Based on the keynote report by Professor Martin Thrupp,this paper discusses the hollowing out of education provision by the state and the permeation of managerialism.It was pointed out that principals and boards of tr...Based on the keynote report by Professor Martin Thrupp,this paper discusses the hollowing out of education provision by the state and the permeation of managerialism.It was pointed out that principals and boards of trustees in socioeconomically advantaged areas may not be willing to share their benefits with schools in less advantaged areas.The new liberal policies have hollowed out state provision of education,so the education system has come to rely heavily on private actors.This paper also presents the current stage of privatization in Japan and the principals’and teachers’perceptions of privatization.展开更多
The purpose of this research is to investigate the principals’stress and coping strategies to deal with stress by principals in Bedouin schools in Israel.Data were collected in this research by combining a quantitati...The purpose of this research is to investigate the principals’stress and coping strategies to deal with stress by principals in Bedouin schools in Israel.Data were collected in this research by combining a quantitative and qualitative mixed method.A quantitative research questionnaire was conducted for school principals in 36 schools,in addition to an interview with three principals based on the causes of principal stress and coping mechanisms.Research results show that the principals experiencing balance had the highest mean(M)of 3.28 and standard deviation(SD)of 1.64 on a five-point scale.Principals experiencing moderate stress was parents(M=3.10,SD=0.57)and teachers(M=3.14,SD=0.54),while workload had the lowest mean(M=2.97,SD=0.64).展开更多
Rural boarding schools in compulsory education in China have proliferated with school merger program.This paper analyzes the relationship between school belonging and student development and the factors that influence...Rural boarding schools in compulsory education in China have proliferated with school merger program.This paper analyzes the relationship between school belonging and student development and the factors that influence students'sense of belonging in rural boarding schools.The paper examines how principals in rural boarding schools in China can promote student development by building a sense of belonging.The paper argues that building this sense of belonging can serve as a solution to the current problems affecting rural boarding schools,improve the quality of rural primary education,and promote student development.展开更多
Joint roughness coefficient(JRC)is the most commonly used parameter for quantifying surface roughness of rock discontinuities in practice.The system composed of multiple roughness statistical parameters to measure JRC...Joint roughness coefficient(JRC)is the most commonly used parameter for quantifying surface roughness of rock discontinuities in practice.The system composed of multiple roughness statistical parameters to measure JRC is a nonlinear system with a lot of overlapping information.In this paper,a dataset of eight roughness statistical parameters covering 112 digital joints is established.Then,the principal component analysis method is introduced to extract the significant information,which solves the information overlap problem of roughness characterization.Based on the two principal components of extracted features,the white shark optimizer algorithm was introduced to optimize the extreme gradient boosting model,and a new machine learning(ML)prediction model was established.The prediction accuracy of the new model and the other 17 models was measured using statistical metrics.The results show that the prediction result of the new model is more consistent with the real JRC value,with higher recognition accuracy and generalization ability.展开更多
A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states...A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.展开更多
Dysregulation of neurotransmitter metabolism in the central nervous system contributes to mood disorders such as depression, anxiety, and post–traumatic stress disorder. Monoamines and amino acids are important types...Dysregulation of neurotransmitter metabolism in the central nervous system contributes to mood disorders such as depression, anxiety, and post–traumatic stress disorder. Monoamines and amino acids are important types of neurotransmitters. Our previous results have shown that disco-interacting protein 2 homolog A(Dip2a) knockout mice exhibit brain development disorders and abnormal amino acid metabolism in serum. This suggests that DIP2A is involved in the metabolism of amino acid–associated neurotransmitters. Therefore, we performed targeted neurotransmitter metabolomics analysis and found that Dip2a deficiency caused abnormal metabolism of tryptophan and thyroxine in the basolateral amygdala and medial prefrontal cortex. In addition, acute restraint stress induced a decrease in 5-hydroxytryptamine in the basolateral amygdala. Additionally, Dip2a was abundantly expressed in excitatory neurons of the basolateral amygdala, and deletion of Dip2a in these neurons resulted in hopelessness-like behavior in the tail suspension test. Altogether, these findings demonstrate that DIP2A in the basolateral amygdala may be involved in the regulation of stress susceptibility. This provides critical evidence implicating a role of DIP2A in affective disorders.展开更多
Restoration of phase aberrations is crucial for addressing atmospheric turbulence in light propagation.Traditional restoration algorithms based on Zernike polynomials(ZPs)often encounter challenges related to high com...Restoration of phase aberrations is crucial for addressing atmospheric turbulence in light propagation.Traditional restoration algorithms based on Zernike polynomials(ZPs)often encounter challenges related to high computational complexity and insufficient capture of high-frequency phase aberration components,so we proposed a Principal-Component-Analysis-based method for representing phase aberrations.This paper discusses the factors influencing the accuracy of restoration,mainly including the sample space size and the sampling interval of D/r_(0),on the basis of characterizing phase aberrations by Principal Components(PCs).The experimental results show that a larger D/r_(0)sampling interval can ensure the generalization ability and robustness of the principal components in the case of a limited amount of original data,which can help to achieve high-precision deployment of the model in practical applications quickly.In the environment with relatively strong turbulence in the test set of D/r_(0)=24,the use of 34 terms of PCs can improve the corrected Strehl ratio(SR)from 0.007 to 0.1585,while the Strehl ratio of the light spot after restoration using 34 terms of ZPs is only 0.0215,demonstrating almost no correction effect.The results indicate that PCs can serve as a better alternative in representing and restoring the characteristics of atmospheric turbulence induced phase aberrations.These findings pave the way to use PCs of phase aberrations with fewer terms than traditional ZPs to achieve data dimensionality reduction,and offer a reference to accelerate and stabilize the model and deep learning based adaptive optics correction.展开更多
