达芬奇效应:简便的数字视频

数字视频将引发人们与电子产品交互方式的变革。实现数字视频不但复杂,而且费时费钱。而这一切难题在达芬奇技术面前全部烟消云散。     

Design of bandstop filters by reactance transformation

The usual method for designing bandstop filters is the reactance transformation from a lowpass prototype. When the filter specifications do not satisfy geometrical symmetry, the choice of stopband central frequency constitutes an interesting problem. This letter shows that the mean square of the stopband edges is the stopband central frequency that leads to the lowest selectivity parameter of the prototype.     

Technological autonomy and three definitions of technology

In this essay I argue that one way to comprehend popular discourse about new technologies is to explore the meanings of the term technology . I develop the need to interrogate the meaning of technology by contrasting studies of technological discourse with studies of scientific discourse. I delineate three meanings of technology assumed in popular and academic discourse: technology-as-instrumentality, technology-as-industrialization, and technology-as-novelty. Finally, I examine the deployment of these definitions by the Clinton administration as it promulgates and defends its policies regarding the Internet. I conclude by reflecting on the significance of popular equivocation on the meaning of technology for understanding the ideology of technology.     

Simple Zeros of the Riemann Zeta-Function

Assuming the Riemann Hypothesis, Montgomery showed by meansof his pair correlation method that at least two-thirds of thezeros of Riemann's zeta-function are simple. Later he and Taylorimproved this to 67.25 percent and, more recently, Cheer andGoldston increased the percentage to 67.2753. Here we proveby a new method that if the Riemann and Generalized LindelöofHypotheses hold, then at least 70.3704 percent of the zerosare simple and at least 84.5679 percent are distinct. Our methoduses mean value estimates for various functions defined by Dirichletseries sampled at the zeros of the Riemann zeta-function. 1991Mathematics Subject Classification: 11M26.     

Existence and Uniqueness of Fixed Points for Markov Operators and Markov Processes

This paper concerns a Markov operator T on a space L₁, and aMarkov process P which defines a Markov operator on a spaceM of finite signed measures. For T, the paper presents necessaryand sufficient conditions for:

a the existence of invariant probabilitydensities (IPDs)

b the existence of strictly positive IPDs,and

c the existence and uniqueness of IPDs.

Similar resultson invariant probability measures for P are presented. The basicapproach is to pose a fixed-point problem as the problem ofsolving a certain linear equation in a suitable Banach space,and then obtain necessary and sufficient conditions for thisequation to have a solution. 1991 Mathematics Subject Classification:60J05, 47B65, 47N30.     

Using humorous programs as a vehicle for humorous commercials

Many programs and commercials use humor to entertain and persuade viewers. This research examines the effect of levels of humor in program context on commercials and the perceptions of the products they advertise. Effects of humor levels in the commercials themselves are examined, as are effects of gender on perception of humor and product image. Increased program humor was detrimental to recall of products advertised. Gender, however, interacted with program humor levels. Products were viewed less negatively by men when they were exposed to commercials in a more humorous program context. The type of humor may explain why this did not hold for women because humor of a crass or sexual nature holds lower appeal for females. An increased level of commercial humor was found to be beneficial to recall and purchase intention.     

库仑加线性位基态解析解

应用新发展的单一轨迹积分方法求解库仑加线性位的基态量子波函数,得到基态能量和波函数的一般解析表达式,并讨论了解的收敛性.应用此方法讨论了重夸克偶素系统.