Source-density mapping of human visual receptive fields using scalp electrodes

Summary A triangular array of 20 electrodes spaced by 1.5 cm was used to record the distribution of current source-densities at 12 locations over the occipital scalp, in response to tachistoscopic presentation of a 1/2° × 1/2° scanning pattern element which explored a 2° × 2° area of the visual field. Single scalp locations had visual receptive fields of the order of 1°–2° in diameter, their shape varying somewhat according to the response in question. Source density analysis can resolve details of the AEP scalp map to better than 1 cm. Even with a 1/2° × 1/2° stimulus, averages of only a few tens of sweeps gave adequate signal-to-noise ratios.     

Activation of the human posterior parietal cortex by median nerve stimulation

We recorded somatosensory evoked magnetic fields from ten healthy, right-handed subjects with a 122-channel whole-scalp SQUID magnetometer. The stimuli, exceeding the motor threshold, were delivered alternately to the left and right median nerves at the wrists, with interstimulus intervals of 1, 3, and 5 s. The first responses, peaking around 20 and 35 ms, were explained by activation of the contralateral primary somatosensory cortex (SI) hand area. All subjects showed additional deflections which peaked after 85 ms; the source locations agreed with the sites of the secondary somatosensory cortices (SII) in both hemispheres. The SII responses were typically stronger in the left than the right hemisphere. All subjects had an additional source, not previously reported in human evoked response data, in the contralateral parietal cortex. This source was posterior and medial to the SI hand area, and evidently in the wall of the postcentral sulcus. It was most active at 70–110 ms.     

《针灸逢源》耳病辨治规律探析

对《针灸逢源》中耳病相关内容进行整理分析,归纳该书耳病辨治规律。《针灸逢源》记载的耳病主要有耳聋、耳鸣、耵耳、聤耳、耳疮、耳衄,书中认为耳病由脏腑或经络异常导致,且有虚实之分。在治疗上以针灸为主,对耵耳、聤耳、耳衄还可运用中药治疗。取穴上阳经腧穴多于阴经腧穴,使用频次最多的穴位为听会穴,特定穴中五输穴使用频次较高,选穴分布以上肢部和头面颈项部为主。     

高效液相色谱法同时测定水源水中三种微囊藻毒素

目的 建立一种同时测定水源水中三种微囊藻毒素（MC-LR、MC-RR、MC-YR）的高效液相色谱（high performance liquid chromatography,HPLC）方法。 方法 取500 mL水样,0.45 μm滤膜过滤,滤液过C18柱,依次用10 mL超纯水、20 mL 20%甲醇溶液淋洗,15 mL 80% 甲醇溶液（加入0.05%三氟乙酸）洗脱,蒸发浓缩吹干,溶于1 mL超纯水,待测。采用固相萃取柱,流动相为0.1%磷酸水溶液-乙腈（67∶33）,流速1.0  mL/min,柱温45℃,在238 nm波长紫外线检测器检测。结果 MC-LR、MC-RR和MC-YR 在 0.05~1.00 μg/mL范围内线性良好（r=0.9987、0.9992和0.9997）,且峰形较好;回收率均在80%~110%,相对标准偏差（relative standard deviation,RSD）为5.0%~9.6%;MC-LR、MC-RR和MC-YR的方法检出限（limit of detection,LOD）分别为0.028 μg/L、0.037 μg/L和0.056 μg/L。结论 本方法准确度、灵敏度、回收率高,重现性好,可用于水源水中MC-LR、MC-RR、MC-YR同时检测。     

Single dipole localization: Some numerical aspects and a practical rejection criterion for the fitted parameters

Summary There have been a number of attempts in the last years to localize the generators of brain electromagnetic activity, considering one current dipole as the source model. Single Dipole Localization (SDL) requires the selection of an optimization algorithm (OA). General aspects related with the selection, implementation and evaluation of some of the OA employed for SDL are discussed in this paper. Specifically the performance of two algorithms, those of Hooke-Jeeves and Levenberg-Marquardt, are tested by simulations. Suggestions for including restrictions to the dipole position and comments about some commonly used measures of the goodness of fit are given. Examples of erroneous implementations of these algorithms are also illustrated. A simple graphic rejection criterion, which can be easily used by inexperienced researchers, is introduced and tested in noisy and noise free simulations.The authors are grateful to Roberto D. Pascual Marqui for programming the Hooke-Jeeves algorithm.     

Dipole Localization and Test-Retest Reliability of Frequency and Duration Mismatch Negativity Generator Processes

The mismatch negativity (MMN) is an event related potential component elicited by changes in duration, frequency or intensity of the stimuli during repetitive series of equal standard stimuli. In the present study we compared duration and frequency MMN using dipole source analysis concerning both the test-retest reliability of MMN-amplitudes and the locations of the potential sources. Furthermore, the influence of attention for test-retest-reliability was studied. Therefore, two groups of healthy subjects were investigated with different attentional manipulations. Twenty-one healthy subjects had to perform a visual attention task during the recording and 21 healthy subjects had no additional task to perform. All subjects were studied twice with a time interval of 3 weeks. Test-retest reliability was sufficiently high for the frequency but slightly lower for the duration MMN. The locations of the frequency and duration MMN-dipoles were in the auditory cortex with a more anterior and caudal location for the frequency MMN-dipoles. The latter finding supports the hypothesis that the frequency and duration MMNs have separate neuronal generators.     

