Existing blockwise empirical likelihood(BEL)method blocks the observations or their analogues,which is proven useful under some dependent data settings.In this paper,we introduce a new BEL(NBEL)method by blocking the ...Existing blockwise empirical likelihood(BEL)method blocks the observations or their analogues,which is proven useful under some dependent data settings.In this paper,we introduce a new BEL(NBEL)method by blocking the scoring functions under high dimensional cases.We study the construction of confidence regions for the parameters in spatial autoregressive models with spatial autoregressive disturbances(SARAR models)with high dimension of parameters by using the NBEL method.It is shown that the NBEL ratio statistics are asymptoticallyχ^(2)-type distributed,which are used to obtain the NBEL based confidence regions for the parameters in SARAR models.A simulation study is conducted to compare the performances of the NBEL and the usual EL methods.展开更多
Weighted exponential distribution W ED(α,λ)with shape parameterαand scale parameterλpossesses some good properties and can be used as a good fit to survival time data compared to other distributions such as gamma,...Weighted exponential distribution W ED(α,λ)with shape parameterαand scale parameterλpossesses some good properties and can be used as a good fit to survival time data compared to other distributions such as gamma,Weibull,or generalized exponential distribution.In this article,we proved the existence and uniqueness of the maximum likelihood estimator(MLE)of the parameters of W ED(α,λ)in simple random sampling(SRS)and provided explicit expressions for the Fisher information number in SRS.Moreover,we also proved the existence and uniqueness of the MLE of the parameters of W ED(α,λ)in ranked set sampling(RSS)and provided explicit expressions for the Fisher information number in RSS.Simulation studies show that these MLEs in RSS can be real competitors for those in SRS.展开更多
Over the past few decades, numerous adaptive Kalman filters(AKFs) have been proposed. However, achieving online estimation with both high estimation accuracy and fast convergence speed is challenging, especially when ...Over the past few decades, numerous adaptive Kalman filters(AKFs) have been proposed. However, achieving online estimation with both high estimation accuracy and fast convergence speed is challenging, especially when both the process noise and measurement noise covariance matrices are relatively inaccurate. Maximum likelihood estimation(MLE) possesses the potential to achieve this goal, since its theoretical accuracy is guaranteed by asymptotic optimality and the convergence speed is fast due to weak dependence on accurate state estimation.Unfortunately, the maximum likelihood cost function is so intricate that the existing MLE methods can only simply ignore all historical measurement information to achieve online estimation,which cannot adequately realize the potential of MLE. In order to design online MLE-based AKFs with high estimation accuracy and fast convergence speed, an online exploratory MLE approach is proposed, based on which a mini-batch coordinate descent noise covariance matrix estimation framework is developed. In this framework, the maximum likelihood cost function is simplified for online estimation with fewer and simpler terms which are selected in a mini-batch and calculated with a backtracking method. This maximum likelihood cost function is sidestepped and solved by exploring possible estimated noise covariance matrices adaptively while the historical measurement information is adequately utilized. Furthermore, four specific algorithms are derived under this framework to meet different practical requirements in terms of convergence speed, estimation accuracy,and calculation load. Abundant simulations and experiments are carried out to verify the validity and superiority of the proposed algorithms as compared with existing state-of-the-art AKFs.展开更多
