确定主截面内非寻常光传播方向的一种方法

文中用费马原理给出了光沿主截面入射时,非寻常光在各向异性介质中的传播方向,证明了当光轴与法线之间夹角为φ时,入射光的入射角i与非寻常光之折射角θ之间的关系。     

Short Report： Cyclic patterns of incidence rate for skin malignant melanoma： association with heliogeophysical activity

Background: Our previous studies revealed cyclicity in the incidence rate of skin malignant melanoma (SMM; ICD9, Dx: 172) in the Czech Republic (period T=7.50～7.63 years), UK (T=11.00 years) and Bulgaria (T=12.20 years). Incidences com-pared with the sunspot index Rz (lag-period dT= 2, 4, 6, 10 or 12 years) have indicated that maximal rates are most likely to appear on descending slopes of the 11-year solar cycle, i.e., out of phase. We summarized and explored more deeply these cyclic variations and discussed their possible associations with heliogeophysical activity (HGA) components exhibiting similar cyclicity. Methods: Annual incidences of SMM from 5 countries (Czech Republic, UK, Bulgaria, USA and Canada) over various time spans during the years 1964～1992 were analyzed and their correlations with cyclic Rz (sunspot number) and aa (planetary geomagnetic activity) indices were summarized. Periodogram regression analysis with trigonometric approximation and phase-correlation analysis were applied. Results: Previous findings on SMM for the Czech Republic, UK and Bulgaria have been validated, and cyclic patterns have been revealed for USA (T=8.63 years, P<0.05) and Canada (Ontario, T=9.91 years, P<0.10). Also, various 'hypercycles' were established (T=45.5, 42.0, 48.25, 34.5 and 26.5 years, respectively) describing long-term cyclic incidence patterns. The association of SMM for USA and Canada with Rz (dT= 6 and 7 years, respectively) and aa (dT=-10 and 9 years, respectively) was described. Possible interactions of cyclic non-photic influences (UV irradiation, Schumann resonance signal, low-frequency geomagnetic fluctuations) with brain waves absorbance, neuronal calcium dynamics, neuro-endocrine axis modulation, melatonin/serotonin disbalance and skin neuro-immunity impairment as likely causal pathways in melanoma appearance, were also discussed. Conclusion: The above findings on cyclicity and temporal association of SMM with cyclic environmental factors could not only allow for better forecasting models but also lead to a better understanding of melanoma aetiology.     

Age,Physical Activity,Physical Fitness,Body Composition,and Incidence of Orthopedic Problems

Abstract

The incidence of orthopedic problems was examined in 5, 582 men and women who attended the Cooper Clinic in Dallas, Texas between 1974 and 1982. The effects of age, physical activity, physical fitness, and body mass index (EMI) on the occurrence of these problems were examined using a proportional hazards approach. The expected risk of orthopedic problems per person-year was 0.045 for men and 0.046 for women. For men, physical fitness, BMI, and physical activity were associated with orthopedic problems, while for women, physical activity was the main predictor. Age was not a factor for either gender. The effect of change in physical fitness, physical activity, and BMI was examined in a subset of 2, 325 persons with more than one visit to the clinic. For women, physical activity and a decrease in BMI were associated with orthopedic problems, while for men none of those factors were significant. Again, age was not a factor in either group. The absence of any age effect on the occurrence of problems suggests that with regard to orthopedic problems, moderate amounts of physical activity in generally healthy persons may be recommended without special consideration as to age.     

有疾病潜伏期的传染病动力学模型

从不考虑种群动力学因素和添加种群动力学因素两种情形出发,在双线性发生率、标准发生率和βNαSI/N(α位于0.03和0.07之间)发生率下,建立了有疾病潜伏期的等各种传染病动力学模型。     

The role of education in nineteenth‐century doctrines of political economy

Human Characteristics and School Learning. By B. S. Bloom. Pp. 284. New York. McGraw‐Hill, 1976. £8.20.

Child Language, Learning and Linguistics. By David Crystal. Pp. 106. London: Edward Arnold, 1976. £4.25. Paper £1.95.

