89 research outputs found

    Simulation-Based Hypothesis Testing of High Dimensional Means Under Covariance Heterogeneity

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    In this paper, we study the problem of testing the mean vectors of high dimensional data in both one-sample and two-sample cases. The proposed testing procedures employ maximum-type statistics and the parametric bootstrap techniques to compute the critical values. Different from the existing tests that heavily rely on the structural conditions on the unknown covariance matrices, the proposed tests allow general covariance structures of the data and therefore enjoy wide scope of applicability in practice. To enhance powers of the tests against sparse alternatives, we further propose two-step procedures with a preliminary feature screening step. Theoretical properties of the proposed tests are investigated. Through extensive numerical experiments on synthetic datasets and an human acute lymphoblastic leukemia gene expression dataset, we illustrate the performance of the new tests and how they may provide assistance on detecting disease-associated gene-sets. The proposed methods have been implemented in an R-package HDtest and are available on CRAN.Comment: 34 pages, 10 figures; Accepted for biometric

    Recurrence of odontogenic keratocysts and possible prognostic factors : review of 455 patients

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    To describe epidemiological features of 565 Chinese patients with odontogenic keratocysts (OKC), to investigate possible prognostic factors related to recurrence, and to analyse features of recurrent OKC (rOKC). A retrospective chart review of 565 cases of OKC treated between 2003 and 2015 was undertaken. The probability of recurrence related to prognostic factors including large size, cortical perforation combined with involved teeth in the lumen of the cyst, inflammation, sites of the involved lesion, sex, and daughter cyst variables were analysed. The subsequent relapse of each OKC was compared. Patients ranged in age from 7 to 81 years (mean age, 28.4 years) and, of those affected, 66.9% were male and 33.1% were female. Mandibular OKC occurred in 63.01% and 36.99% occurred in the maxilla, 80.53% of patients had non-rOKC, 10.44% rOKC, and 9.03% had multiple OKC lesions. Enucleation with preservation of the involved teeth in the cystic lesion combined with cortical perforation was statistically associated with high recurrence rate, as were daughter cysts, and multilocular lesions. The number of recurrences and the average time (in years) to relapse decreased from the first relapse of OKC to the third relapse, and the difference was significant (P<.05). Preservation of the involved teeth combined with cortical perforation appeared to be a potential prognostic factor associated with high recurrence. The follow-up evaluation period for rOKC with ? 2 previous treatments should be shorter than for first-time rOKC. The decreasing average duration (years postoperatively) to relapse was related to the number of rOKCs, timing of relapse, and rOKC type

    Risk factors for the rupture of intracranial aneurysms: a systematic review and meta-analysis

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    PurposeThe study aimed to identify potential risk factors for aneurysm rupture by performing a systematic review and meta-analysis.Materials and methodsWe systematically searched the PubMed, Embase, and Cochrane Library electronic databases for eligible studies from their inception until June 2023.ResultsEighteen studies involving 17,069 patients with unruptured intracranial aneurysm (UIA) and 2,699 aneurysm ruptures were selected for the meta-analysis. Hyperlipidemia [odds ratio (OR): 0.47; 95% confidence interval (CI): 0.39–0.56; p &lt; 0.001] and a family history of subarachnoid hemorrhage (SAH) (OR: 0.81; 95% CI: 0.71–0.91; p = 0.001) were associated with a reduced risk of aneurysm rupture. In contrast, a large-size aneurysm (OR: 4.49; 95% CI: 2.46–8.17; p &lt; 0.001), ACA (OR: 3.34; 95% CI: 1.94–5.76; p &lt; 0.001), MCA (OR: 2.16; 95% CI: 1.73–2.69; p &lt; 0.001), and VABA (OR: 2.20; 95% CI: 1.24–3.91; p = 0.007) were associated with an increased risk of aneurysm rupture. Furthermore, the risk of aneurysm rupture was not affected by age, sex, current smoking, hypertension, diabetes mellitus, a history of SAH, and multiple aneurysms.ConclusionThis study identified the predictors of aneurysm rupture in patients with UIAs, including hyperlipidemia, a family history of SAH, a large-size aneurysm, ACA, MCA, and VABA; patients at high risk for aneurysm rupture should be carefully monitored.Systematic Review RegistrationOur study was registered in the INPLASY platform (INPLASY202360062)

    Authenticity identification method for calligraphy regular script based on improved YOLOv7 algorithm

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    A regular calligraphy script of each calligrapher has unique strokes, and a script’s authenticity can be identified by comparing them. Hence, this study introduces a method for identifying the authenticity of regular script calligraphy works based on the improved YOLOv7 algorithm. The proposed method evaluates the authenticity of calligraphy works by detecting and comparing the number of single-character features in each regular script calligraphy work. Specifically, first, we collected regular script calligraphy works from a well-known domestic calligrapher and divided each work into a single-character dataset. Then, we introduced the PConv module in FasterNet, the DyHead dynamic detection header network, and the MPDiou bounding box loss function to optimize the accuracy of the YOLOv7 algorithm. Thus, we constructed an improved algorithm named YOLOv7-PDM, which is used for regular script calligraphy identification. The proposed YOLOv7-PDM model was trained and tested using a prepared regular script single-character dataset. Through experimental results, we confirmed the practicality and feasibility of the proposed method and demonstrated that the YOLOv7-PDM algorithm model achieves 94.19% accuracy (mAP50) in detecting regular script font features, with a single-image detection time of 3.1 m and 31.67M parameters. The improved YOLOv7 algorithm model offers greater advantages in detection speed, accuracy, and model complexity compared to current mainstream detection algorithms. This demonstrates that the developed approach effectively extracts stroke features of regular script calligraphy and provides guidance for future studies on authenticity identification

