一种应用于电容式微机械陀螺的改进型积分器研究

电容式微机械陀螺通常都采用积分器作为前级输入模块,实现高频调制和电容电压转换的功能.传统积分器的转换增益与反馈电容成反比,而反馈电容的值太小,会引起电路自激震荡,因此传统积分器对有用信号的放大倍数有限,系统的信噪比较低.对此,提出了一种应用于电容式微机械陀螺的改进型积分器,这种积分器的转换增益可以通过调节电容比值而得到较大值,因此能够提高系统的信噪比.该文在分别分析两种积分器工作原理的基础上,通过理论分析及仿真结果对比,证明了改进型积分器能够提高有用信号的放大倍数.     

Skeleton Changes Induced by Horse Riding on Medieval Skeletal Remains from Croatia

Skeletal remains of 35 individuals from the Croatian excavation site Kamen Most – Kaldrma from the fourteenth to fifteenth centuries were analyzed anthropologically. Due to specific skeletal characteristics, eight of them were analyzed in great detail in this study. The results of additional analysis indicated that all bone elements, except pelves, of all eight persons belonged to males. All pelvic girdle have characteristics of female sex and pronounced muscle attachments that are both indicative of horse riding. All eight persons had at least two of six changes on femora indicative of horse riding. Vertebrae of seven persons (one person did not have preserved vertebrae) have Schmorl's nodes. Signs of advanced osteoarthritis were found on all joints in all eight persons. All of them also have visible signs of periostitis especially on lower extremities. Pathological signs of trauma were found in five persons. Two of them had skull fractures and the rest had fractures of extremities which are also characteristic for horse riders. The average age of all eight persons was above 45 years at death. DNA analysis confirmed male sex for seven individuals. The results were additionally confirmed by later archeological findings of tombstones with illustrations of horse riders.     

Diversity of Terrestrial Cyanobacteria Colonizing Selected Stone Monuments in Serbia

The presence of biofilms on stone monuments can lead to biodeterioration processes that significantly lower not only the aesthetic value of cultural heritage sites but also cause considerable physical and chemical damage to stone surfaces. In terrestrial environments, cyanobacteria have a significant role in biofilm formation on a variety of natural and artificial stone substrata, including granite, sandstone, limestone, lime mortar, etc. Studies on cyanobacterial diversity and estimation of biodeteriorative activity on stone cultural heritage objects can be very important for conservators and restorers, and cyanobacteria removal from stone monuments is currently a great challenge for conservation science. In that sense, the diversity of terrestrial cyanobacteria was investigated at six localities in Serbia. Samples for cyanobacterial analyses were taken from surface biofilms covering different substrata: granite and lime mortar (The Monument to the Unknown Hero), sandstone (Branko's Bridge, Eiffel’s Lock) and carbonate rock (Medieval tombstones from Mramorje and Rasti?te, Gradac Monastery). A total of 18 cyanobacterial taxa were identified. The highest diversity was found on carbonate rock, followed by sandstone. Cyanobacteria were also recorded on an artificial substratum – lime mortar, while cyanobacteria were not found on granite. All detected cyanobacteria seriously impaired the structural and aesthetic integrity of the studied monuments via mechanical and chemical actions, so their presence must not be overlooked.     

在虚拟互动中落实探究--《宇宙@Science》网站的设计与应用

本文从教学实践中遇到的问题出发,从建站缘起、建站思想、网站表达特点、教学效果等几个方面,探讨了虚拟互动教学软件在天文地理教学中设计与应用,并通过网络教学实例说明如何诱导学生将科学探究落到实处,培养学生的高级思维能力。     

德语DSH考试听力理解的常见六大题型分析--以德国弗莱堡大学2007-2013年真题为例

DSH考试是为外国学生申请在德国高校入学而组织的一项语言考试,能够全面考察考生的德语语言水平。其中听力理解考试是重要的组成部分,也是中国考生的传统弱项。为了对考生的听力技能进行全面客观的考察,DSH听力考试的题目设置也往往灵活多样,难度逐级递增,并与其他语言能力紧密结合。本文选取德国弗莱堡大学2007-2013年间六次DSH考试的听力理解部分,解析DSH听力考试的组织形式、评估标准以及常见题目类型,其中重点总结了六大最常见的题型,即填空、补充表格、判断正误、排列顺序、理解归纳和总结复述。此外,本文通过分析DSH听力考试的特点,总结解题技巧,给中国考生备考DSH提供了科学的建议。     

Paraoxonase 1 activity and phenotype distribution in premenopausal and postmenopausal women

Introduction

Postmenopausal women have higher risk of cardiovascular disease. One of the contributing factors could be reduced activity of anti-atherogenic enzyme paraoxonase 1 (PON1). The aim of this study was to examine differences in the lipid status, paraoxonase and arylesterase PON1 activities and PON1 phenotype in women with regular menstrual cycle and in postmenopausal women.