This paper reports findings from a comparative study of urban vs.rural school principals in China.It is an extension and replication of an earlier study on the profiles and preparation of school leaders in the US and ...This paper reports findings from a comparative study of urban vs.rural school principals in China.It is an extension and replication of an earlier study on the profiles and preparation of school leaders in the US and China.The study illustrates modern portraits-demographic characteristics of urban and rural principals in China,explores their entry perspectives and examines their professional commitment to principalship as a lifelong career.Findings from the comparative study indicate that urban and rural school principals in China differ greatly in their profiles and characteristics.They share similar intrinsic or extrinsic reasons for becoming principals,but they also vary on some key reasons.Unfortunately,most of the principals in our study are not firmly committed to principalship as a lifelong career because of a range of disturbing factors.Findings from this study shed new light on the profiles and preparation of educational leaders in China and offer thoughtful recommendations for change to both Chinese and international education community.展开更多
The principal stresses will increase or decrease during mining,leading to variations in surrounding rock strength and subsequently an influence on the risk of rockbursts.To address this issue,this study conducted theo...The principal stresses will increase or decrease during mining,leading to variations in surrounding rock strength and subsequently an influence on the risk of rockbursts.To address this issue,this study conducted theoretical analysis,numerical simulation,and field monitoring.A rockburst risk analysis method that integrates dynamic changes in the stress and strength of surrounding rock was proposed and verified in the field.The dynamic changes in maximum(σ_(1))and minimum(σ_(3))principal stresses are represented by the σ_(1) and σ_(3) differentials,respectively.The difference in principal stress differential(DPSD),defined as the difference between σ_(1) and σ_(3),was introduced as a novel indicator for rockburst risk analysis.The findings of this study demonstrate a positive correlation between increases in DPSD and heightened risks of rockbursts,as evidenced by an increase in both the frequency of rockbursts and the occurrence of large-energy microseismic events.Conversely,a decrease in DPSD is associated with a reduction in risk.Specifically,in the W1123 panel of a coal mine susceptible to rockbursts,areas exhibiting higher DPSD values experienced more frequent and severe rockbursts.The DPSD-based analysis aligned well with the observed rockburst occurrences.Subsequent optimization of rockburst prevention measures in areas with elevated DPSD led to a reduction in DPSD.Following these adjustments,the W1123 panel predominantly experienced low-energy microseismic events,with a significant decrease in large-energy microseismic events and no further rockbursts.The DPSD analysis is a valuable tool for evaluating rockburst risk and aiding in prevention,which is of great significance for disaster prevention.展开更多
Fracture(fault)reactivation can lead to dynamic geological hazards including earthquakes,rock collapses,landslides,and rock bursts.True triaxial compression tests were conducted to analyze the fracture reactivation pr...Fracture(fault)reactivation can lead to dynamic geological hazards including earthquakes,rock collapses,landslides,and rock bursts.True triaxial compression tests were conducted to analyze the fracture reactivation process under two different orientations of σ_(2),i.e.σ_(2) parallel to the fracture plane(Scheme 2)and σ_(2) cutting through the fracture plane(Scheme 3),under varying σ_(3) from 10 MPa to 40 MPa.The peak or fracture reactivation strength,deformation,failure mode,and post-peak mechanical behavior of intact(Scheme 1)and pre-fractured(Schemes 2 and 3)specimens were also compared.Results show that for intact specimens,the stress remains nearly constant in the residual sliding stage with no stick-slip,and the newly formed fracture surface only propagates along the σ_(2) direction when σ_(3) ranges from 10 MPa to 30 MPa,while it extends along both σ_(2) and σ_(3) directions when σ_(3) increases to 40 MPa;for the pre-fractured specimens,the fractures are usually reactivated under all the σ_(3) levels in Scheme 2,but fracture reactivation only occurs when σ_(3) is greater than 25 MPa in Scheme 3,below which new faulting traversing the original macro fracture occurs.In all the test schemes,both ε_(2) and ε_(3) experience an accumulative process of elongation,after which an abrupt change occurs at the point of the final failure;the degree of this change is dependent on the orientation of the new faulting or the slip direction of the original fracture,and it is generally more than 10 times larger in the slip direction of the original fracture than in the non-slip direction.Besides,the differential stress(peak stress)required for reactivation and the post-peak stress drop increase with increasing σ_(3).Post-peak stress drop and residual strength in Scheme 3 are generally greater than those in Scheme 2 at the same σ_(3) value.Our study clearly shows that intermediate principal stress orientation not only affects the fracture reactivation strength but also influences the slip deformation and failure modes.These new findings facilitate the mitigation of dynamic geological hazards associated with fracture and fault slip.展开更多
Aspergillus species produce aflatoxins and raise concerns about food safety in departmental stores and manufacturing mills.To address the risks posed by aflatoxins,and to advise the public on the highest quality rice ...Aspergillus species produce aflatoxins and raise concerns about food safety in departmental stores and manufacturing mills.To address the risks posed by aflatoxins,and to advise the public on the highest quality rice that serves as a nutritious food source,an inquiry following the guidelines outlined in both local and international standards of food safety for the presence of aflatoxins is an essential requirement.Therefore,16 white rice samples were selected randomly from low/high socio-economic departmental stores from 16 different localities.Grind powdered rice filtrate was extracted using chloroform.The filtrate applied on TLC plates and the amount of aflatoxin and moisture contents were determined.In the non-infected rice,moisture content was low(9.08%)whereas high[13.65%>12%(standard>value)]in infected ones.Four out of 8 samples of low-quality rice were contaminated with AFB_(1) and AFB_(2)(ranging from 22.2 to 29.3μg/kg).All the samples except one(22.3μg/kg)from high-quality rice were certified fit despite the contamination with AFB_(1).Furthermore,phylogenetic analysis showed Aspergillus flavus from unfit low(Long grain brown and Brown basmati)and high-quality(Basmati-198)rice whereas A.parasiticus from unfit low-quality Medium-grain brown rice.The presented research proves that the detection of fungi and aflatoxins in rice grains poses a huge risk to the health of consumers.Therefore,it is necessary to check the rice grains before distribution.展开更多