BACKGROUND Attention deficit hyperactivity disorder(ADHD)is a prevalent neurodevelopmental disorder in adolescents characterized by inattention,hyperactivity,and impulsivity,which impact cognitive,behavioral,and emoti...BACKGROUND Attention deficit hyperactivity disorder(ADHD)is a prevalent neurodevelopmental disorder in adolescents characterized by inattention,hyperactivity,and impulsivity,which impact cognitive,behavioral,and emotional functioning.Resting-state functional magnetic resonance imaging(rs-fMRI)provides critical insights into the functional architecture of the brain in ADHD.Despite extensive research,specific brain regions consistently affected in ADHD patients during these formative years have not been comprehensively delineated.AIM To identify consistent vulnerable brain regions in adolescent ADHD patients using rs-fMRI and activation likelihood estimation(ALE)meta-analysis.METHODS We conducted a comprehensive literature search up to August 31,2024,to identify studies investigating functional brain alterations in adolescents with ADHD.We utilized regional homogeneity(ReHo),amplitude of low-frequency fluctuations(ALFF),dynamic ALFF(dALFF)and fractional ALFF(fALFF)analyses.We compared the regions of aberrant spontaneous neural activity in adolescents with ADHD with those in healthy controls(HCs)using ALE.RESULTS Fifteen studies(468 adolescent ADHD patients and 466 HCs)were included.Combining the ReHo and ALFF/fALFF/dALFF data,the results revealed increased activity in the right lingual gyrus[LING,Brodmann Area(BA)18],left LING(BA 18),and right cuneus(CUN,BA 23)in adolescent ADHD patients compared with HCs(voxel size:592-32 mm³,P<0.05).Decreased activity was observed in the left medial frontal gyrus(MFG,BA 9)and left precuneus(PCUN,BA 31)in adolescent ADHD patients compared with HCs(voxel size:960-456 mm³,P<0.05).Jackknife sensitivity analyses demonstrated robust reproducibility in 11 of the 13 tests for the right LING,left LING,and right CUN and in 11 of the 14 tests for the left MFG and left PCUN.CONCLUSION We identified specific brain regions with both increased and decreased activity in adolescent ADHD patients,enhancing our understanding of the neural alterations that occur during this pivotal stage of development.展开更多
In order to obtain the life information of the vacuum fluorescent display （VFD） in a short time, a model of constant stress accelerated life tests （CSALT） is established with its filament temperature increased, an...In order to obtain the life information of the vacuum fluorescent display （VFD） in a short time, a model of constant stress accelerated life tests （CSALT） is established with its filament temperature increased, and four constant stress tests are conducted. The Weibull function is applied to describe the life distribution of the VFD, and the maximum likelihood estimation （MLE） and its iterative flow chart are used to calculate the shape parameters and the scale parameters. Furthermore, the accelerated life equation is determined by the least square method, the Kolmogorov-Smirnov test is performed to verify whether the VFD life meets the Weibull distribution or not, and selfdeveloped software is employed to predict the average life and the reliable life. Statistical data analysis results demonstrate that the test plans are feasible and versatile, that the VFD life follows the Weibull distribution, and that the VFD accelerated model satisfies the linear Arrhenius equation. The proposed method and the estimated life information of the VFD can provide some significant guideline to its manufacturers and customers.展开更多
目的探讨应用静息态功能磁共振研究耳鸣患者较为一致的活动异常脑区,从而揭示耳鸣患者脑损伤及功能重塑的神经机制。方法检索1999年1月1日至2023年10月12日采用局部一致性(regional honogeneity,ReHo)及低频振幅(amplitude of low-frequ...目的探讨应用静息态功能磁共振研究耳鸣患者较为一致的活动异常脑区,从而揭示耳鸣患者脑损伤及功能重塑的神经机制。方法检索1999年1月1日至2023年10月12日采用局部一致性(regional honogeneity,ReHo)及低频振幅(amplitude of low-frequency fluctuation,ALFF)、分数低频振幅指标评估耳鸣患者脑功能改变的文献,按照严格的纳排标准,采用激活似然估计法对既往研究中耳鸣患者相对于健康对照组自发脑神经活动异常的脑区进行整合分析。结果共纳入22篇29个研究(耳鸣患者746例,健康对照组653例),联合ALFF、分数低频振幅与ReHo数据Meta分析结果显示,耳鸣患者相对于健康对照组,右颞中回活动增加,并未发现活动减低的脑区;单独ReHo数据分析结果显示,左侧枕中回、左侧后扣带回活动增加;右背外侧额上回、左侧小脑前叶活动减少;单独ALFF数据分析结果显示,耳鸣患者相对于健康对照组未出现任何活动增高或减低的脑区(体素大小≥200 mm^(3),FDR P<0.05)。结论运用激活似然估计法-Meta分析方法证实耳鸣患者多个脑区存在自发活动异常,有助于揭示耳鸣脑功能损伤及重塑的神经病理学基础。展开更多
