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关键词： 3D raster   distributed GIS   Hadoop Distributed File System   replica placement  

摘要： Geospatial three-dimensional (3D) raster data have been widely used for simple representations and analysis, such as geological models, spatio-temporal satellite data, hyperspectral images, and climate data. With the increasing requirements of resolution and accuracy, the amount of geospatial 3D raster data has grown exponentially. In recent years, the processing of large raster data using Hadoop has gained popularity. However, data uploaded to Hadoop are randomly distributed onto datanodes without consideration of the spatial characteristics. As a result, the direct processing of geospatial 3D raster data produces a massive network data exchange among the datanodes and degrades the performance of the cluster. To address this problem, we propose an efficient group-based replica placement policy for large-scale geospatial 3D raster data, aiming to optimize the locations of the replicas in the cluster to reduce the network overhead. An overlapped group scheme was designed for three replicas of each file. The data in each group were placed in the same datanode, and different colocation patterns for three replicas were implemented to further reduce the communication between groups. The experimental results show that our approach significantly reduces the network overhead during data acquisition for 3D raster data in the Hadoop cluster, and maintains the Hadoop replica placement requirements.

关键词： platinum   pyrrhotite   solid solution   solubility   cooperite   X-ray absorption spectroscopy  

摘要： Pyrrhotite Fe1-xS is the main sulfide component of platinum-group element (PGE) ores and commonly contains from a few tenths to a few dozen ppm of disseminated Pt. Here we report an X-ray absorption spectroscopy investigation into the state of Pt in synthetic pyrrhotite in combination with theoretical spectra modelling. The pyrrhotite crystals were obtained by means of the salt flux technique, using a eutectic mixture of alkali metal halides as the transport media. Analysis of the chemical composition of synthesised crystals showed that an increase of the temperature and sulfur fugacity yields higher concentrations of Pt in pyrrhotite. The Pt content reached 0.6 wt.% at the maximum temperature and sulfur fugacity (t = 720 degrees C, log = -0.1) achieved in a Pt-saturated system. X-ray absorption near-edge structure (XANES) analysis of Pt L-3-edge spectra revealed that Pt is present in pyrrhotite in the 4+ and 2+ 'formal' oxidation states. Theoretical modelling of XANES and interpretation of extended X-ray absorption fine structure (EXAFS) spectra showed that Pt4+ substitutes for Fe in the crystal lattice of pyrrhotite, whereas Pt2+ forms PtS-like clusters disseminated in the pyrrhotite matrix. Atoms of isomorphous Pt4+ are surrounded by 6 S atoms at a distance of 2.39 +/- 0.02 angstrom. According to theoretical simulations using the FDMNES program, the second coordination sphere of the solid-solution Pt contains one vacancy in the Fe sublattice within the Fe-layer. The Pt2+S-like clusters can be considered as a quench product. High sulfur fugacity stabilises the solid-solution Pt and prevents the formation of the PtS-like clusters during cooling. The maximum content of the solid-solution Pt in pyrrhotite is ca. 50 times lower than in pyrite and can be approximated by a straight line in the log C(Pt) vs. 1/T plot, it increases from 1 ppm at 350 degrees C to 3 wt.% at 900 degrees C.

关键词： Early warning of tardiness   Rocket final assembly   Imbalanced learning   Ensemble neural network   Dynamic sampling  

摘要： Establishing an effective early warning mechanism for the rocket final assembly process (RFAP) is crucial for the timely delivery of rockets and the reduction of additional production costs. To solve the unsystematic design of warning indicators and warning levels in RFAP and address the problem of low warning accuracy caused by imbalanced data distribution, this paper redesigns the warning indicators and warning levels in a systematic way, and develops a novel multiclass imbalanced learning method based on dynamic sampling algorithm (DyS) and improved ensemble neural network (IENN). The DyS algorithm dynamically determines the training set after oversampling the minority class, while the IENN can effectively suppress the oscillation in the iterative process of the DyS algorithm and improve the overall classification accuracy by removing the redundant and ineffective networks from the ensemble neural network. The experiment results indicate that the proposed method outperforms other methods in terms of accuracy and stability for early warning of tardiness in RFAP.

关键词： Confidentiality   Patient portals   Adolescent health   Quality improvement  

摘要： Purpose: Managing confidential adolescent health information in patient portals presents unique challenges. Adolescent patients and guardians electronically access medical records and communicate with providers via portals. In confidential matters like sexual health, ensuring confidentiality is crucial. A key aspect of confidential portals is ensuring that the account is registered to and utilized by the intended user. Inappropriately registered or guardian-accessed adolescent portal accounts may lead to confidentiality breaches. Methods: We used a quality improvement framework to develop screening methodologies to flag guardian-accessible accounts. Accounts of patients aged 12-17 were flagged via manual review of account emails and natural language processing of portal messages. We implemented a reconciliation program to correct affected accounts' registered email. Clinics were notified about sign-up errors and educated on sign-up workflow. An electronic alert was created to check the adolescent's email prior to account activation. Results: After initial screening, 2,307 of 3,701 (62%) adolescent accounts were flagged as registered with a guardian's email. Those accounts were notified to resolve their logins. After five notifications over 8 weeks, 266 of 2,307 accounts (12%) were corrected;the remaining 2,041 (88%) were deactivated. Conclusions: The finding that 62% of adolescent portal accounts were used/accessed by guardians has significant confidentiality implications. In the context of the Cures Act Final Rule and increased information sharing, our institution's experience with ensuring appropriate access to adolescent portal accounts is necessary, timely, and relevant. This study highlights ways to improve patient portal confidentiality and prompts institutions caring for adolescents to review their systems and processes. (c) 2021 Society for Adolescent Health and Medicine. All rights reserved.

