Soft x-ray instrumentation and its applications at the advanced photon source

Knowledge of the intermediate energy range from 0.5-4 keV, bridging the "soft" and "hard" x-ray regions, is relatively underdeveloped. However, recent developments in the techniques of microscopy and magnetic circular dichroism have emphasized the need to operate in this energy range for microelectronic, biological, and materials science related experiments. The strong dipole-allowed 3d to 4f transitions in rare-earth magnetic materials fall in this region, as do the K-shells of many of the second and third row elements of the periodic table. Two beamlines to be constructed at the Advanced Photon Source (APS) have been designed to cover this energy region. The proposed undulator source, the beamline layout, and the experimental programs for these beamlines are described.     

Using cognitive models to develop quality multiple-choice questions

With the recent interest in competency-based education, educators are being challenged to develop more assessment opportunities. As such, there is increased demand for exam content development, which can be a very labor-intense process. An innovative solution to this challenge has been the use of automatic item generation (AIG) to develop multiple-choice questions (MCQs). In AIG, computer technology is used to generate test items from cognitive models (i.e. representations of the knowledge and skills that are required to solve a problem). The main advantage yielded by AIG is the efficiency in generating items. Although technology for AIG relies on a linear programming approach, the same principles can also be used to improve traditional committee-based processes used in the development of MCQs. Using this approach, content experts deconstruct their clinical reasoning process to develop a cognitive model which, in turn, is used to create MCQs. This approach is appealing because it: (1) is efficient; (2) has been shown to produce items with psychometric properties comparable to those generated using a traditional approach; and (3) can be used to assess higher order skills (i.e. application of knowledge). The purpose of this article is to provide a novel framework for the development of high-quality MCQs using cognitive models.     

螺旋CT在肺动脉栓塞诊断中的价值

目的:评价螺旋CT在诊断肺动脉栓塞中的作用。方法:16例肺动脉栓塞患者行螺旋CT肺动脉造影 (SCTA)检查,层厚3mm,扫描时间0.8s,对比剂注射速度3.5ml/s,总量100ml,扫描延迟时间15s。结果:16例 共644支,其中134支肺动脉及分支显示了栓塞,占20.8%。228支肺段肺动脉中,有56支显示肺动脉栓塞,占分 析肺动脉支的24.5%。204支亚段肺动脉中37支显示肺动脉栓塞,占分析肺动脉支15.4%。肺动脉栓塞的CT形 态:①直接征象为不同程度的肺动脉分支内充盈缺损。中心型充盈缺损17支,偏心型充盈缺损44支,附壁血栓型 34支,完全阻塞型39支。②间接征象胸膜下肺梗死灶,内乳动脉一侧增粗,肺纹理稀少,胸水,肺动脉高压。结论: 螺旋CT肺动脉造影是诊断肺动脉栓塞的快速、有效、无创伤的诊断方法。     

大肠侧向发育型肿瘤细胞株的建立及其鉴定

目的 为了深入研究大肠侧向发育型肿瘤(LST)细胞的生物学特性及其发生发展的机制。方法采用人LST组织进行肿瘤细胞建株及细胞分离与原代培养,传代至70代进行细胞鉴定．包括细胞的形态结构分析、染色体分析和免疫组化分析等,并与非LST细胞作对比。结果 LST细胞为上皮来源的肿瘤细胞,多形性上皮细胞占大多数,其有近似肿瘤细胞的生长特性,群体倍增时间为36h;染色体数量为42-66,85％在三倍体范围内,并具有异常染色体核型;免疫组织化学观察ESA、CK20均呈阳性;超微结构具肿瘤细胞样表现和特征。结论成功建立了1个LST细胞株,并命名为LST-R1细胞,为进一步深入研究LST细胞的生物学特性及大肠癌的发生发展机制奠定了基础。     

维甲酸改善单侧输尿管梗阻大鼠肾脏损害的研究

目的:探讨维甲酸对单侧输尿管梗阻(UUO)大鼠肾小管间质损害的保护作用.方法:成年清洁级雄性SD大鼠45只,随机分为假手术组(S组)、UUO组(U组)和治疗组(T组),每组15只.假手术组行左输尿管游离,不结扎;UUO组和治疗组行左输尿管结扎.治疗组术后每天给予5 mg/kg全反式维甲酸(ATRA)皮下注射,假手术组和UUO组注射同体积溶剂.于术后第3、7、14 d观察肾小管损害、肾间质炎性细胞浸润程度,免疫组化法观察病变肾组织趋化因子RANTES和TGF-β1表达.结果:与UUO组相比,治疗组肾间质炎性细胞浸润和肾小管损害程度显著减轻(P＜0.01),肾组织RANTES和TGF-β1表达显著降低(P＜0.01～0.05).结论:维甲酸能减少UUO大鼠肾间质炎性细胞浸润,减轻肾小管损害,抑制RANTES和TGF-β1表达,从而减轻肾脏炎症反应和纤维化.     