An improved Gaussian mixture model （GMM）- based clustering method is proposed for the difficult case where the true distribution of data is against the assumed GMM. First, an improved model selection criterion, the ...An improved Gaussian mixture model （GMM）- based clustering method is proposed for the difficult case where the true distribution of data is against the assumed GMM. First, an improved model selection criterion, the completed likelihood minimum message length criterion, is derived. It can measure both the goodness-of-fit of the candidate GMM to the data and the goodness-of-partition of the data. Secondly, by utilizing the proposed criterion as the clustering objective function, an improved expectation- maximization （EM） algorithm is developed, which can avoid poor local optimal solutions compared to the standard EM algorithm for estimating the model parameters. The experimental results demonstrate that the proposed method can rectify the over-fitting tendency of representative GMM-based clustering approaches and can robustly provide more accurate clustering results.展开更多
In this paper,the empirical likelihood confidence regions for the regression coefficient in a linear model are constructed under m-dependent errors.It is shown that the blockwise empirical likelihood is a good way to ...In this paper,the empirical likelihood confidence regions for the regression coefficient in a linear model are constructed under m-dependent errors.It is shown that the blockwise empirical likelihood is a good way to deal with dependent samples.展开更多
目的探索幻想性视错觉是否存在于特发性快速眼动睡眠期行为障碍(idiopathic rapid eye movement sleep behavior disorder,iRBD)患者中并分析相关风险因素以及与前驱期帕金森病(Parkinson′s disease,PD)风险的关系。方法本研究采用横...目的探索幻想性视错觉是否存在于特发性快速眼动睡眠期行为障碍(idiopathic rapid eye movement sleep behavior disorder,iRBD)患者中并分析相关风险因素以及与前驱期帕金森病(Parkinson′s disease,PD)风险的关系。方法本研究采用横断面研究设计,于2023年3月至2024年12月在广州社区招募53名健康对照者(对照组)以及在广州医科大学附属脑科医院纳入78名iRBD患者(iRBD组)和30例帕金森病患者(PD组)。所有受试者均完成幻想性视错觉测试,并采用统一帕金森病评定量表第三部分、蒙特利尔认知评估量表与连线测试、帕金森病自主神经症状量表、嗅棒测试及9项患者健康问卷和7项广泛性焦虑量表等评估运动、认知、自主神经、嗅觉功能和抑郁或焦虑症状等。3组人口统计学和一般资料比较采用方差分析或Kruskal-Wallis检验。采用广义线性模型分析3组间临床特征以及帕金森病前驱期相关风险得分的差异,在iRBD患者中根据是否存在幻想性视错觉进行亚组比较分析。采用接收者操作特征曲线分析幻想性视错觉等指标对iRBD的鉴别效能。结果iRBD组和PD组幻想性视错觉症状均显著多于对照组[(0.9±0.2)、(1.2±0.3)、(0.2±0.2)个,Waldχ^(2)=9.24,P=0.010],但iRBD组与PD组之间差异无统计学意义。相比无幻想性视错觉的iRBD患者,有幻想性视错觉的iRBD患者年龄更大[(62.4±1.1)岁与(67.2±1.4)岁,Waldχ^(2)=7.26,P=0.007]、连线测试-B时间更长[(72.1±6.3)s与(99.0±8.4)s,Waldχ^(2)=6.33,P=0.012]和嗅棒测试阈值得分更低[(5.1±0.4)分与(3.6±0.6)分,Waldχ^(2)=4.30,P=0.038],而前驱期帕金森病风险得分组间差异无统计学意义。幻想性视错觉对iRBD诊断效能有限,曲线下面积(area under the curve,AUC)=0.64,在整合蒙特利尔认知评估量表的前部脑区得分、连线测试-B和嗅棒测试得分后,其诊断效能显著提高(AUC=0.83)。结论iRBD患者已表现出幻想性视错觉增多,但其与前驱期帕金森病风险得分无显著关联,其对疾病进展的预测价值需前瞻性研究进一步证实。展开更多
基金Supported by the National Natural Science Foundation of China(12061017,12361055)the Research Fund of Guangxi Key Lab of Multi-source Information Mining&Security(22-A-01-01)。
文摘Existing blockwise empirical likelihood(BEL)method blocks the observations or their analogues,which is proven useful under some dependent data settings.In this paper,we introduce a new BEL(NBEL)method by blocking the scoring functions under high dimensional cases.We study the construction of confidence regions for the parameters in spatial autoregressive models with spatial autoregressive disturbances(SARAR models)with high dimension of parameters by using the NBEL method.It is shown that the NBEL ratio statistics are asymptoticallyχ^(2)-type distributed,which are used to obtain the NBEL based confidence regions for the parameters in SARAR models.A simulation study is conducted to compare the performances of the NBEL and the usual EL methods.