关键词： Russia   Ukraine   Uniform State Exam (USE)   External Independent Assessment (EIA)   Exit exams   Multiple-choice problems   Complete-explanation problems  

摘要： This paper is devoted to changes in the way in which mathematical assessment is conducted in Russia and Ukraine, the two largest states formed after the collapse of the Soviet Union. Previously, in the USSR, there existed two parallel systems of examinations, as follows: exit exams, which were taken by schoolchildren graduating from high schools, and which were conducted using the same texts across the entire territory of each Soviet republic;and entrance exams, which each college conducted independently (with the approval of the Ministry). In the new states, a gradual transition occurred to conducting so-called uniform exams, in which exit and entrance exams were combined. This change reflected society's quest for a fair and effective system, which could avoid corruption, unfairness toward different categories of students, and the like. In this paper, examinations are analyzed as an expression of society's influence on the teaching of mathematics. Consequently, the paper analyzes, on the one hand, the stages in the appearance and formation of examination procedures, the problems offered on exams, and the influence of exams on the teaching of mathematics;and on the other hand, the attitude toward exams in society, discussion of them in the press, and other general issues. A necessary space in the paper is allocated to background information, with a discussion of how exams were conducted in the USSR and of the general changes that have taken place in both countries.

关键词： NEXAFS   pump-probe   porphyrin   ultrafast X-ray absorption   pseudoisocyanine   TD-DFT  

摘要： The extension of the pump-probe approach known from UV/VIS spectroscopy to very short wavelengths together with advanced simulation techniques allows a detailed analysis of excited-state dynamics in organic molecules or biomolecular structures on a nanosecond to femtosecond time level. Optical pump soft X-ray probe spectroscopy is a relatively new approach to detect and characterize optically dark states in organic molecules, exciton dynamics or transient ligand-to-metal charge transfer states. In this paper, we describe two experimental setups for transient soft X-ray absorption spectroscopy based on an LPP emitting picosecond and sub-nanosecond soft X-ray pulses in the photon energy range between 50 and 1500 eV. We apply these setups for near-edge X-ray absorption fine structure (NEXAFS) investigations of thin films of a metal-free porphyrin, an aggregate forming carbocyanine and a nickel oxide molecule. NEXAFS investigations have been carried out at the carbon, nitrogen and oxygen K-edge as well as on the Ni L-edge. From time-resolved NEXAFS carbon, K-edge measurements of the metal-free porphyrin first insights into a long-lived trap state are gained. Our findings are discussed and compared with density functional theory calculations.

关键词： 磁共振弥散张量成像   脑肿瘤   放射治疗  

摘要： 目的:分析探讨磁共振弥散张量成像在脑肿瘤放射治疗中的应用价值.方法:将我院2020年12月-2021年2月30例脑肿瘤患者纳入研究范畴,对患者实施磁共振弥散张量成像检查.结果:经过检查之后,分析患者的病理图像可得,患者的脑部有部分脑白质均匀强化,伴有囊性变,肿瘤会破坏纤维束使得两侧不对称;按照FA值的不同,能够明显分辨出一些患者的瘤周水肿呈现出高级别,还有部分呈现出低级别(P<0.05).结论:在脑肿瘤放射治疗中科学应用磁共振弥散张量成像能够取得良好的效果,可予以患者科学可行的放射治疗方案,对患者的治疗过程可起积极影响.

摘要： 提出了一种基于绝缘层上硅波导的全刻蚀布拉格光栅滤波器。该器件可通过对顶部硅的一步刻蚀来实现，其特性使布拉格波长的调谐更加灵敏和有效。仿真研究结果表明，其一阶和三阶光栅的周期对波长调谐系数分别为33 nm/nm和11 nm/nm，光栅刻槽折射率对波长的调谐系数为1 nm/0.006。将光栅脊与刻槽的小折射率差与高阶光栅相结合，可以实现1 550 nm波段更窄带宽的全刻蚀光栅滤波器。

关键词： 扩散张量成像   视神经   各向异性分数   表观扩散系数  

摘要： 目的 探讨3.0T MR扩散张量成像(DTI)定量诊断外伤后视神经挫伤的价值.方法 对15例单侧眼眶外伤、临床诊断为外伤后单侧视神经挫伤的患者行常规眼眶MRI扫描及视神经DTI扫描.分别测量患侧与健侧眶内段视神经的各向异性分数(FA)值、表观扩散系数(ADC)值.采用配对样本t检验统计分析患侧与健侧视神经FA值与ADC值的差异,P<0.01为有统计学差异.结果 常规MRI可以清晰显示患侧与健侧视神经,部分患侧眶内段视神经稍增粗、T2 WI信号稍增高,未见明显断裂和移位征象.患侧视神经FA及ADC值分别为0.34±0.07、(1.34±0.19)×10-3 mm2/s,健侧视神经FA及ADC值分别为0.57±0.09、(0.95±0.17)×10-3 mm2/s,患侧较健侧FA值显著降低(t=8.0,P<0.01)、ADC值显著升高(t=3.2,P<0.01).结论 MR DTI可以定量视神经挫伤改变,有望成为视神经挫伤早期诊断和疗效随访的重要检查手段.