广州市大气PM2.5中多环芳烃的现状及分布情况

目的 了解广州市大气PM_2.5中多环芳烃在不同时间、不同地区内的分布特征。 方法 于2018年在广州市越秀区(市区),从化区(农村)和番禺区(市郊)采集PM_2.5有效样品252份,用高效液相色谱法测定样品中16种多环芳烃的浓度,以分析不同地区、不同时间及季节间的分布特征和变化趋势。结果 广州市大气PM_2.5中16种多环芳烃均有检出,但质量浓度处于较低水平,年均值为(4.907±3.642)ng/m³。PM_2.5及多环芳烃的质量浓度呈现明显的季节性波动,表现为冬春季较高,夏秋季较低,不同季节差异有统计学意义(F=3.624～72.439,均P<0.05)。市区为(54.321±35.106)μg/m³,农村地区为(46.298±25.933)μg/m³,市郊PM_2.5的质量浓度为(51.821±30.033)μg/m³,差异无统计学意义(F=1.513,P>0.05),多环芳烃中萘、苯并[a]芘、二苯并[a,h]蒽、茚并[1,2,3-cd]芘的污染水平在不同地区之间差异有统计学意义(F=4.428～6.422,P<0.05),农村高于市区和市郊。结论 广州市大气PM_2.5中多环芳烃污染水平较低,呈现明显的季节性波动和城乡差别。     

屈光参差性弱视3种空间频率多导视觉诱发电位地形图研究

目的：研究屈光参差性弱视儿童三种空间频率多导视觉诱发电位地形图的变化特征,探讨弱视的发生机理。方法：选取13.7'、27.5'及55.3'种方格对单眼屈光参差性弱视眼及对侧眼进行多导视觉诱发电位地形图的研究。结果：（1）3种空间频率所有导致,弱视眼的P1潜伏期同正常组相比显著延迟;弱视眼的N1P1振幅在枕区导联降低。（2）P1潜伏期及N1P1振幅的分布不同于正常组。（3）地形图：枕区高电位活动不对称分布增多,以向右侧偏位为主,并出现半视野刺激样反应。（4）弱视对侧眼的P1潜伏期及N1P1振幅的异常主要发生在高空间频率。结论：屈光参差性弱视眼的P和M通道可能都受到了视觉发育敏感期异常视觉经验的影响;左侧半球的视皮层或传导通路更易受到发育早期不正常的视觉经历的影响;弱视对侧眼也存在一定程度的异常改变。     

基于德兴市中药材种植统计数据的时空挖掘分析

目的:对江西省德兴市中药材种植统计数据的空间和时间特征进行挖掘分析,提供研究空间和时间相结合的中药材种植特征分析方法,为指导德兴市中药材生产和宏观决策提供可靠的数据和方法。方法:利用德兴市中药材统计数据与土地利用等数据相结合,在乡镇尺度上通过统计分析、空间自相关分析等方法对德兴市各乡镇中药材种植面积、种类、结构多个空间分异特征及机制进行分析。结果:德兴市各乡镇中药材种植面积、种类和结构在空间上差异很大,种植面积及种类都较多的乡镇土地利用类型主要以耕地和林地为主。2018—2021年,德兴市中药材种植总面积、总产量和总产值都呈逐年递增趋势。结论:研究结果可为德兴市中药产业布局提供数据支撑,有助于政府制定合理的中药材种植规划,确保市场的供需平衡,避免出现供应不足或过剩等情况。     

The geographic distribution of un-immunized children in Ontario,Canada: Hotspot detection using Bayesian spatial analysis

