many-body localized and ergodic phases,with entanglement vanishing above diferent fnite temperature thresholds.Furthermore,by analyzing non-adjacent spins,we uncover an approximate exponential decay of entanglement with separation.This work advances the understanding of the quantum-to-classical transition by linking the entanglement properties of small subsystems to the broader thermal environment,ofering an explanation for the absence of entanglement in macroscopic systems.These fndings provide critical insights into quantum many-body physics,bridging concepts from thermalization,localization,and quantum information theory.
基金National Key Research and Development Program of China,No.2019YFD1101304National Natural Science Foundation of China,No.52278059+1 种基金Natural Science Foundation of Hunan Province of China,No.2024JJ8316Hunan Provincial Innovation Foundation For Postgraduate,No.CX20250634。
文摘Urban spatial morphology(USM)optimization is critical to balancing biodiversity conservation and sustainable urbanization.However,previous studies predominantly focused on the socio-economic efficiency and static ecological metrics and rarely addressed the dynamic USM optimization across spatial scales.Here,we developed a multi-level ecological network(MEN)framework to resolve the tension between urban expansion and ecological integrity.By integrating the cost-weighted distance analysis with a hierarchical network transmission mechanism,we established a cross-scale spatial optimization system,which coordinated the regional ecological corridors and local habitat patches.Comparative experiments with conventional single-scale approaches and scenario simulations using the PLUS model show that the MEN framework had superior performance in three dimensions:(1)spatial governance:the primary-level network(peri-urban natural reserves)effectively contained urban sprawl,and the secondary-level network(intra-urban green corridors)mitigated habitat fragmentation and improved the built-environment;(2)scenario robustness:the model maintained an optimal compactness-loose balance in multiple development pathways;(3)landscape metrics:patch fragmentation decreased by 18.25%,and the internal landscape richness improved by 10.66%compared to the scenario without USM optimization.The findings provide new insight to establish a hierarchical ecological optimization framework as a nature-based spatial protocol to reconcile metropolitan growth with landscape sustainability.
基金supported by the Major Special Projects of the National Natural Science Foundation of China(Grants No.52374170 and 42377465)the Third Comprehensive Scientific Exploration in Xinjiang(Grant No.2022xjkk1005)+1 种基金the Special Technology Innovation Fund of Carbon Peak and Carbon Neutrality in Jiangsu Province(Grant No.BK20231515)the Shaanxi Shenmu Natural Field Observation and Research Station of Erosion and Environment,which provided the site and data on experimental conditions for field trials.
文摘Amid accelerating global land degradation,establishing high-efficiency ecological restoration principles and frameworks is crucial.Here,we explore the application of threshold effects in the ecological restoration process based on field experiments and globally available experimental data from 173 sites.Combining data integration analysis and meta-analysis,we collectively verified the universality of threshold effects in grasslands.The global grasslands’average nitrogen application threshold is 3.78 g·m^(-2)·yr^(−1),while the threshold value of degraded grassland(3.65 g·m^(-2)·yr^(−1))is lower than that of nondegraded grassland(5.90 g·m^(-2)·yr^(−1)).The low nitrogen-driven thresholds are affected by degradation status,climate(precipitation and temperature),and other site conditions,but not fertilization forms.Independent experiments further demonstrated that an increase in soil moisture content can lead to the disappearance of nitrogen threshold effects,revealing that ecological threshold effects are influenced by ecosystem stress factors.Following the significant increase in plant biomass triggered by the nitrogen threshold,the ecosystem undergoes systemic improvement.Soil organic carbon,urease activity,soil microbial diversity,and other soil properties are significantly enhanced.Soil nitrogen cycle-related microbial communities and soil physicochemical attributes are significantly activated.The results indicate that a threshold response pattern may develop before nitrogen saturation is reached,and low nitrogen input can boost productivity and improve the plant-soil-microbe system.Our findings reveal a nonprogressive path of restoration in degraded ecosystems,and thus,restoration based on threshold effects can offer an efficient and safe solution to combat ecological degradation.
基金supported in part by National Key R&D Program of China(2022YFF0610600).
文摘An optimization model has been established and solved to determine the optimal threshold value for the event-triggered self-adaptive optimization strategy,which aims to strike a balance between optimization performance and control load while ensuring continuous optimization.First,evaluation indicators are introduced to comprehensively analyze the impact of power fluctuations on the objective function and system voltage at both the system-wide and local levels.Based on these indicators,a multi-stage centralized optimization(MCO)is selectively applied,addressing system state deviations to achieve optimal operating states while maintaining a voltage security margin to ensure system safety.Then,distributed optimization(DO)is carried out at each bus with a renewable energy source or random load integration to accommodate short-term uncertainties using a self-adaptive reactive power algorithm.The optimal threshold value for event-triggered DO is calculated to balance control burden and optimization effectiveness.Utilizing the local state deviation evaluation indicator,unnecessary DOs are skipped when minor power fluctuations occur at the local level.Finally,following the linear superposition principle,event-triggered DOs executed at all distributed controllers collectively constitute the self-adaptive optimization strategy for the entire system.A case study on the IEEE New England 39-bus power system illustrates the effectiveness of the proposed strategy.