[Objectives]To investigate the content and distribution of inorganic elements in Astragalus membranaceus sourced from various regions in Gansu Province.[Methods]28 batches of A.membranaceus samples were collected and ...[Objectives]To investigate the content and distribution of inorganic elements in Astragalus membranaceus sourced from various regions in Gansu Province.[Methods]28 batches of A.membranaceus samples were collected and subsequently digested using the Multiwave 7000 super microwave digestion system.The contents of aluminum(Al),barium(Ba),beryllium(Be),cobalt(Co),chromium(Cr),iron(Fe),gallium(Ga),magnesium(Mg),manganese(Mn),nickel(Ni),antimony(Sb),tin(Sn),strontium(Sr),titanium(Ti),thallium(Tl),vanadium(V),and zinc(Zn)were quantified utilizing a PerkinElmer 2000 inductively coupled plasma mass spectrometer.Principal component analysis was performed utilizing SPSS 25.0 to identify the distinctive characteristic elements of A.membranaceus.Additionally,systematic cluster analysis was conducted using these characteristic elements as variables to investigate the relationship between the primary inorganic elements and the geographical origin of A.membranaceus.[Results]17 inorganic elements were identified in A.membranaceus specimens collected from Gansu Province,with characteristic elements including Ba,Co,Fe,Ga,Mn,Zn,and Sn.The contents of inorganic elements in various sources of A.membranaceus exhibited significant variability and demonstrated distinct clustering characteristics.[Conclusions]A.membranaceus,originating from Gansu Province,exhibits a high content of inorganic elements.However,variations in ecological environments can lead to differences in the specific inorganic elements that are enriched.This study aims to provide a reference for the further development and application of A.membranaceus.展开更多
Multiple principal element alloys(MPEAs),also known as high-entropy alloys,have attracted significant attention because of their exceptional mechanical and thermal properties.A critical factor influencing these proper...Multiple principal element alloys(MPEAs),also known as high-entropy alloys,have attracted significant attention because of their exceptional mechanical and thermal properties.A critical factor influencing these properties is suggested to be the presence of chemical short-range order(SRO),characterized by specific atomic arrangements occurring more frequently than in a random distribution.Despite extensive efforts to elucidate SRO,particularly in face-centered cubic(fcc)3d transition metal-based MPEAs,several key aspects remain under debate:the conditions under which SRO forms,the reliability of characterization methods for detecting SRO,and its quantitative impact on mechanical performance.This review summarizes the challenges and unresolved issues in this emerging field,drawing comparisons with well-established research on SRO in binary alloys over the past few decades.Through this cross-system comparison,we aim to provide new insights into SRO from a comprehensive perspective.展开更多
This paper explores the relationship between leader values and actions in the Chinese context.The Chinese Value Instrument(CVI)and the Strategic Leadership Questionnaire(SLQ)were used as the primary data collection to...This paper explores the relationship between leader values and actions in the Chinese context.The Chinese Value Instrument(CVI)and the Strategic Leadership Questionnaire(SLQ)were used as the primary data collection tools.The CVI was used to measure the presence of ten values:(1)social harmony,(2)benevolence and honesty,(3)initiative and innovation(challenge and creativity),(4)achievement and power,(5)zhongyong(practicality and modesty),(6)stability,(7)familial loyalty,(8)happiness,(9)renqing(sympathy)and guanxi(personal relationships),and(10)freedom and equity.The findings indicate that achievement and initiative were at the low end of the value continuum.Familial loyalty,social harmony,and benevolence were at the high end of the value continuum.The SLQ measured the managing,transforming,bonding,bridging,and bartering actions leaders use to mobilize and gain support from followers.The findings indicate that the Chinese school principal management prototype is formed around transforming and bonding actions.This prototype changes depending on role assignment and school type.A connection between leader values and actions was established with regard to the values of achievement and power,benevolence and honesty,and stability.展开更多
This paper reviews the history and lessons of global oil crises while exploring the establishment of a quantitative evaluation model for oil security with Chinese characteristics.Using principal component analysis,it ...This paper reviews the history and lessons of global oil crises while exploring the establishment of a quantitative evaluation model for oil security with Chinese characteristics.Using principal component analysis,it constructs an oil security evaluation indicator system for China with two main-level indicators:foreign oil dependency and its impacts,and market intervention and security assurance.展开更多
Damming is a major geomorphological event characterized by catastrophic consequences and profound impacts on fluvial landscape evolution.Extensive Quaternary detrital deposits(DD)have been discovered in the Daju Basin...Damming is a major geomorphological event characterized by catastrophic consequences and profound impacts on fluvial landscape evolution.Extensive Quaternary detrital deposits(DD)have been discovered in the Daju Basin.Some research suggests that these deposits are potentially associated with Great Flood events in the mainstream region.However,considering the multiplicity and complexity of the deposition,they may also result from catastrophic debris flows in local gullies.Consequently,we conducted a comprehensive investigation of detrital deposits and collected 64 provenance samples.The sediment provenance was analyzed by grain size distribution and elemental composition characterization.The results are as follows:(1)The detrital deposits in the basin are predominantly composed of sand and gravel,with some clay.(2)The results of the elemental ratios and multivariate statistical analysis confirmed the similarity in material composition between the detrital deposits in the basin and those from the Muduoluo Gully.(3)The discovery of palaeolandslides and lacustrine deposits in the study area indicates the existence of ancient dammed lakes and historical river damming events.The detrital deposits likely represent fan delta sediments formed by water-land interactions caused by damming events.Our study highlights new insights into discriminating the provenances of detrital deposits in localized regions,providing a new perspective for investigating geological hazards in the Jinsha River Basin.展开更多
