雷电在东西方文化中的差异

 狂风呼啸,云海翻腾。刹那间,电闪雷鸣,暴雨滂沱……雷电,自然界中最惊心动魄,威力巨大的瞬间释放的能源之一,自它远古诞生之日起,就对地球表面大气的形成和氧气的制造,乃至地球上生命的起源及人类的进化都起到了难以估量的作用。一、雷电在东方演绎成历史悠久意义深远的“龙”文化龙,是东方文化的标志,是中华民族的图腾。图腾是集崇拜、敬畏、恐惧和想象于一身的虚拟画像。那么,龙是怎样产生的?它最早的文字记载源于何处?远古时期,人们常常受到雷电袭击,但不明其理,进而产生雷龙的端倪。如《投荒杂录》中就有,一群百姓遇上大雷电,雷鸣电闪中,天上出现一头“豕首鳞身”的怪物,形状奇特,向人们扑来,人们慌忙举刀自卫。     

泡沫物理学史拾萃

人们对泡沫习以为常,却很难理解它的奇特性质,比如几乎完全由空气组成的泡沫,既能像固体一样发生弹性形变,又能像流体一样发生流动,这正是泡沫物理学的研究内容之一.泡沫物理是一门古老的学科,早在19世纪中下叶,气泡和泡沫结构静力学的描述已经完美,之后没有大的发展,直到1990年前后,随着流体力学、微观显像技术和计算技术等学科的发展,以及受材料科学和工业生产的需求,泡沫物理研究再次活跃起来.文章第一作者曾跟随英国皇家学会院士Denis Weaire从事泡沫物理研究多年,在他的演讲和个人收藏中,文章作者积累了一些材料,在此基础上,又仔细查阅了相关文献,整理成此文,它基本概括了泡沫结构静力学发展历程中的重要事件.     

物理学咬文嚼字之六十自由与束缚

Free及与其相反的词如forced,confined,constrained,coercive,binding,bonding,bound,等等,都出现在物理学概念中。自由不过是骨感的想象,束缚才是丰满的现实。     

既见树木,又见森林——高中物理试卷讲评课的策略探究

试卷讲评是高中物理的重要组成部分．一堂高质量的讲评课,需要教师精心准备,充分调动学生的积极性,准确“把脉”,有的放矢,总结方法,延伸发散,并及时巩固,才能从根本上达到试卷讲评的目的．而当前试卷讲评课堂教学,我们发现,有的教师把试卷讲评课上成了答案核对课,热衷于单向的向学生灌输正确答案,学生被动地听讲,机械地记录．有的教师满堂灌式的讲评,面面俱到,没有重点,不分主次,只注重正确答案而缺乏理论分析和技法指导等．实践证明,这种机械地从头到尾以题论题,全体核对答案的做法其效果是事倍功半的．原因何在？     

物理学咬文嚼字之三十四 主观乎,客观乎?

Subject,object在英文物理学和哲学文献中随处可见,相关词汇如subjectivism,objectivism,subjectivity,objectivity,subjective idealism,objective materialism等差不多是永恒的哲学话题,而subject-object division则是量子力学不容回避的现实问题.因为subject,object的词义特别繁复,基于汉译客观与主观的理解常让人一头雾水.     

上帝派往人间的使者——“拉普拉斯妖”随笔之一

一 古希腊的神话中有许多关于妖的故事,给我印象最深的是蛇发女妖玛杜莎,头发是一条条活蛇,发尖是蛇头.她的目光碰上谁,谁就会立即变成石头.勇士珀尔修斯,一手拿剑,一手持盾,以盾作镜,挡住了她的目光,砍下了她的头颅.     

学习“加速度减小的加速运动”的思维障碍及其对策

在高中的物理学习中,我们经常会遇到加速度减小而速度增大的运动,从高空有一小球自由下落,与直立的轻质弹簧发生碰撞,在小球到达平衡位置的过程中,由于小球所受的向下的重力不变,而向上的弹力逐渐增大,但小于重力,所以小球所受的合力方向向下,大小逐渐减小,因此,加速度减小,但运动速度逐渐增大,但许多学生错误地认为加速度减小,速度一定是减小的,在简谐运动中,弹簧振子回到平衡位置的运动过程,弹簧振子做的也是加速度减小的加速运动,再比如,汽车以恒定的功率起动过程中,所做的运动也是加速度减小的加速运动,这类运动相对于匀变速直线运动要复杂,学生学习这部分知识普遍感到困难,如果不能正确的理解和掌握加速度减小的加速运动,将直接影响对运动物体全过程的正确分析,也就无法处理和解决这一类问题,所以把加速度减小的加速运动作为一个专题进行全面而系统的学习,为解决这类问题打下基础是很有必要的.     