Schools Council Working Paper No. 60: Examinations at 18+—The N and F Studies. Pp. 272. London: Evans/Methuen Educational, 1978. £4.50.

In and Out of School (The ROSLA Community Education Project). By R. White &; D. Brockington. London: RKP, 1978. 200pp. Hardback £4.50, Paperback £2.25.

County Grammar School: A History of Ludlow Grammar School Through Eight Centuries Against its Local Background. By David J. Lloyd, 1977.

Adolescence and Youth in Prospect. Edited by John P. Hill and Franz J. Monks. Pp. 216. IPC Science and Technology Press, Ltd., Guildford; 1977. £6.80.

Resource‐Based Learning. By N. Beswick. Pp.xiv+264. Heinemann, London, 1977. £6.50.

Instead of Education. Ways to help people do things better. By John Holt. Pp. 252. Penguin Books, 1977. 8op.

Philosophical foundations for the curriculum. By Allen Brent, pp. 233. London: George Allen and Unwin, 1978. £7.50 hardback, £3.50 paperback.

The Politics of Curriculum Change. By Tony Becher and Stuart Maclure. Pp. 192. London: Hutchinson, 1978, £2.95.

Power and the Curriculum: Issues in Curriculum Studies. Edited by Colin Richards. Pp. 170. Driffield: Nafferton Books. 1978. £2.95.

The Nineteenth Century Woman: Her Cultural and Physical World, Edited by Sara Delamont and Lorna Duffin. Pp. 213. London: Croom Helm 1978: £7.50.

The training of teachers in England and Wales 1800—1975. By H. C. Dent. Pp. viii, 163. London: Hodder and Stoughton, 1977. Paperback £2.35.

American Education: An Introduction to Social and Political Aspects. By Joel Spring. Pp. vi, 234. New York and London: Longman, 1978: £4.50.     

具有非线性传染率的SEIS传染病模型的定性分析

讨论了一类具有非线性传染率的SEIS流行病模型,当基本再生数R0<1时,无病平衡点全局渐近稳定;基本再生数R0>1时,地方平衡点全局渐近稳定.     

我校566名学生健康调查分析

本文通过调查发现我校学生中患病率以视力不良为最高,其次是龋齿、砂眼,应引起重视。     

评审指标的关联性分析与应用

在广东省自然科学基金立项评审指标的基础上，分析了科研评审的特点和一些指标约简方法的不足，运用关联性分析方法和极大不相关方法，对科研立项评审系统的评审指标体系进行关联性分析，提出了简化评价指标体系的关联性方法，从而为建立更合理的评审体系提供理论依据。与其它数据约简方法相比，这种方法直接源于评审数据，思路清晰，拟合结果表明了本约简算法合理、可靠性强。     

数学解题中反射原理的应用

介绍镜面成像原理(反射原理)，结合实例阐述物理中镜面成像原理解决数学问题的方法．进一步介绍镜面成像原理在求最大值和最小值问题中的应用。     

Epidemiology of injuries in First Division Spanish football

Abstract

The aim was to examine the injuries sustained by Spanish football players in the First Division and to compare injury-related variables in the context of both competition and training. The injury data were prospectively collected from 16 teams (427 players) using a specific web-based survey during the 2008/2009 season. A total of 1293 injuries were identified (145 were recurring injuries). The overall injury incidence was 5.65 injuries per 1000 h of exposure. Injuries were much more common during competition than during training (43.53 vs. 3.55 injuries per 1000 h of exposure, P < 0.05). Most of the injuries (89.6%) involved the lower extremities, and overuse (65.7%) was the main cause. Muscle and tendon injuries were the most common types of injury (53.8%) among the players. The incidence of training injuries was greater during the pre-season and tended to decrease throughout the season, while the incidence of competition injuries increased throughout the season (all P < 0.05). In conclusion, the results of this study suggest the need for injury prevention protocols in the First Division of the Spanish Football League to reduce the number of overuse injuries in the muscles and tendons in the lower extremities. In addition, special attention should be paid during the pre-season and the competitive phase II (the last four months of the season) in order to prevent training and competition injuries, respectively.