基金Supported by the National Science Foundation of China(11901236,12261036)Scientific Research Fund of Hunan Provincial Education Department(21A0328)+2 种基金Provincial Natural Science Foundation of Hunan(2022JJ30469)Young Core Teacher Foundation of Hunan Province([2020]43)Provincial Postgraduate Innovation Foundation of Hunan(CX20221113)。
文摘Weighted exponential distribution W ED(α,λ)with shape parameterαand scale parameterλpossesses some good properties and can be used as a good fit to survival time data compared to other distributions such as gamma,Weibull,or generalized exponential distribution.In this article,we proved the existence and uniqueness of the maximum likelihood estimator(MLE)of the parameters of W ED(α,λ)in simple random sampling(SRS)and provided explicit expressions for the Fisher information number in SRS.Moreover,we also proved the existence and uniqueness of the MLE of the parameters of W ED(α,λ)in ranked set sampling(RSS)and provided explicit expressions for the Fisher information number in RSS.Simulation studies show that these MLEs in RSS can be real competitors for those in SRS.
基金supported in part by the National Key Research and Development Program of China(2023YFB3906403)the National Natural Science Foundation of China(62373118,62173105)the Natural Science Foundation of Heilongjiang Province of China(ZD2023F002)
文摘Over the past few decades, numerous adaptive Kalman filters(AKFs) have been proposed. However, achieving online estimation with both high estimation accuracy and fast convergence speed is challenging, especially when both the process noise and measurement noise covariance matrices are relatively inaccurate. Maximum likelihood estimation(MLE) possesses the potential to achieve this goal, since its theoretical accuracy is guaranteed by asymptotic optimality and the convergence speed is fast due to weak dependence on accurate state estimation.Unfortunately, the maximum likelihood cost function is so intricate that the existing MLE methods can only simply ignore all historical measurement information to achieve online estimation,which cannot adequately realize the potential of MLE. In order to design online MLE-based AKFs with high estimation accuracy and fast convergence speed, an online exploratory MLE approach is proposed, based on which a mini-batch coordinate descent noise covariance matrix estimation framework is developed. In this framework, the maximum likelihood cost function is simplified for online estimation with fewer and simpler terms which are selected in a mini-batch and calculated with a backtracking method. This maximum likelihood cost function is sidestepped and solved by exploring possible estimated noise covariance matrices adaptively while the historical measurement information is adequately utilized. Furthermore, four specific algorithms are derived under this framework to meet different practical requirements in terms of convergence speed, estimation accuracy,and calculation load. Abundant simulations and experiments are carried out to verify the validity and superiority of the proposed algorithms as compared with existing state-of-the-art AKFs.
基金Supported by National Natural Science Foundation of China,No.82460282Guizhou Province Science and Technology Plan Project,No.ZK-2023-195+1 种基金Guizhou High-Level Innovative Talent Project,No.gzwjrs2022-013Health Commission of Guizhou Province Project,No.gzwkj2024-475 and No.gzwkj2021-150.