The Global Navigation Satellite System(GNSS)is vital for monitoring terrestrial water storage(TWS).However,effectively extracting hydrological load deformation from GNSS observations poses a significant challenge.This...The Global Navigation Satellite System(GNSS)is vital for monitoring terrestrial water storage(TWS).However,effectively extracting hydrological load deformation from GNSS observations poses a significant challenge.This study proposes a novel strategy;the seasonal hydrological load signals are removed from the raw data,and the remaining signals use principal component analysis(PCA).Simulation results from Yunnan Province demonstrate that the spatial distribution of the root mean square error(RMSE)is improved by approximately 15% compared with traditional PCA extraction from raw data.From January 2013 to December 2022,TWS was inverted from 24 GNSS stations in Yunnan Province.The spatial distribution and time series of TWS inverted from GNSS align well with those TWS inferred from the Gravity Recovery and Climate Experiment(GRACE),GRACE Follow-On(GFO),and the Global Land Data Assimilation System(GLDAS)land surface model.However,the amplitude of the GNSS-inverted TWS is slightly higher.Since GNSS ground stations are more sensitive to hydrological load signals,they show correlations with precipitation data that are 8.6%and 6.0%higher than those of GRACE and GLDAS,respectively.In the power spectral density analysis of GRACE/GFO,GLDAS,and GNSS,the signal strength of GNSS is much higher than that of GRACE/GFO and GLDAS in the June and February cycles.These findings suggest that the new data extraction strategy can capture higher frequency hydrological signals in TWS,and GNSS observations can help address limitations in GRACE/GFO observations.This study demonstrates the potential of GNSS TWS in capturing higher-frequency hydrological signals and climate extremes application.展开更多
Purpose:This study analyzes the profiles of elite Brazilian researchers,recognized through the prestigious CNPq productivity scholarships.By identifying distinct researcher clusters,the study sheds light on different ...Purpose:This study analyzes the profiles of elite Brazilian researchers,recognized through the prestigious CNPq productivity scholarships.By identifying distinct researcher clusters,the study sheds light on different academic strategies,levels of productivity,and academic contributions within the Brazilian higher education system.Design/methodology/approach:The research analyzes a comprehensive dataset of 14,003 researchers,employing principal component analysis(PCA)followed by cluster analysis to group researchers based on their academic attributes.The clusters reflect diverse aspects of research productivity,graduate supervisions,and publication patterns.Findings:The analysis reveals the existence of three distinct researcher profiles(the Advanced Supervisors,the Book Publishers/Organizers,and the Generalists).The study also highlights the characteristics of highcaliber scientists,representing the upper echelon of Brazilian researchers in terms of productivity and impact.Research limitations:Although the study provides a robust analysis of the Brazilian system,the results reflect specific characteristics of the Brazilian academic context.Furthermore,the analysis was restricted to normalized annual data,which may overlook temporal variations in researcher productivity.Pratical implications:The findings provide valuable insights for policy makers,funding agencies(such as CNPq),and university administrators who aim to develop tailored support programs for different researcher profiles.Originality/value:The cluster-based profiling offers a novel perspective on how different academic trajectories coexist within a national science system,offering lessons for other emerging economies.展开更多
The basement aquifers in Burkina Faso are increasingly exposed to groundwater pollution,largely due to socio-economic activities and climatic fluctuations,particularly the reduction in rainfall.This pollution makes th...The basement aquifers in Burkina Faso are increasingly exposed to groundwater pollution,largely due to socio-economic activities and climatic fluctuations,particularly the reduction in rainfall.This pollution makes the management and understanding of these aquifers particularly complex.To elucidate the processes controlling this contamination,a methodological approach combining principal component analysis(PCA)and multivariate statistical techniques was adopted.The study analyzed sixteen physicochemical parameters from 58 water samples.The primary objective of this research is to assess groundwater quality and deepen the understanding of the key factors influencing the spatial variation of their chemical composition.The results obtained will contribute to better planning of preservation and sustainable management measures for water resources in Burkina Faso.The results show that three principal components explain 72%of the variance,identifying anthropogenic inputs,with two components affected by mineralization and one by pollution.The study reveals that the groundwater is aggressive and highly corrosive,with calcite saturation.Water-rock interactions appear to be the main mechanisms controlling the hydrochemistry of groundwater,with increasing concentrations of cations and anions as the water travels through percolation pathways.PCA also revealed that the residence time of the water and leaching due to human activities significantly influence water quality,primarily through mineralization processes.These results suggest that rock weathering,coupled with reduced rainfall,constitutes a major vulnerability for aquifer recharge.展开更多
文摘Based on the keynote report by Professor Martin Thrupp,this paper discusses the hollowing out of education provision by the state and the permeation of managerialism.It was pointed out that principals and boards of trustees in socioeconomically advantaged areas may not be willing to share their benefits with schools in less advantaged areas.The new liberal policies have hollowed out state provision of education,so the education system has come to rely heavily on private actors.This paper also presents the current stage of privatization in Japan and the principals’and teachers’perceptions of privatization.
