EUROPEAN PUBLIC PERCEPTIONS OF SCIENCE

In this paper we explore the relationships between public interestin, knowledge of, and attitudes towards science and technologyand the level of industrialization in 12 countries of the EuropeanCommunity. Using the 1989 Eurobarometer survey no 31 (N=11,678),we constructed four scales measuring interest, knowledge, generalattitudes to science, and support for EC funded science foreach of the 12 EC countries. We found that overall factual scientificknowledge correlates moderately positively with interest andattitudes to science. For example the Netherlands and GreatBritain have relatively high levels of knowledge, interest,and support for science in general. Spain and Greece have relativelylow levels of knowledge, interest, and support for science ingeneral. However, the simple correlation hides more complexrelationships. First, the variance within and across countriesof knowledge, attitudes and interest increases with nationallevels of knowledge. This indicates greater degrees of polarizationof both support and interest. Second, the data indicates a post-industrialismeffect: knowledge, interest in, and attitudes to science showa curvilinear relationship with levels of industrialization.The decline of interest in science and the less positive attitudesin highly developed countries requires further exploration.Third, we found, that the consistency of the knowledge and theattitude measures declines as the national level of knowledgeincreases. We suggest that this reflects a knowledge-ignoranceparadox and knowledge specialization among informed populations.Support for EC level science follows a different pattern. Wefound that France, Italy, and Spain show high levels of supportfor EC level science. This is not the case in Great Britainand Germany. The pattern suggests that attitudes towards ECscience are formed on the basis of national level scientificstrength: if the national science base is strong, EC scienceinitiatives find less support and vice versa. These findingsrepresent a first step towards a comparative assessment of publicunderstanding of science in EC countries.     

网络信息检索中利用the Staceys测度方法提高逻辑运算效率的思考

网络信息检索中,逻辑运算符AND连接检索词的顺序很大程度上会影响检索效率.论文首先分析、介绍了the Staceys测度方法在改善AND检索效率中发挥的作用,并在此基础上提出简化了的测度算法,最后通过实例说明其实现步骤.     

Teachers' perspectives on the challenges of teaching physical education in urban schools: the student emotional filter

The purpose of this study was to analyze how the challenges of urban schools influence physical education teachers' emotional understanding and connections with their students and the implications on their teaching. Sixty-one elementary physical educators from an urban school district in the midwestern U.S. were interviewed multiple times (N = 136) over 3 years using interpretive methodology. Teachers reported five unique challenges that significantly shaped their thinking about students and their careers, along with strategies they used to overcome or manage those challenges. The challenges were: (a) insufficient instructional resources, (b) implementing culturally relevant pedagogy, (c) dealing with community violence, (d) integrating more games in curricula, and (e) teaching in a culture of basketball. Implications centered on the guilt-inducing nature of urban teaching, developing an informed and realistic vision of urban physical education, and the role of teacher preparation and professional development.     

Climate control through ionization

This paper summarizes some of the experimental evidence of the apparent biological effects produced by atmospheric ionization. Thermionic ion sources are discussed and the results of experimental determinations of their characteristics are presented.     

Secondary electron emission from oxide-coated cathodes

The secondary electron emission from alkaline-earth oxide-coated cathodes has been investigated under both continuous and pulsed bombardment. Various factors affecting the yield, such as dependence upon primary voltage, collecting voltage, temperature, time, and angle of incidence, are noted, and the present state of the theory is discussed.Experiments have been performed with three types of apparatus. Yield vs. Energy data reveal values of δ of 4–7 at room temperature, with a more or less flat maximum at approximately 1,000 volts primary energy.The yield increases with temperature in an exponential manner, and plots of log Δδ (i.e. δ_K° ? δ_300°K) vs. 1/T give straight lines. Values of Q₁ between 0.9 – 1.5 eV. are generally indicated, and from extrapolation of these curves, yields exceeding 100 at 850° C. are deduced. The secondary emission depends upon the degree of activation, and increases with enhancement of the thermionic emission characteristics. Short-time effects such as growth or decay of secondary current after the onset of primary bombardment or persistence after the cessation of bombardment have not been observed, and values of yield obtained by pulsed methods are in accord with those obtained under D.C. conditions. Tail phenomena reported by J. B. Johnson and interpreted as “enhanced thermionic emission” from oxidecoated cathodes become manifest only under experimental conditions characterized by certain space-charge effects, and have been effectively simulated by bombarding a tantalum target adjacent to an electron-emitting tungsten filament. Various measurements of the energy distribution of secondary electrons as a function of primary voltage and temperature have been obtained. It was observed that the average energy of the secondary electrons decreases with temperature at a rate which more than compensates for the increase in the number of secondaries emitted per incident primary. The mechanism of the observed dependence of yield upon temperature is not well understood. Various alternative explanations are discussed and, in the light of the present state of our knowledge, regarded as untenable.     

The relay oscillator and related devices

Several arrangements of relay, condenser, and battery can be made to oscillate dependably. The electrical properties of these oscillators, as well as of a number of derivative devices, are here outlined.