文摘BACKGROUND Attention deficit hyperactivity disorder(ADHD)is a prevalent neurodevelopmental disorder in adolescents characterized by inattention,hyperactivity,and impulsivity,which impact cognitive,behavioral,and emotional functioning.Resting-state functional magnetic resonance imaging(rs-fMRI)provides critical insights into the functional architecture of the brain in ADHD.Despite extensive research,specific brain regions consistently affected in ADHD patients during these formative years have not been comprehensively delineated.AIM To identify consistent vulnerable brain regions in adolescent ADHD patients using rs-fMRI and activation likelihood estimation(ALE)meta-analysis.METHODS We conducted a comprehensive literature search up to August 31,2024,to identify studies investigating functional brain alterations in adolescents with ADHD.We utilized regional homogeneity(ReHo),amplitude of low-frequency fluctuations(ALFF),dynamic ALFF(dALFF)and fractional ALFF(fALFF)analyses.We compared the regions of aberrant spontaneous neural activity in adolescents with ADHD with those in healthy controls(HCs)using ALE.RESULTS Fifteen studies(468 adolescent ADHD patients and 466 HCs)were included.Combining the ReHo and ALFF/fALFF/dALFF data,the results revealed increased activity in the right lingual gyrus[LING,Brodmann Area(BA)18],left LING(BA 18),and right cuneus(CUN,BA 23)in adolescent ADHD patients compared with HCs(voxel size:592-32 mm³,P<0.05).Decreased activity was observed in the left medial frontal gyrus(MFG,BA 9)and left precuneus(PCUN,BA 31)in adolescent ADHD patients compared with HCs(voxel size:960-456 mm³,P<0.05).Jackknife sensitivity analyses demonstrated robust reproducibility in 11 of the 13 tests for the right LING,left LING,and right CUN and in 11 of the 14 tests for the left MFG and left PCUN.CONCLUSION We identified specific brain regions with both increased and decreased activity in adolescent ADHD patients,enhancing our understanding of the neural alterations that occur during this pivotal stage of development.
基金Undergraduate Education High land Construction Project of Shanghaithe Key Course Construction of Shanghai Education Committee (No.20075302)the Key Technology R&D Program of Shanghai Municipality (No.08160510600)
文摘In order to obtain the life information of the vacuum fluorescent display （VFD） in a short time, a model of constant stress accelerated life tests （CSALT） is established with its filament temperature increased, and four constant stress tests are conducted. The Weibull function is applied to describe the life distribution of the VFD, and the maximum likelihood estimation （MLE） and its iterative flow chart are used to calculate the shape parameters and the scale parameters. Furthermore, the accelerated life equation is determined by the least square method, the Kolmogorov-Smirnov test is performed to verify whether the VFD life meets the Weibull distribution or not, and selfdeveloped software is employed to predict the average life and the reliable life. Statistical data analysis results demonstrate that the test plans are feasible and versatile, that the VFD life follows the Weibull distribution, and that the VFD accelerated model satisfies the linear Arrhenius equation. The proposed method and the estimated life information of the VFD can provide some significant guideline to its manufacturers and customers.
基金The National Natural Science Foundation of China(No.61105048,60972165)the Doctoral Fund of Ministry of Education of China(No.20110092120034)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK2010240)the Technology Foundation for Selected Overseas Chinese Scholar,Ministry of Human Resources and Social Security of China(No.6722000008)the Open Fund of Jiangsu Province Key Laboratory for Remote Measuring and Control(No.YCCK201005)
文摘An improved Gaussian mixture model （GMM）- based clustering method is proposed for the difficult case where the true distribution of data is against the assumed GMM. First, an improved model selection criterion, the completed likelihood minimum message length criterion, is derived. It can measure both the goodness-of-fit of the candidate GMM to the data and the goodness-of-partition of the data. Secondly, by utilizing the proposed criterion as the clustering objective function, an improved expectation- maximization （EM） algorithm is developed, which can avoid poor local optimal solutions compared to the standard EM algorithm for estimating the model parameters. The experimental results demonstrate that the proposed method can rectify the over-fitting tendency of representative GMM-based clustering approaches and can robustly provide more accurate clustering results.