BackgroundIn Ontario, Canada, little is currently known about the extent to which un-immunized children may cluster geographically. Our objectives were to: describe the geographic distribution of fully un-immunized children; identify geographic clusters (hotspots) of un-immunized children; and to characterize the contribution of spatial effects and covariates on hotspots, where found.MethodsOur analytic cohort consisted of Ontario students aged 7–17 years in the 2016–2017 school year. We defined students as un-immunized if they had zero doses of any vaccine and a non-medical exemption recorded in Ontario’s registry. We calculated unadjusted proportions of un-immunized students by Census Subdivision (CSD) and then used a sequential approach to identify hotspots starting first with hotspot identification at the CSD level and then probed identified hotspots further by Dissemination Area (DA) and including covariates. Hotspots were identified using the Besag-York-Mollie Bayesian spatial model and were defined as areas with >95% probability of having two times the proportion of un-immunized students, relative to the province overall.ResultsWe identified 15,208 (0.94%) un-immunized children within our cohort consisting of more than 1.61 million students. Unadjusted proportions of un-immunized students varied greatly by geography, ranging from 0% to 21.5% by CSD. We identified 16 hotspot CSDs which clustered in five distinct areas, all of which were located in southern Ontario. The contribution of covariates and spatial effects on the risk of having un-immunized students varied greatly across hotspot areas.ConclusionsAlthough the provincial proportion (0.94%) of un-immunized students is small, geographical clustering of such students is evident in Ontario and in some areas presents an important risk for future outbreaks. Further qualitative work within these hotspot areas would be a helpful next step to better characterize the factors associated with vaccine refusal in these communities.     

不同空间插值方法在钠摄入量估算中的应用

目的采用空间插值法对缺失膳食钠摄入量数据的地区进行摄入量估算。方法膳食钠消费数据来自2010—2012年中国居民营养与健康状况监测,调查采用多阶段分层与人口成比例的整群随机抽样方法,共调查了150个区县20岁及以上居民的膳食消费数据。运用连续3天24小时膳食回顾法结合家庭调味品称重法,进行面对面访谈共收集了48826名成年人膳食钠摄入量数据,计算膳食钠消费量平均数据。比较反距离权重法、普通克里金插值法、协同克里金插值法和回归克里金插值法等空间分析技术对膳食钠摄入量估算的精度,并选用插值精度最高的空间分析方法,绘制全国各区县的人均每日膳食钠摄入量预测趋势面,对各省膳食钠摄入量进行估算。结果2010—2012年中国居民的膳食钠平均摄入量为5.18g,其中男性平均摄入量为5.33g,女性平均摄入量为5.03g。比较多种空间分析技术估算膳食钠摄入量的精度发现,回归克里金插值法优于其他3种方法,其均方根误差和平均绝对误差分别为0.54和0.44。利用回归克里金插值法对全国各地区膳食钠摄入量进行估算,经人口加权计算得到全国膳食钠摄入量估算值为5.17g/d,全国男性膳食钠摄入量估算值为5.33g/d,女性膳食钠摄入量估算值为5.01g/d,各年龄组膳食钠的测量值与估算值的差值率均不超过10%。钠摄入量较高的地区为山东省(5.98g/d)、天津市(5.83g/d)和河北省(5.82g/d),摄入量最低的为贵州省(4.27g/d)结论空间插值法可用于对膳食钠消费数据缺失地区的摄入量估算,其中回归克里金插值法估算精度最高。     

青、老年大鼠在Morris水迷宫中的学习记忆行为

本实验观察了22～24月龄老年大鼠和5～6月龄青年大鼠在Morris水迷宫中的学习记忆行为,并用定量分析方法比较两组动物在定位航行及空间搜索试验中的学习记忆,结果表明老年大鼠的寻找平台潜伏期明显延长,而其跨平台次数及在平台象限的游泳路线长度并未减少.提示24月龄老年大鼠获取学习记忆的能力受损伤而保持记忆的能力维持正常,这可能与二种功能衰老的不同速度及不同神经基础有关.     

医学影像数据库的索引及检索技术的研究

随着医学影像数据库数据量的剧增，迫切需要研究高效的索引技术以支持基于图像内容的检索。介绍了医学影像数据库索引技术的特点，比较分析了几种典型的空间数据索引方法（如R树、VA文件、A树、NB树和M树）及其作为医学图像数据库索引的性能。     

In vivo brain (31)P-MRS: measuring the phospholipid resonances at 4 Tesla from small voxels