名胜古迹与物理知识

 游览名胜古迹,不仅可以饱尝山水风光的优美,人文古迹的绚丽,还可以从中学到不少的物理知识.园林中一些奇特的建筑,往往蕴藏着丰富的物理知识.这些建筑,常不以雄伟华丽取胜,而以奇引人.扬州个园的四季假山,其冬山的雪山墙,墙上开了24个大圆洞,游客到此,感到不可思议、如稍加分析,则可发现:圆洞迎风而设,似如音孔,能“招风透声”,墙后一条封闭的“深巷’,仿佛乐器音箱产生共鸣,北风劲吹,不仅白山假山和“冰裂”似的石板地面,构成隆冬的雪景,呼啸的风声,又增添了游客入冬的意境.     

原子荧光法测定刺五加不同部位中的砷、锑、汞、硒

采用微波消解处理样品,建立了氢化物发生-原子荧光法测定刺五加不同部位中的As, Sb, Hg, Se的分析方法。在最佳工作条件下,Se, Sb, Hg, Se的浓度与荧光强度均呈现良好的线性关系。砷的检出限为0.068 ng·mL-1,RSD为1.05%;锑的检出限为0.155 ng·mL-1,RSD为1.32%;汞的检出限为0.014 ng·mL-1,RSD为2.03%;硒的检出限为0.052 ng·mL-1,RSD为2.34%。并选用标准物质人发(GBW07601)对测定方法的准确度进行考察,该方法灵敏、快速准确。实验结果表明,刺五加不同部位中As, Sb, Hg, Se的含量有所差异。As, Hg和Se主要在叶中含量较高,锑在根中的含量高于其他部位。     

肢体语言在物理教学中的应用

肢体语言又称身体语言,是指借助于身体的各种动作,辅助或完全代替语言,藉以表情达意广义的肢体语言不仅只包含用四肢,还包含用面部表情和身体其他各个部位在内,来表达思想借助于肢体语言,能使教学生动,富有感染力,能提高学生的学习热情,并能消除教师和学生在课堂上的疲劳,使教与学产生双赢的效果;     

Ordering of diagnostic information in encoded medical images. Accuracy progression

A concept of diagnostic accuracy progression for embedded coding of medical images was presented. Implementation of JPEG2000 encoder with a modified PCRD optimization algorithm was realized and initially verified as a tool for accurate medical image streaming. Mean square error as a distortion measure was replaced by other numerical measures to revise quality progression according to diagnostic importance of successively encoded image information. A faster increment of image diagnostic importance during reconstruction of initial packets of code stream was reached. Modified Jasper code was initially tested on a set of mammograms containing clusters of microcalcifications and malignant masses, and other radiograms. Teleradiologic applications were considered as the first area of interests.     

Study on the quality assurance of diagnostic X-ray machines and assessment of the absorbed dose to patients

Radiation exposure and image quality in X-ray diagnostic radiology provide a clear understanding of the relationship between the radiation dose delivered to a patient and image quality in optimizing medical diagnostic radiology. Because a certain amount of radiation is unavoidably delivered to patients, this should be as low as reasonably achievable. Several X-ray diagnostic machines were used at different medical diagnostic centers in Egypt for studying the beam quality and the dose delivered to the patient. This article studies the factors affecting the beam quality, such as the kilo-volt peak (kVp), exposure time (mSc), tube current (mAs) and the absorbed dose in (μGy) for different examinations. The maximum absorbed dose measured per mAs was 594±239 and 12.5±3.7 μGy for the abdomen and the chest, respectively, while the absorbed dose at the elbow was 18±6 μGy, which was the minimum dose recorded. The compound and expanded uncertainties accompanying these measurements were 4±0.35% and 8±0.7%, respectively. The measurements were done through quality control tests as acceptance procedures.     