全国首台AP1000核电机组安装后周围生活饮用水及食品中90Sr和137Cs放射性水平调查

目的 调查分析全国首台AP1000核电机组安装后周围生活饮用水中⁹⁰Sr和¹³⁷Cs及食品中¹³⁷Cs放射性水平及变化。方法 2012—2019年,选取全国首台AP1000核电机组所在的三门核电站周围的4个生活饮用水监测点,分别在丰水期和枯水期采集并测定⁹⁰Sr和¹³⁷Cs放射性活度浓度;采集当地产大米、包菜、鲫鱼和鲻鱼,测定分析¹³⁷Cs放射性活度浓度。结果 2012—2019年,生活饮用水中⁹⁰Sr和¹³⁷Cs放射性活度浓度范围分别为1.2~9.8、0.2~8.1 mBq/L;食品中¹³⁷Cs放射性活度浓度为1.1×10^-2~2.8×10^-1 Bq/kg,小于《食品中放射性物质限制浓度标准》（GB 14882-94）限制浓度。结论 全国首台AP1000核电机组安装后周围生活饮用水中⁹⁰Sr和¹³⁷Cs及食品中¹³⁷Cs放射性水平平稳,调查数据显示未发现对环境带来影响。     

语言刺激的功能性MR成像在自闭症诊断中的潜在应用价值

目的对自闭症病人给予被动性语言刺激,评价采用功能性磁共振(MR)成像作为判断病人有无语言缺陷的客观指标的可行性。材料与方法本研究为前瞻性研究,研究方     

Brain abscess and necrotic brain tumor: discrimination with proton MR spectroscopy and diffusion-weighted imaging

BACKGROUND AND PURPOSE: Discriminating pyogenic brain abscesses from cystic or necrotic tumors is sometimes difficult with CT or MR imaging. We compared findings of proton MR spectroscopy ((1)H-MRS) with those of diffusion-weighted imaging to determine which technique was more effective for this differential diagnosis. METHODS: Fourteen patients (necrotic or cystic tumor [n = 7]; pyogenic abscess [n = 7]) who underwent 1.5-T (1)H-MRS and diffusion-weighted imaging and had findings of ring-shaped enhancement after contrast agent administration were enrolled in this study. Diffusion-weighted imaging was performed with a single-shot spin-echo echo-planar pulse sequence (b = 1000 s/mm(2)). The apparent diffusion coefficient and ratio were also measured. RESULTS: Spectra for two patients were unacceptable because of either poor shimming conditions or contamination from neighboring fat. Spectra in three of five patients with abscess had lactate, amino acids (including valine, alanine, and leucine), and acetate peaks; one of the three spectra had an additional peak of succinate. In one patient with abscess treated by antibiotics, only lactate and lipid peaks were detected. Spectra for four of seven patients with cystic or necrotic tumors showed only lactate peaks. Lactate and lipids were found in three patients with tumors. Hyperintensity was seen in all the pyogenic abscess cavities and hypointensity in all the cystic and necrotic tumors on diffusion-weighted images. CONCLUSION: (1)H-MRS and diffusion-weighted imaging are useful for differentiating brain abscess from brain tumor, but the latter requires less time and is more accurate than is (1)H-MRS. (1)H-MRS is probably more limited in cases of smaller peripheral lesions, skull base lesions, and treated abscesses.     

早产儿鼻饲胃管长度体表测量方法的改良

目的探讨早产儿鼻饲胃管长度的最佳体表测量方法,减少喂养不耐受及并发症的发生。方法将118例鼻饲早产儿随机分为对照组(60例)和观察组(58例),对照组胃管置入长度采用"耳垂-鼻尖-剑突"测量法,观察组采用"眉弓-剑突"测量法,比较两组呕吐、胃潴留及胃出血发生率。结果对照组呕吐、胃潴留及胃出血发生率显著高于观察组(P0.05,P0.01)。结论采用"眉弓-剑突"测量早产儿胃管置入长度,可使胃管正好到达胃内又不至于在胃内盘曲,可减少呕吐、胃潴留等喂养不耐受及胃出血等并发症的发生。