文摘The purpose of this research is to investigate the principals’stress and coping strategies to deal with stress by principals in Bedouin schools in Israel.Data were collected in this research by combining a quantitative and qualitative mixed method.A quantitative research questionnaire was conducted for school principals in 36 schools,in addition to an interview with three principals based on the causes of principal stress and coping mechanisms.Research results show that the principals experiencing balance had the highest mean(M)of 3.28 and standard deviation(SD)of 1.64 on a five-point scale.Principals experiencing moderate stress was parents(M=3.10,SD=0.57)and teachers(M=3.14,SD=0.54),while workload had the lowest mean(M=2.97,SD=0.64).
文摘Rural boarding schools in compulsory education in China have proliferated with school merger program.This paper analyzes the relationship between school belonging and student development and the factors that influence students'sense of belonging in rural boarding schools.The paper examines how principals in rural boarding schools in China can promote student development by building a sense of belonging.The paper argues that building this sense of belonging can serve as a solution to the current problems affecting rural boarding schools,improve the quality of rural primary education,and promote student development.
基金funding from the National Natural Science Foundation of China (Grant No.42277175)the pilot project of cooperation between the Ministry of Natural Resources and Hunan Province“Research and demonstration of key technologies for comprehensive remote sensing identification of geological hazards in typical regions of Hunan Province” (Grant No.2023ZRBSHZ056)the National Key Research and Development Program of China-2023 Key Special Project (Grant No.2023YFC2907400).
文摘Joint roughness coefficient(JRC)is the most commonly used parameter for quantifying surface roughness of rock discontinuities in practice.The system composed of multiple roughness statistical parameters to measure JRC is a nonlinear system with a lot of overlapping information.In this paper,a dataset of eight roughness statistical parameters covering 112 digital joints is established.Then,the principal component analysis method is introduced to extract the significant information,which solves the information overlap problem of roughness characterization.Based on the two principal components of extracted features,the white shark optimizer algorithm was introduced to optimize the extreme gradient boosting model,and a new machine learning(ML)prediction model was established.The prediction accuracy of the new model and the other 17 models was measured using statistical metrics.The results show that the prediction result of the new model is more consistent with the real JRC value,with higher recognition accuracy and generalization ability.
基金supports from the National Natural Science Foundation of China (Grant Nos.52004143 and 52374095)the open fund for the Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines (Grant No.SKLMRDPC21KF06).
文摘A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.
基金supported by the STI 2030—Major Projects 2021ZD0204000,No.2021ZD0204003 (to XZ)the National Natural Science Foundation of China,Nos.32170973 (to XZ),32071018 (to ZH)。
文摘Dysregulation of neurotransmitter metabolism in the central nervous system contributes to mood disorders such as depression, anxiety, and post–traumatic stress disorder. Monoamines and amino acids are important types of neurotransmitters. Our previous results have shown that disco-interacting protein 2 homolog A(Dip2a) knockout mice exhibit brain development disorders and abnormal amino acid metabolism in serum. This suggests that DIP2A is involved in the metabolism of amino acid–associated neurotransmitters. Therefore, we performed targeted neurotransmitter metabolomics analysis and found that Dip2a deficiency caused abnormal metabolism of tryptophan and thyroxine in the basolateral amygdala and medial prefrontal cortex. In addition, acute restraint stress induced a decrease in 5-hydroxytryptamine in the basolateral amygdala. Additionally, Dip2a was abundantly expressed in excitatory neurons of the basolateral amygdala, and deletion of Dip2a in these neurons resulted in hopelessness-like behavior in the tail suspension test. Altogether, these findings demonstrate that DIP2A in the basolateral amygdala may be involved in the regulation of stress susceptibility. This provides critical evidence implicating a role of DIP2A in affective disorders.
文摘Restoration of phase aberrations is crucial for addressing atmospheric turbulence in light propagation.Traditional restoration algorithms based on Zernike polynomials(ZPs)often encounter challenges related to high computational complexity and insufficient capture of high-frequency phase aberration components,so we proposed a Principal-Component-Analysis-based method for representing phase aberrations.This paper discusses the factors influencing the accuracy of restoration,mainly including the sample space size and the sampling interval of D/r_(0),on the basis of characterizing phase aberrations by Principal Components(PCs).The experimental results show that a larger D/r_(0)sampling interval can ensure the generalization ability and robustness of the principal components in the case of a limited amount of original data,which can help to achieve high-precision deployment of the model in practical applications quickly.In the environment with relatively strong turbulence in the test set of D/r_(0)=24,the use of 34 terms of PCs can improve the corrected Strehl ratio(SR)from 0.007 to 0.1585,while the Strehl ratio of the light spot after restoration using 34 terms of ZPs is only 0.0215,demonstrating almost no correction effect.The results indicate that PCs can serve as a better alternative in representing and restoring the characteristics of atmospheric turbulence induced phase aberrations.These findings pave the way to use PCs of phase aberrations with fewer terms than traditional ZPs to achieve data dimensionality reduction,and offer a reference to accelerate and stabilize the model and deep learning based adaptive optics correction.