文摘In this paper,the empirical likelihood confidence regions for the regression coefficient in a linear model are constructed under m-dependent errors.It is shown that the blockwise empirical likelihood is a good way to deal with dependent samples.
文摘目的探索幻想性视错觉是否存在于特发性快速眼动睡眠期行为障碍(idiopathic rapid eye movement sleep behavior disorder,iRBD)患者中并分析相关风险因素以及与前驱期帕金森病(Parkinson′s disease,PD)风险的关系。方法本研究采用横断面研究设计,于2023年3月至2024年12月在广州社区招募53名健康对照者(对照组)以及在广州医科大学附属脑科医院纳入78名iRBD患者(iRBD组)和30例帕金森病患者(PD组)。所有受试者均完成幻想性视错觉测试,并采用统一帕金森病评定量表第三部分、蒙特利尔认知评估量表与连线测试、帕金森病自主神经症状量表、嗅棒测试及9项患者健康问卷和7项广泛性焦虑量表等评估运动、认知、自主神经、嗅觉功能和抑郁或焦虑症状等。3组人口统计学和一般资料比较采用方差分析或Kruskal-Wallis检验。采用广义线性模型分析3组间临床特征以及帕金森病前驱期相关风险得分的差异,在iRBD患者中根据是否存在幻想性视错觉进行亚组比较分析。采用接收者操作特征曲线分析幻想性视错觉等指标对iRBD的鉴别效能。结果iRBD组和PD组幻想性视错觉症状均显著多于对照组[(0.9±0.2)、(1.2±0.3)、(0.2±0.2)个,Waldχ^(2)=9.24,P=0.010],但iRBD组与PD组之间差异无统计学意义。相比无幻想性视错觉的iRBD患者,有幻想性视错觉的iRBD患者年龄更大[(62.4±1.1)岁与(67.2±1.4)岁,Waldχ^(2)=7.26,P=0.007]、连线测试-B时间更长[(72.1±6.3)s与(99.0±8.4)s,Waldχ^(2)=6.33,P=0.012]和嗅棒测试阈值得分更低[(5.1±0.4)分与(3.6±0.6)分,Waldχ^(2)=4.30,P=0.038],而前驱期帕金森病风险得分组间差异无统计学意义。幻想性视错觉对iRBD诊断效能有限,曲线下面积(area under the curve,AUC)=0.64,在整合蒙特利尔认知评估量表的前部脑区得分、连线测试-B和嗅棒测试得分后,其诊断效能显著提高(AUC=0.83)。结论iRBD患者已表现出幻想性视错觉增多,但其与前驱期帕金森病风险得分无显著关联,其对疾病进展的预测价值需前瞻性研究进一步证实。
文摘研究伴自杀意念(suicidal ideation,SI)的抑郁症患者、不伴自杀意念(no suicidal ideation,NSI)的抑郁症患者、健康对照(healthy controls,HC)的静息态功能性核磁共振(resting-state functional magnetic resonance imaging,rs-fMRI)低频振幅(amplitude of low frequency fluctuations,ALFF)的活动差异,通过对患者rs-fMRI的脑功能进行Meta分析。在Pubmed、Embase、Web of Science、Cochrane Library、中国知网、万方数据库中搜索关于伴SI的抑郁患者rs-fMRI的相关文献。依据系统评价的方法,对纳入文献进行筛选、质量评价、提取特征、激活似然估计法(activation likelihood estimation,ALE)Meta分析,汇总了既往文献的SI抑郁症患者、NSI抑郁症患者与HC之间的ALFF的收敛脑区。共纳入6篇文献,提取SI组患者175例,NSI组患者137例,HC组125名,其中SI组和NSI组之间的差异脑区共有18个。将差异脑区纳入ALE Meta分析,结果显示:SI组相较于NSI组ALFF增高的脑区有左侧枕叶舌回(ALE=1.859×10^(-2),P<0.01,Z=5.688)、右侧枕中回(ALE=1.823×10^(-2),P<0.01,Z=5.562)。左侧枕叶舌回及右侧枕中回异常激活与抑郁症患者的自杀意念可能相关。