Materials and methods:

The study included 51 women in reproductive age (25 in follicular and 26 in luteal phase of the menstrual cycle) and 23 women in postmenopause. Lipid parameters in sera were determined using original reagents and according to manufacturer protocol. PON1 activity in serum was assessed by spectrophotometric method with substrates: paraoxon and phenylacetate. PON1 phenotype was determined by double substrate method.

Results:

Compared to the women in follicular and luteal phase, postmenopausal women have significantly higher concentration of triglyceride [0.9 (0.7–1.3), 0.7 (0.6–1.0) vs. 1.5 (0.9–1.7) mmol/L; P = 0.002], cholesterol [5.10 (4.78–6.10), 5.05 (4.70–5.40) vs. 6.30 (5.73–7.23) mmol/L; P < 0.001], LDL [3.00 (2.56–3.63), 3.00 (2.70–3.70) vs. 3.90 (3.23–4.50) mmol/L; P < 0.001], and apolipoprotein B [0.88 (0.75–1.00), 0.79 (0.68–1.00) vs. 1.07 (0.90–1.24) mmol/L; P = 0.002]. PON1 basal [104 (66–260), 106 (63–250) vs. 93 (71–165) U/L; P = 0.847] and salt-stimulated paraoxonase activity [210 (131–462), 211 (120–442) vs. 180 (139–296) U/L; P = 0.857] as well as arylesterase activity [74 (63–82), 70 (54–91) vs. 70 (60–81) kU/L; P = 0.906] and PON1 phenotype (P = 0.810) were not different in the study groups.

Conclusion:

There are no differences in PON1 activity and PON1 phenotype between women with regular menstrual cycle and postmenopausal women.     

基于DDS的频率特性测试仪的设计

本文频率特性测试仪采用单片机最小系统为控制核心,由正弦信号发生器、数据采集存储、处理、显示等功能模块组成,通过键盘控制来实现幅频特性的测量,包括参数预置、点测结果的显示,以及用普通示波器显示幅频特性曲线。系统采用数字控制DDS芯片AD9850产生100Hz～100KHz正弦信号,频率值与步长均能灵活准确地预置,被测网络采用有源带通双T网络,中心频率及带宽均达到要求。     

All good readers are the same,but every low-skilled reader is different: an eye-tracking study using PISA data

PISA results show that a considerable number of 15-year-old pupils after 8 to 10 years of schooling have a low level of functional reading literacy, as defined in the PISA framework. While PISA results help identify the level of reading competency, they do not reveal what might be the reasons why some students fail to solve the tasks. One way to explore the difficulties students encounter while solving PISA reading tasks is to track their eye movements during reading. The main aim of this study was to explore the similarities and differences in eye movement patterns between students with high and low scores on PISA reading tasks. A sample of 92 students took part in the pre-test, which was based on PISA items, and administered to identify groups of students with high and low PISA reading scores. Based on student pre-test results, 20 students were selected for the main, eye-tracking test—10 participants with low scores and 10 with high scores. The eye-tracking test consisted of four different released PISA reading tasks, three of them continuous and one non-continuous. The continuous items were followed by one multiple-choice question each at L1, L2, and L3 levels of difficulty. The non-continuous text was followed by three multiple-choice questions (also L1–L3).Three main findings were the following: regarding saccadic amplitudes, the reading was found to be less fluent for the low-skilled group; according to the heat maps, they had difficulty finding the relevant material; and taking into account standard deviations of eye-tracking measures, the variability was found to be larger in this group. Taken together, the findings of this study show that the PISA results differentiating low- and high-scoring groups go hand in hand with insights from more fine-grained eye-tracking measurements.     

科学发展观中的哲学精神

科学发展观蕴涵着丰富的哲学精神 ,本文从科学发展观的本质、目的、内涵、要求四个方面来论述其哲学精神。科学发展观的深层本质是重新确立科学的马克思主义生产实践观 ;科学发展观的最终目的是马克思主义哲学最高价值追求在现时代的新发展与真正实践 ;科学发展观的基本内涵是马克思主义唯物辩证法和唯物史观内在要求的生动体现 ;科学发展观的根本要求是社会发展要坚持以马克思主义哲学的世界观和方法论为指导