文摘This paper reports findings from a comparative study of urban vs.rural school principals in China.It is an extension and replication of an earlier study on the profiles and preparation of school leaders in the US and China.The study illustrates modern portraits-demographic characteristics of urban and rural principals in China,explores their entry perspectives and examines their professional commitment to principalship as a lifelong career.Findings from the comparative study indicate that urban and rural school principals in China differ greatly in their profiles and characteristics.They share similar intrinsic or extrinsic reasons for becoming principals,but they also vary on some key reasons.Unfortunately,most of the principals in our study are not firmly committed to principalship as a lifelong career because of a range of disturbing factors.Findings from this study shed new light on the profiles and preparation of educational leaders in China and offer thoughtful recommendations for change to both Chinese and international education community.
基金support from the National Natural Science Foundation of China(Grant Nos.52374180 and 52327804).
文摘The principal stresses will increase or decrease during mining,leading to variations in surrounding rock strength and subsequently an influence on the risk of rockbursts.To address this issue,this study conducted theoretical analysis,numerical simulation,and field monitoring.A rockburst risk analysis method that integrates dynamic changes in the stress and strength of surrounding rock was proposed and verified in the field.The dynamic changes in maximum(σ_(1))and minimum(σ_(3))principal stresses are represented by the σ_(1) and σ_(3) differentials,respectively.The difference in principal stress differential(DPSD),defined as the difference between σ_(1) and σ_(3),was introduced as a novel indicator for rockburst risk analysis.The findings of this study demonstrate a positive correlation between increases in DPSD and heightened risks of rockbursts,as evidenced by an increase in both the frequency of rockbursts and the occurrence of large-energy microseismic events.Conversely,a decrease in DPSD is associated with a reduction in risk.Specifically,in the W1123 panel of a coal mine susceptible to rockbursts,areas exhibiting higher DPSD values experienced more frequent and severe rockbursts.The DPSD-based analysis aligned well with the observed rockburst occurrences.Subsequent optimization of rockburst prevention measures in areas with elevated DPSD led to a reduction in DPSD.Following these adjustments,the W1123 panel predominantly experienced low-energy microseismic events,with a significant decrease in large-energy microseismic events and no further rockbursts.The DPSD analysis is a valuable tool for evaluating rockburst risk and aiding in prevention,which is of great significance for disaster prevention.
基金funding support from the National Nature Science Foundation of China(Grant No.42272334)the National Key Research and Development Program of China(Grant No.2022YFE0137200)the Taishan Scholars Program(Grant No.2019RKB01083).
文摘Fracture(fault)reactivation can lead to dynamic geological hazards including earthquakes,rock collapses,landslides,and rock bursts.True triaxial compression tests were conducted to analyze the fracture reactivation process under two different orientations of σ_(2),i.e.σ_(2) parallel to the fracture plane(Scheme 2)and σ_(2) cutting through the fracture plane(Scheme 3),under varying σ_(3) from 10 MPa to 40 MPa.The peak or fracture reactivation strength,deformation,failure mode,and post-peak mechanical behavior of intact(Scheme 1)and pre-fractured(Schemes 2 and 3)specimens were also compared.Results show that for intact specimens,the stress remains nearly constant in the residual sliding stage with no stick-slip,and the newly formed fracture surface only propagates along the σ_(2) direction when σ_(3) ranges from 10 MPa to 30 MPa,while it extends along both σ_(2) and σ_(3) directions when σ_(3) increases to 40 MPa;for the pre-fractured specimens,the fractures are usually reactivated under all the σ_(3) levels in Scheme 2,but fracture reactivation only occurs when σ_(3) is greater than 25 MPa in Scheme 3,below which new faulting traversing the original macro fracture occurs.In all the test schemes,both ε_(2) and ε_(3) experience an accumulative process of elongation,after which an abrupt change occurs at the point of the final failure;the degree of this change is dependent on the orientation of the new faulting or the slip direction of the original fracture,and it is generally more than 10 times larger in the slip direction of the original fracture than in the non-slip direction.Besides,the differential stress(peak stress)required for reactivation and the post-peak stress drop increase with increasing σ_(3).Post-peak stress drop and residual strength in Scheme 3 are generally greater than those in Scheme 2 at the same σ_(3) value.Our study clearly shows that intermediate principal stress orientation not only affects the fracture reactivation strength but also influences the slip deformation and failure modes.These new findings facilitate the mitigation of dynamic geological hazards associated with fracture and fault slip.
基金supported by Princess Nourah bint Abdulrahman University Researchers Supporting Project Number(PNURSP2025R317),Princess Nourah bintAbdulrahman University,Riyadh,Saudi Arabia.