Regional specificity of age effects on the neural correlates of episodic retrieval

We investigated age-related differences in episodic retrieval using a source memory procedure. Age-related differences in retrieval-related activity were analyzed in conditions where source recollection performance was statistically equivalent in young and older subjects. Analyses of BOLD activity revealed a network of regions where recollection effects were equivalent in magnitude in the two age groups. There were no regions where these effects were of greater magnitude in young than in older subjects. In some regions, however, there was a crossover interaction, such that retrieval-related effects reversed in direction between the two age groups. Further analyses of these interactions revealed a dissociation between a posterior hippocampal region where recollection-related activity was confined to the older group, and right fusiform and occipital regions where, in the young group only, activity elicited by studied items was of lower magnitude than activity to new items. We interpret the first of these age-related effects as an example of ‘over-recruitment’ in response to decline in neural efficiency, and discuss whether the second effect indexes an age-related decline in repetition priming.     

某医院粒籽源永久性植入治疗病房的剂量监测结果分析

目的 研究某医院粒籽源永久性植入治疗病房内的外照射剂量水平和分布情况,对其辐射风险进行评估,为加强粒籽源永久性植入治疗放射工作人员的放射防护与监督提供科学依据,同时提出合理化的辐射防护建议。方法 采用热释光剂量测量方法对粒籽源永久性植入治疗病房内10类区域的剂量水平进行为期1年的监测,并结合病人植入粒籽源数目和住院天数进行剂量分析。结果 该病区一年内共收住病人1232人次,其中行粒籽源永久性植入治疗病人432人次（190人）,共植入粒籽源2.746843×10¹¹ Bq（7423.9 mCi）,人均6.3566×10⁸ Bq（17.18 mCi）,粒籽源永久性植入治疗病人年度住院天数2478天,平均住院6天。热释光剂量监测结果表明,各监测点处的剂量范围为0.23～13.94 mSv,均值为3.37 mSv,中值为1.90 mSv。其中病床两侧和输液架处的剂量范围明显高于其他点位处,经剂量/活度和剂量/（活度·天）分析,其差异依旧存在,均存在统计学差异。结论 该粒籽源永久性植入病房内存在外照射剂量偏高的点位,医护人员和陪护人员应减少在此点位居留的时间或远离此点位。医护人员年度个人剂量监测结果远低于国家标准要求,亦低于本次实验点位剂量监测结果,与医护人员的实际工作和居留情况有关。工作人员在穿戴防护用品的情况下,在剂量安全范围内,可适当增加粒籽植入活度和住院天数。患者在术后穿戴防护,可明显降低其对医护人员的外照射剂量。     

源文献挖掘方法在筛查低复制比抄袭论文中的应用

【目的】 报告应用源文献挖掘方法从低复制比投稿中筛查出的抄袭论文的特点,并详细介绍这一筛查方法,为期刊编辑认识和筛查这类抄袭论文提供借鉴。【方法】 选择近3年《山东医药》的来稿中AMLC检测复制比<20%的2421篇论文,应用源文献挖掘方法,先常规检索所有论文的中、英文题名,进一步对有可疑指征的论文进行重点筛查。从各数据库中检出可疑源文献后,与投稿论文进行全文比对,查证是否存在抄袭。【结果】 共查证得到存在确凿证据的抄袭论文30篇,分别为抄袭他人9篇、抄袭团队10篇和自我抄袭11篇。其中19篇(63.3%)抄袭论文的源文献通过中、英文题名检出,11篇(36.7%)的源文献通过对可疑论文的重点筛查检出。【结论】 低复制比的投稿论文中仍存在多种类型的抄袭论文,查重后再进行抄袭筛查是必要的;应用源文献挖掘方法有助于检出雷同源文献进而查证抄袭。     

湖南省洪涝灾害高发地区钩端螺旋体病流行因素的研究

目的研究湖南省洪涝灾害高发地区钩端螺旋体病的流行因素。方法选择洞庭湖区6个县研究传染源密度、带茵情况和自然人群、病人与动物抗体水平，按国家有关标准进行实验室和现场工作。结果(1)传染源：灭鼠前、后和钩体病流行后期鼠密度分别为7．02％、2．31％和4．64％，优势鼠种为黑线姬鼠，灭鼠后鼠密度下降了67．09％：村民家庭家畜饲养以圈养形式占99．15％，喂商品混合饲料的占72．33％。(2)病原学：对鼠、猪、犬和病人的标本进行钩体培养，分离出82株钩体，黄疸出血群占70．73％，1株国内新型茵，黑线姬鼠分离率高达11．03％。(3)血清学：检测1263名自然人15个群钩体抗体，一群以上抗体阳性率未接种钩体苗为50．88％，接种一针四价钩体为72．55％，人群抗体有14群之多；检测85例病人双份血清抗体，确诊63例，符合率74．11％，黄疸出血群感染比例最高；流行季节牛、犬和出栏猪抗体分别有14、8和7个群，牛阳性率最高。结论流行前灭鼠效果好，不仅降低了鼠密度，还降低了带茵率；主要传染源是鼠和牛，牛作为传染源的意义大于猪和犬；人群接种一针四价钩体菌苗亦有效；病人感染黄疸出血、澳洲和秋季群为多。