基金supported by the National Natural Science Foundation of China(No.52090041).
文摘The influence of different solution and aging conditions on the microstructure,impact toughness,and crack initiation and propagation mechanisms of the novel α+β titanium alloy Ti6422 was systematically investigated.By adjusting the furnace cooling time after solution treatment and the aging temperature,Ti6422 alloy samples were developed with a multi-level lamellar microstructure,in-cluding microscaleαcolonies and α_(p) lamellae,as well as nanoscale α_(s) phases.Extending the furnace cooling time after solution treatment at 920℃ for 1 h from 240 to 540 min,followed by aging at 600℃ for 6 h,increased the α_(p) lamella content,reduced the α_(s) phase content,expanded theαcolonies and α_(p) lamellae size,and improved the impact toughness from 22.7 to 53.8 J/cm^(2).Additionally,under the same solution treatment,raising the aging temperature from 500 to 700℃ resulted in a decrease in the α_(s) phase content and a growth in the thickness of the α_(p) lamella and α_(s) phase.The impact toughness increased significantly with these changes.Samples with high α_(p) lamellae content or large α_(s) phase size exhibited high crack initiation and propagation energies.Impact deformation caused severe kinking of the α_(p) lamellae in crack initiation and propagation areas,leading to a uniform and high-density kernel average misorientation(KAM)distribu-tion,enhancing plastic deformation coordination and uniformity.Moreover,the multidirectional arrangement of coarserαcolonies and α_(p) lamellae continuously deflect the crack propagation direction,inhibiting crack propagation.
基金supported by the GDAS’Project of Science and Technology Development(No.2022GDASZH-2022010104-2)Guangdong Major Project of Basic and Applied Basic Research(No.2023B0303000006).
文摘Understanding Cd contamination in the soil-rice ecosystem and the underlying its threshold and interaction effects is crucial for controlling Cd pollution and ensuring food safety.Although the quantitative relationships between Cd and environmental variables have been extensively studied,the threshold and interaction effects of multi-source environmental variables remain largely unexplored.This study employs a combination of random forest analysis and a human health risk model to investigate the effects of variables on Cd levels in rice grains,with the goal of quantifying their contributions and elucidating their relationships.The results indicated that the 15 selected variables collectively explained 47.36%of the variation in Cd content,with the top three variables being soil pH,distance from industrial park,and soil Zn.The majority of variables exhibited threshold effects on Cd levels in rice grains.By visualizing the interaction between Soil pH,distance from industrial park,and soil Zn with Cd levels in rice,we demonstrate the threshold effects of them on Cd level in rice grains,thereby providing further insight into the variation observed.Furthermore,oral intake of rice has been identified as the primary route of human exposure,significantly contributing to overall exposure pathways.Understanding these interactions is crucial for gaining insights into the underlying processes driving Cd pollution and fostering sustainable development within the industry.Our findings underscore the crucial need to consider multiple environmental variables and their interactions when managing heavy metals(HMs)contamination and mitigating health risks.
文摘Multilevel image segmentation is a critical task in image analysis,which imposes high requirements on the global search capability and convergence efficiency of segmentation algorithms.In this paper,an improved Artificial Protozoa Optimization algorithm,termed the two-stage Taguchi-assisted Gaussian–Levy Artificial Protozoa Optimization(TGAPO)algorithm,is proposed and applied tomultilevel image segmentation.The proposed algorithm adopts a two-stage evolutionary mechanism.In the first stage,Gaussian perturbation is introduced to enhance local search capability;in the second stage,Levy flight is incorporated to expand the global search range;and finally,the Taguchi strategy is employed to further refine the optimal solution.Consequently,the global optimization performance and robustness of the algorithm are significantly improved.To evaluate the effectiveness of the proposed TGAPO algorithm,comparative experiments are conducted with representative optimization algorithms,including the Grey Wolf Optimizer(GWO)and Particle Swarm Optimization(PSO),in the context ofmultilevel image segmentation.The segmentation quality is assessed using the minimum cross-entropy function as the performance metric.Experimental results demonstrate that the TGAPO algorithm outperforms the comparison algorithms in terms of segmentation accuracy and convergence speed,and exhibits superior stability in high-threshold segmentation tasks.Furthermore,the proposedmethod achieves excellentmulti-threshold segmentation performance for color images and shows strong potential for practical applications.