文摘Aspergillus species produce aflatoxins and raise concerns about food safety in departmental stores and manufacturing mills.To address the risks posed by aflatoxins,and to advise the public on the highest quality rice that serves as a nutritious food source,an inquiry following the guidelines outlined in both local and international standards of food safety for the presence of aflatoxins is an essential requirement.Therefore,16 white rice samples were selected randomly from low/high socio-economic departmental stores from 16 different localities.Grind powdered rice filtrate was extracted using chloroform.The filtrate applied on TLC plates and the amount of aflatoxin and moisture contents were determined.In the non-infected rice,moisture content was low(9.08%)whereas high[13.65%>12%(standard>value)]in infected ones.Four out of 8 samples of low-quality rice were contaminated with AFB_(1) and AFB_(2)(ranging from 22.2 to 29.3μg/kg).All the samples except one(22.3μg/kg)from high-quality rice were certified fit despite the contamination with AFB_(1).Furthermore,phylogenetic analysis showed Aspergillus flavus from unfit low(Long grain brown and Brown basmati)and high-quality(Basmati-198)rice whereas A.parasiticus from unfit low-quality Medium-grain brown rice.The presented research proves that the detection of fungi and aflatoxins in rice grains poses a huge risk to the health of consumers.Therefore,it is necessary to check the rice grains before distribution.
基金Supported by Project of NMPA Key Laboratory for Quality Control of Traditional Chinese Medicine(2023GSMPA-KL06,2024GSMPA-KL16).
文摘[Objectives]To investigate the content and distribution of inorganic elements in Astragalus membranaceus sourced from various regions in Gansu Province.[Methods]28 batches of A.membranaceus samples were collected and subsequently digested using the Multiwave 7000 super microwave digestion system.The contents of aluminum(Al),barium(Ba),beryllium(Be),cobalt(Co),chromium(Cr),iron(Fe),gallium(Ga),magnesium(Mg),manganese(Mn),nickel(Ni),antimony(Sb),tin(Sn),strontium(Sr),titanium(Ti),thallium(Tl),vanadium(V),and zinc(Zn)were quantified utilizing a PerkinElmer 2000 inductively coupled plasma mass spectrometer.Principal component analysis was performed utilizing SPSS 25.0 to identify the distinctive characteristic elements of A.membranaceus.Additionally,systematic cluster analysis was conducted using these characteristic elements as variables to investigate the relationship between the primary inorganic elements and the geographical origin of A.membranaceus.[Results]17 inorganic elements were identified in A.membranaceus specimens collected from Gansu Province,with characteristic elements including Ba,Co,Fe,Ga,Mn,Zn,and Sn.The contents of inorganic elements in various sources of A.membranaceus exhibited significant variability and demonstrated distinct clustering characteristics.[Conclusions]A.membranaceus,originating from Gansu Province,exhibits a high content of inorganic elements.However,variations in ecological environments can lead to differences in the specific inorganic elements that are enriched.This study aims to provide a reference for the further development and application of A.membranaceus.
基金supported by the Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments,China(Grant No.22dz2260800)the Shanghai Science and Technology Committee,China(Grant No.22JC1410300).
文摘Multiple principal element alloys(MPEAs),also known as high-entropy alloys,have attracted significant attention because of their exceptional mechanical and thermal properties.A critical factor influencing these properties is suggested to be the presence of chemical short-range order(SRO),characterized by specific atomic arrangements occurring more frequently than in a random distribution.Despite extensive efforts to elucidate SRO,particularly in face-centered cubic(fcc)3d transition metal-based MPEAs,several key aspects remain under debate:the conditions under which SRO forms,the reliability of characterization methods for detecting SRO,and its quantitative impact on mechanical performance.This review summarizes the challenges and unresolved issues in this emerging field,drawing comparisons with well-established research on SRO in binary alloys over the past few decades.Through this cross-system comparison,we aim to provide new insights into SRO from a comprehensive perspective.
文摘This paper explores the relationship between leader values and actions in the Chinese context.The Chinese Value Instrument(CVI)and the Strategic Leadership Questionnaire(SLQ)were used as the primary data collection tools.The CVI was used to measure the presence of ten values:(1)social harmony,(2)benevolence and honesty,(3)initiative and innovation(challenge and creativity),(4)achievement and power,(5)zhongyong(practicality and modesty),(6)stability,(7)familial loyalty,(8)happiness,(9)renqing(sympathy)and guanxi(personal relationships),and(10)freedom and equity.The findings indicate that achievement and initiative were at the low end of the value continuum.Familial loyalty,social harmony,and benevolence were at the high end of the value continuum.The SLQ measured the managing,transforming,bonding,bridging,and bartering actions leaders use to mobilize and gain support from followers.The findings indicate that the Chinese school principal management prototype is formed around transforming and bonding actions.This prototype changes depending on role assignment and school type.A connection between leader values and actions was established with regard to the values of achievement and power,benevolence and honesty,and stability.
文摘This paper reviews the history and lessons of global oil crises while exploring the establishment of a quantitative evaluation model for oil security with Chinese characteristics.Using principal component analysis,it constructs an oil security evaluation indicator system for China with two main-level indicators:foreign oil dependency and its impacts,and market intervention and security assurance.