Laser spectroscopy applied to energy,environmental and medical research

Through the development of powerful laser spectroscopy techniques new means for advanced diagnostics and sample analysis have emerged. Applications of laser spectroscopy in the fields of energy, environmental and medical research are discussed. Emphasis is placed on non-intrusive diagnostic techniques for studying combustion processes, for remote monitoring of atmospheric pollutants and for industrial and medical applications of laser-induced fluorescence. Selected examples from work performed at the Lund Institute of Technology are used as illustrations, and references to books, reviews and selected papers are given.     

高场超导MRI系统铁磁屏蔽的几何优化

磁共振成像（MRI）系统是一种重要的医学影像诊断设备,它根据核磁共振原理对处于静磁场中的人体器官进行成像,具有清晰度高和任意层面成像等优点,在医学检查和诊断方面有着重要的作用,与低场MRI相比,高场MRI系统可提高质子的磁化率,增加图像的信噪比,缩短MRI信号采集时间,从而使脑功能成像的信号变化更为明显;但是较高的背景...     

Compression evaluation of surgery video recordings retaining diagnostic credibility (compression evaluation of surgery video)

Wider dissemination of medical digital video libraries is affected by two correlated factors, resource effective content compression that directly influences its diagnostic credibility. It has been proved that it is possible to meet these contradictory requirements halfway for long-lasting and low motion surgery recordings at compression ratios close to 100 (bronchoscopic procedures were a case study investigated). As the main supporting assumption, it has been accepted that the content can be compressed as far as clinicians are not able to sense a loss of video diagnostic fidelity (a visually lossless compression). Different market codecs were inspected by means of the combined subjective and objective tests toward their usability in medical video libraries. Subjective tests involved a panel of clinicians who had to classify compressed bronchoscopic video content according to its quality under the bubble sort algorithm. For objective tests, two metrics (hybrid vector measure and hosaka Plots) were calculated frame by frame and averaged over a whole sequence.     

Use of a light-integrating sphere in low-intensity laser therapy

A method for applying the photometric(light-integrating) sphere to solve medical problems of laser therapy is proposed. In contrast to the currently commonly used method of intravenous laser irradiation of blood, this method is noninvasive. An additional advantage of the method is possibility of obtaining diagnostic data on the dynamic response of the organism to physiological stress.     

Acoustic Doppler shifts in medicine

This is a brief discourse on the history of the uses of acoustic Doppler frequency shifts in modern medicine. The Doppler effect and the Doppler equation are discussed. The technological developments over the last half century are covered, as well as their applications in diagnostic medical sonography. A limited discussion of the pathologies that may be diagnosed using the Doppler effect is also presented.     

Some experimental data for the design of acoustic arrays

The frequency spectra of resonant vibration of a PZT4 piezoelectric plate was observed, for width-to-thickness ratios ranging from 0·3 to 4·0. The results give useful information for the design of line arrays applicable, for example, to medical diagnostic sonars. The effect of backing and impedance matching on PZT4 ceramic slabs was also studied experimentally.     

Diagnostic Application of Fluorescence Spectroscopy in Oncology Field: Hopes and Challenges

Abstract

Cancer is one of the big killers of world population. The majority of cancers are diagnosed at a late stage, making a cure almost impossible. Fluorescence spectroscopy is an emerging diagnostic tool for various medical diseases including premalignant and malignant lesions. Fluorescence spectroscopy is a noninvasive technique and has been applied successfully for the diagnosis of multisystem cancers with high sensitivity and specificity. Fluorescence spectroscopy minimizes the need for repetitive biopsy, which is routine practice for cancer patient follow-up. But there are many aspects of this new diagnostic technique that should be discussed in future research to overcome limitations and challenges faced by this technique for diagnosis of cancers.     

Breast cancer diagnostics by Raman spectroscopy

This paper presents new results for the normal, malignant and benign tissues by Raman spectroscopy. To the best of our knowledge, this is one of the most statistically reliable research (321 spectra from 44 patients) on Raman spectroscopy-based diagnosis of breast cancers among the world's women population. The paper demonstrates that Raman spectroscopy is a powerful medical diagnostic tool with the key advantage in breast cancer research.