An optimized phosphorous ((31)P) three-dimensional chemical-shift imaging (3D-CSI) protocol was developed at 4 T to study the phospholipid metabolism from discrete regions in the human brain without the need for (1)H-decoupling or nuclear Overhauser enhancement (NOE). In this study, a spherically bound, weighted average, random point omission 3D-CSI technique was developed and tested, based on methods proposed in the literature. The technique yields a significant (p < 0.001, two-tailed, 5% confidence level) increase in signal-to-noise (SNR) efficiency over conventional 3D-CSI (phantom 32%), without an increase in voxel bleedthrough. An automated time-domain fitting procedure utilizing prior spectral knowledge quantified the individual brain phospholipid metabolites from 15 cm(3) effective (8.0 cm(3) nominal) volumes from the left/right-parieto-occipital cortex and left/right thalamus in 10 normal volunteers. Individual constituents from the phosphomonoester (PME) region; phosphoethanolamine (PEth), phosphocholine (PCh) and the phosphodiester (PDE) region; glycerophosphoethanolamine (GPEth), glycerophosphocholine (GPCh) and membrane phospholipids (MP) were separately quantified to assess the precision of our method at 4 T against previous (1)H-decoupled (31)P-MRS brain studies at lower fields and much larger voxels. Derived concentrations (mM/l tissue) for PEth, PCh, GPEth, GPCh and MP in the left-parieto-occipital cortex were 0.81 +/- 0.21, 0.46 +/- 0.14, 0.74 +/- 0.30, 1.15 +/- 0.43 and 1.54 +/- 0.95 mM, respectively, and 0.94 +/- 0.16, 0.46 +/- 0.17, 0.83 +/- 0.22, 1.14 +/- 0.40 and 1.26 +/- 0.78 mM for the right parieto-occipital cortex. Derived concentrations (mM/l tissue) for PEth, PCh, GPEth, GPCh and MP in the left-thalamus were 0.69 +/- 0.18, 0.42 +/- 0.16, 0.63 +/- 0.20, 1.05 +/- 0.42 and 0.93 +/- 0.56 mM, respectively, and 0.68 +/- 0.24, 0.34 +/- 0.18, 0.60 +/- 0.23, 1.09 +/- 0.36 and 0.74 +/- 0.48 mM for the right-thalamus. This is the first study to our knowledge that has been able to quantify each of these individual phospholipid metabolites from such small voxels in the brain within a clinically reasonable scan time and without (1)H-decoupling or NOE.     

Further evidence for a gene influencing spatial ability

Data for six spatial tests from 927 families of European ancestry, 369 families of Japanese ancestry, and 93 families of Chinese ancestry from the Hawaiian Family Study of Cognition were subjected to unified mixed-model segregation analysis. Father, mother, son, and daughter data sets from each ethnic group were separately age-adjusted and standardized and then separately subjected to transformation procedures to reduce skewness and kurtosis. Families were reassociated prior to segregation analysis. Evidence for a major gene contributing to spatial visualizing ability was obtained for Mental Rotations and Progressive Matrices even with a normalizing transformation which reduced skewness and kurtosis to zero. It was concluded that provision for testing deviation from Mendelian transmission in the unified model protected against false inference of a segregating major gene. Minimizing distributional differences in the components of a data set is an important pretreatment.The results reported here are made possible by the collaboration of a group of investigators (G. C. Ashton, R. C. Johnson, M.-P. Mi, and M. N. Rashad at the University of Hawaii and J. C. DeFries, G. E. McClearn, S. G. Vandenberg, and J. R. Wilson at the University of Colorado) supported by NSF Grant GB 34720 and National Institute of Child Health and Human Development Grant HD 06669. Support for I.B.B. was provided by NIMH Grant MH 14677.     

Variability of the steady-state visually evoked potential: Interindividual variance and intraindividual reproducibility of spatial frequency tuning

At low contrast levels there is good agreement between the psychophysical contrast sensitivity function and the tuning curve of the visually evoked potential (i.e., VEP amplitude vs spatial frequency). At high contrast, however, some researchers have found bimodal VEP tuning curves whereas others have not. We studied the VEP in 22 subjects in a short-term cross-sectional study and in 13 subjects in a longitudinal study over 8 sessions covering 28 days. Grating stimuli with 60% contrast were square-wave modulated in time (7.8 reversals/s) and space (0.06–16 cycles/degree). We found large interindividual variance in the shape of the tuning curves; about half of the subjects showed a unimodal shape, while the other half showed a bimodal one (with a notch between 1 and 2 cycles/degree). These features turned out to be stable in the longitudinal study, where variability could mainly be ascribed to a multiplicative influence common to all spatial frequencies. The marked interindividual differences in the shape of the tuning curve, which seem to be intraindividually stable, may explain previous discrepancies. It is not yet clear why the notch exists in about half of our subjects.