基金The National Key R&D Program of China,No.2023YFC3008300The Second Tibetan Plateau Scientific Expedition and Research(STEP),No.2019QZKK0903+1 种基金The Science and Technology Research Program of Institute of Mountain Hazards and Environment,CAS,No.IMHE-ZDRW-03National Natural Science Foundation of China,No.42071017。
文摘Damming is a major geomorphological event characterized by catastrophic consequences and profound impacts on fluvial landscape evolution.Extensive Quaternary detrital deposits(DD)have been discovered in the Daju Basin.Some research suggests that these deposits are potentially associated with Great Flood events in the mainstream region.However,considering the multiplicity and complexity of the deposition,they may also result from catastrophic debris flows in local gullies.Consequently,we conducted a comprehensive investigation of detrital deposits and collected 64 provenance samples.The sediment provenance was analyzed by grain size distribution and elemental composition characterization.The results are as follows:(1)The detrital deposits in the basin are predominantly composed of sand and gravel,with some clay.(2)The results of the elemental ratios and multivariate statistical analysis confirmed the similarity in material composition between the detrital deposits in the basin and those from the Muduoluo Gully.(3)The discovery of palaeolandslides and lacustrine deposits in the study area indicates the existence of ancient dammed lakes and historical river damming events.The detrital deposits likely represent fan delta sediments formed by water-land interactions caused by damming events.Our study highlights new insights into discriminating the provenances of detrital deposits in localized regions,providing a new perspective for investigating geological hazards in the Jinsha River Basin.
基金supported by the Natural Science Foundation of China(Grant Nos.42374032,42174103,42004073)Provincial Natural Science Foundation(2024JJ8348)the Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region,Ministry of Natural Resources(NRMSSHR2023Y01)。
文摘The Global Navigation Satellite System(GNSS)is vital for monitoring terrestrial water storage(TWS).However,effectively extracting hydrological load deformation from GNSS observations poses a significant challenge.This study proposes a novel strategy;the seasonal hydrological load signals are removed from the raw data,and the remaining signals use principal component analysis(PCA).Simulation results from Yunnan Province demonstrate that the spatial distribution of the root mean square error(RMSE)is improved by approximately 15% compared with traditional PCA extraction from raw data.From January 2013 to December 2022,TWS was inverted from 24 GNSS stations in Yunnan Province.The spatial distribution and time series of TWS inverted from GNSS align well with those TWS inferred from the Gravity Recovery and Climate Experiment(GRACE),GRACE Follow-On(GFO),and the Global Land Data Assimilation System(GLDAS)land surface model.However,the amplitude of the GNSS-inverted TWS is slightly higher.Since GNSS ground stations are more sensitive to hydrological load signals,they show correlations with precipitation data that are 8.6%and 6.0%higher than those of GRACE and GLDAS,respectively.In the power spectral density analysis of GRACE/GFO,GLDAS,and GNSS,the signal strength of GNSS is much higher than that of GRACE/GFO and GLDAS in the June and February cycles.These findings suggest that the new data extraction strategy can capture higher frequency hydrological signals in TWS,and GNSS observations can help address limitations in GRACE/GFO observations.This study demonstrates the potential of GNSS TWS in capturing higher-frequency hydrological signals and climate extremes application.
文摘Purpose:This study analyzes the profiles of elite Brazilian researchers,recognized through the prestigious CNPq productivity scholarships.By identifying distinct researcher clusters,the study sheds light on different academic strategies,levels of productivity,and academic contributions within the Brazilian higher education system.Design/methodology/approach:The research analyzes a comprehensive dataset of 14,003 researchers,employing principal component analysis(PCA)followed by cluster analysis to group researchers based on their academic attributes.The clusters reflect diverse aspects of research productivity,graduate supervisions,and publication patterns.Findings:The analysis reveals the existence of three distinct researcher profiles(the Advanced Supervisors,the Book Publishers/Organizers,and the Generalists).The study also highlights the characteristics of highcaliber scientists,representing the upper echelon of Brazilian researchers in terms of productivity and impact.Research limitations:Although the study provides a robust analysis of the Brazilian system,the results reflect specific characteristics of the Brazilian academic context.Furthermore,the analysis was restricted to normalized annual data,which may overlook temporal variations in researcher productivity.Pratical implications:The findings provide valuable insights for policy makers,funding agencies(such as CNPq),and university administrators who aim to develop tailored support programs for different researcher profiles.Originality/value:The cluster-based profiling offers a novel perspective on how different academic trajectories coexist within a national science system,offering lessons for other emerging economies.
文摘The basement aquifers in Burkina Faso are increasingly exposed to groundwater pollution,largely due to socio-economic activities and climatic fluctuations,particularly the reduction in rainfall.This pollution makes the management and understanding of these aquifers particularly complex.To elucidate the processes controlling this contamination,a methodological approach combining principal component analysis(PCA)and multivariate statistical techniques was adopted.The study analyzed sixteen physicochemical parameters from 58 water samples.The primary objective of this research is to assess groundwater quality and deepen the understanding of the key factors influencing the spatial variation of their chemical composition.The results obtained will contribute to better planning of preservation and sustainable management measures for water resources in Burkina Faso.The results show that three principal components explain 72%of the variance,identifying anthropogenic inputs,with two components affected by mineralization and one by pollution.The study reveals that the groundwater is aggressive and highly corrosive,with calcite saturation.Water-rock interactions appear to be the main mechanisms controlling the hydrochemistry of groundwater,with increasing concentrations of cations and anions as the water travels through percolation pathways.PCA also revealed that the residence time of the water and leaching due to human activities significantly influence water quality,primarily through mineralization processes.These results suggest that rock weathering,coupled with reduced rainfall,constitutes a major vulnerability for aquifer recharge.