文摘Sleep is a biological phenomenon with highly conserved evolutionary characteristics.The American Academy of Sleep Medicine and the Sleep Research Society recommend that adults get at least 7 hours of sleep per night[1].However,the stress caused by fast-paced life often leads to sleep deprivation(SD).SD is strongly associated with damage to the auditory system[2,3].Obstructive sleep apnea-hypopnea syndrome(OSAHS)is a common sleep disorder.Clinical observations indicate that some patients with OSAHS experience persistent hearing loss accompanied by tinnitus and other symptoms[4].More than 61.8%of patients with sudden deafness experienced SD[5].
基金Supported by the National Key Research and Development Program of China(2023YFD1400502)。
文摘To investigate the eco-economic thresholds of weeds and the critical period for their control,combining economic and ecological perspectives to achieve scientific weed management,four dominant weeds,Echinochloa crus-galli(L.)P.Beauv,Chenopodium album L.,Digitaria sanguinalis(L.)Scop,and Commelina communis L.,were selected as experimental subjects,based on their common occurrence in spring maize planting areas in Northern China.A predictive model for maize yield loss caused by mixed weed populations was established.The study analyzed the eco-economic thresholds of weeds under different control measures and determined the optimal period for weed control by combining the critical control period.A logarithmic function model was developed to describe the relationship between mixed weed density and maize yield loss:y=5.9875ln(x)-6.5407(R^(2)=0.949,F=131.244,P=0.000).The optimal model for the critical period of competition between weeds and maize in maize fields was:y=-0.0027x^(2)+0.5624x-10.064(R2=0.968,F=30.513,P=0.032).When the weed density in maize fields reached 5.57 plants·m^(-2),manual weeding should be conducted promptly.When the weed density was 3.41 plants·m^(-2) or 3.48 plants·m^(-2),soil or foliar treatments should be applied,respectively.If the weed density reached 3.93 plants·m^(-2),a combination of soil and foliar treatment should be implemented.The critical period for manual weeding was 28.4 days after sowing,for soil treatment it was 19.9 days,for foliar treatment it was 21.8 days,and for the combined treatment of soil and foliar methods,it was 23.5 days after sowing.Retaining weeds for up to 15 days after maize sowing did not result in a yield loss and could even have a positive effect on maize yield.
文摘Objective To investigate changes that occur in the brain when the physiological convulsive threshold becomes pathological,and to determine what differences occur in pathological and physiological convulsive thresholds during the development of epilepsy. Methods In this study,the threshold for convulsions was determined by direct cortical stimulation in rats.The convulsive threshold was measured while recording electroencephalograms and subsequently examining histopathological changes in the hippocampus. Results At the beginning of the experiment,convulsive thresholds were all above 1 100 μA although there were significant individual variations in rats of the same group.But those thresholds quickly declined during the initial 4 weeks of repetitive electrical stimulation.The convulsive thresholds approached a constant level[TLS(430±34)μA,TGS(480±46)μA,TPS(605±70)μA]in the 10th week.There were no significant changes in thresholds when stimulation lasted for longer,the convulsive thresholds and the variations in rats of the same group were significantly lower than that at the beginning of the trial(P<0.01).An interictal discharge was also recorded in the 3rd week in heavy current group and at the 8th week in weak current group respectively which were concomitant with the neuronal da-mage and loss in the hippocampus.There was no abnormality observed in control group. Conclusion These findings indicate that the convulsion threshold in the brain should be divided into two stages:physiological convulsive threshold and pathological convulsive threshold(epileptic threshold).Epileptic threshold is created by pathological acquired factors which give rise to brain damage.The intensity of these pathological acquired factors is correlated with the formation of the pathological convulsive threshold.
基金support of the National Natural Science Foundation of China (41271490, 21077131)
文摘It is imperative to derive an appropriate cadmium (Cd) health risk toxicity threshold for paddy soils to ensure the Cd con-centration of rice grains meet the food safety standard. In this study, 20 rice cultivars from the main rice producing areas in China were selected, and a pot-experiment was conducted to investigate transformation of Cd in paddy soil-rice system with 0 (CK), 0.3 mg kg–1 (T1) and 0.6 mg kg–1 (T2) Cd treatments in greenhouse. The results showed that Cd concentrations of rice grains existed signiifcant difference (P<0.05) in 20 rice cultivars under the same Cd level in soil. The Cd concentrations of rice grains of the CK, T1 and T2 treatments were in the range of 0.143–0.202, 0.128–0.458 and 0.332–0.806 mg kg–1, respectively. Marked differences of the ratios of Cd concentration for soil to rice grain (BCFs) and transfer factors (TFs, root to grain and straw to grain) among the tested cultivars were observed in this study. The bioconcentration factors (BCFgrain) and TFs of the 20 rice cultivars were 0.300–1.112 and 0.342–0.817, respectively. The TFs of Cd from straw to grain ranged from 0.366 to 1.71, with signiifcant differences among these 20 rice cultivars. The bioconcentration factors (BCFgrain) and TFs among the 20 rice cultivars ranged from 0.300–1.112 and 0.342–0.817, respectively. The species-sensitivity distribu-tion (SSD) of Cd sensitivity of the rice species could be iftted wel with Burr-III (R2=0.987) based on the data of BCFs. The toxicity threshold of Cd derived from SSD for the paddy soil was 0.507 mg kg–1 in the present study.