    East Asian Study of Tropospheric Aerosols and their Impact on Regional Clouds, Precipitation, and Climate (EAST-AIR_(CPC))

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    Aerosols have significant and complex impacts on regional climate in East Asia. Cloud‐aerosol‐precipitation interactions (CAPI) remain most challenging in climate studies. The quantitative understanding of CAPI requires good knowledge of aerosols, ranging from their formation, composition, transport, and their radiative, hygroscopic, and microphysical properties. A comprehensive review is presented here centered on the CAPI based chiefly, but not limited to, publications in the special section named EAST‐AIRcpc concerning (1) observations of aerosol loading and properties, (2) relationships between aerosols and meteorological variables affecting CAPI, (3) mechanisms behind CAPI, and (4) quantification of CAPI and their impact on climate. Heavy aerosol loading in East Asia has significant radiative effects by reducing surface radiation, increasing the air temperature, and lowering the boundary layer height. A key factor is aerosol absorption, which is particularly strong in central China. This absorption can have a wide range of impacts such as creating an imbalance of aerosol radiative forcing at the top and bottom of the atmosphere, leading to inconsistent retrievals of cloud variables from space‐borne and ground‐based instruments. Aerosol radiative forcing can delay or suppress the initiation and development of convective clouds whose microphysics can be further altered by the microphysical effect of aerosols. For the same cloud thickness, the likelihood of precipitation is influenced by aerosols: suppressing light rain and enhancing heavy rain, delaying but intensifying thunderstorms, and reducing the onset of isolated showers in most parts of China. Rainfall has become more inhomogeneous and more extreme in the heavily polluted urban regions

    Atomically thin photoanode of InSe/graphene heterostructure

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    很多物理和化学过程都发生在固体电极与溶液的表界面处,因而表面处离子的吸附、聚集及其在表面的反应都对整个反应过程起到至关重要的作用。然而使用传统的固体电极通常表现出的是体相和表面的复合性质,使得单纯研究电极材料表面效应及表面离子的动力学还存在挑战。二维材料由于其具有单原子层的厚度,晶体中所有原子都处在表面,因而可以作为一种理想的模型体系来仅针对此类表面现象进行研究。课题组选择光电化学池(PEC)分解水反应中的决速步骤氧析出半反应(OER)以作为研究表面离子行为的探针反应。光电极选择同时具有高迁移率、匹配的能级结构以及被抑制的光生电子-空穴复合的单层的二维硒化铟(InSe)材料。并且在手套箱提供的惰性气氛中用单层石墨烯对InSe进行封装,保证了光电极测试条件下长时间的稳定性。该工作揭示了二维异质结表面性质与反应活性的内在联系,希望能为研究电极表面离子效应提供新的材料平台。后续通过选择具有合适表面性能的二维材料,并与传统光电极材料结合,有望发展新型的高性能光阳极材料。 这一研究工作的实验部分是在化学化工学院曹阳教授指导下完成,博士生郑海红、鲁艺珍与广东工业大学轻工化工学院叶凯航博士为论文的共同第一作者。理论计算部分在程俊教授的指导下,由博士生胡晋媛完成。Achieving high-efficiency photoelectrochemical water splitting requires a better understanding of ion kinetics, e.g., diffusion, adsorption and reactions, near the photoelectrode's surface. However, with macroscopic three-dimensional electrodes, it is often difficult to disentangle the contributions of surface effects to the total photocurrent from that of various factors in the bulk. Here, we report a photoanode made from a InSe crystal monolayer that is encapsulated with monolayer graphene to ensure high stability. We choose InSe among other photoresponsive two-dimensional (2D) materials because of its unique properties of high mobility and strongly suppressing electron–hole pair recombination. Using the atomically thin electrodes, we obtained a photocurrent with a density >10 mA cm−2 at 1.23 V versus reversible hydrogen electrode, which is several orders of magnitude greater than other 2D photoelectrodes. In addition to the outstanding characteristics of InSe, we attribute the enhanced photocurrent to the strong coupling between the hydroxide ions and photogenerated holes near the anode surface. As a result, a persistent current even after illumination ceased was also observed due to the presence of ions trapped holes with suppressed electron-hole recombination. Our results provide atomically thin materials as a platform for investigating ion kinetics at the electrode surface and shed light on developing nextgeneration photoelectrodes with high efficiency.The experimental work was supported by the National Key R&D Program of China (2018YFA0306900 and 2018YFA0209500), the National Natural Science Foundation of China (21872114), and China Postdoctoral Science Foundation (2020M682616). 该工作得到了国家重点研究计划(2018YFA0306900、2018YFA0209500),国家自然科学基金(21872114)、中国博士后科学基金(2020M682616)的支持
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