基金supported by the National Nature Science Foundation of China (31360502)the Pre-973 Project of China (2012CB126307)the Inner Mongolia Nature Science Foundation, China (2013ZD04)
文摘The hand-held soil plant analysis development （SPAD） chlorophyll meter nitrogen status of the potato and guiding fertilization recommendations N recommendation, it is critical to establish the threshold SPAD value has proved to be a promising tool in evaluating the n the process of N evaluation of potato plants and （SPAD reading）, below which nitrogen supplement is required. And taking convenient using into account, the threshold needs to be dynamic throughout the potato growing season so that the users can test their potato plants and make fertilization decision at any growing time of potato. To complete this goal, field experiments with different nitrogen supply levels were conducted in different sites in northern China from 2009 to 2011. The results showed that threshold SPAD values decrease as the growing season progresses for all cultivars and planting sites. By statistical analysis, the threshold regression models were established respectively as： y=-0.003χ2-0.0507χ＋58.213 （y, threshold SPAD value; χ, days after emergence） for the potato cultivar Kexin 1, and y=-0.003χ2＋0.017χ＋52.489 （y, threshold SPAD value; χ, days after emergence） for the cultivar Shepody, from which, the threshold SPAD value at any day after emergence can be calculated.
基金supported by the National Natural Science Foundation of China(Grant Nos.42077232 and 42077235)the Key Research and Development Plan of Jiangsu Province(Grant No.BE2022156).
文摘The influences of biological,chemical,and flow processes on soil structure through microbially induced carbonate precipitation(MICP)are not yet fully understood.In this study,we use a multi-level thresholding segmentation algorithm,genetic algorithm(GA)enhanced Kapur entropy(KE)(GAE-KE),to accomplish quantitative characterization of sandy soil structure altered by MICP cementation.A sandy soil sample was treated using MICP method and scanned by the synchrotron radiation(SR)micro-CT with a resolution of 6.5 mm.After validation,tri-level thresholding segmentation using GAE-KE successfully separated the precipitated calcium carbonate crystals from sand particles and pores.The spatial distributions of porosity,pore structure parameters,and flow characteristics were calculated for quantitative characterization.The results offer pore-scale insights into the MICP treatment effect,and the quantitative understanding confirms the feasibility of the GAE-KE multi-level thresholding segmentation algorithm.
文摘Penile hypersensitivity plays an important role in premature ejaculation （PE）, but differences in penile sensitivity among subtypes of PE are unknown. Therefore, we compared penile sensory thresholds in PE subtypes of lifelong and acquired PE, PE with and without erectile dysfunction （ED）, PE with an intravaginal ejaculation latency time 〈1 min and 〉1 min, and PE with and without orgasmic pleasure perceptual dysfunction. During August 2014 to January 2016, 136 patients with PE were included. Penile warm, cold, and vibratory thresholds were measured. Data of clinical characteristics, sexual life, Premature Ejaculation Diagnostic Tool （PEDT） score, and the 5-item version of the International Index of Erectile Function （IIEF-5） score were collected. Vibratory thresholds of the PE with ED group were higher in the right coronal sulcus （median amplitude： 4.92 vs 3.65 μm, P= 0.02） and the right penile shaft （median amplitude： 3.87 vs 3.30 μm, P = 0.03）, while differences in penile sensory thresholds between other subtypes were not significant. The median PEDT score was lower in the PE without ED group （12 vs 14, P 〈 0.001）. The IIEF-5 and PEDT scores were negatively correlated （r = -0.29, P 〈 0.001）. Patients with orgasmic pleasure perceptual dysfunction had a lower median IIEF-5 score （20 vs 21, P = 0.02）. Patients with PE and ED had lower penile sensitivity, and ED was associated with more severe symptoms and weaker orgasmic pleasure perception. In men with PE, management of comorbid ED is necessary. In case of side effects in erectile function, topical anesthetics should be cautiously used in men with PE and ED.
