G-jitter effects on half floating-zone convection in intermediate-frequency range

The g-jitter influence on thermocapillary convection and critical Marangoni number in a liquid bridge of half-floating rone was discussed in the low frequency range of 0.4 to 1.5 Hz in a previous paper. This paper extended the experiments to the intermediate frequency range of 2 to 18 Hz, which htrs often been recorded as vibration environment of spacecrafts. The experiment was completed on the deck of a vibration machine, which gave a periodical applied acceleration to simulate the effects of g-jitter. The experimental results in the intermediate frequency range are different from that in the low frequency range. The velocity field and the shape of the free surface have periodical fluctuations in response to g-jitter. The amplitude of the periodical varying part of the temperature response decreases obviously with increasing frequency of g-jitter and vanishes almost when the frequency of g-jitter is high enough. The critical Marangoni number is defined to describe the transition from a periodical convection in response to g-jitter to an oscillatory convection due to internal instability, and will increase with increasing g-jitter frequency. According to the spectral analysis, it can be found that the oscillatory part of temperature is a superposition of two harmonic waves if the Marangoni number is larger than a critical value.

Alfabetização na idade certa : garantir a aprendizagem no início do ensino fundamental

Consultoria Legislativa - Área XV - Educação, Cultura, Desporto, Ciência e Tecnologia.

Theory of local mode excitation in polyatomics by frequency-modulated lasers

that the Stokes-interaction relation is reasonable qualitatively but not correct

One possible way to promote the bond-selective chemical-reactions by frequency-modulated lasers

It is proposed in this paper that we can use frequency-modulated (FM) lasers to realize bond-selective chemical reactions or to raise the efficiency of molecular isotope separation. Examples are given for HF molecule and the C–H bond in some hydrocarbons.

A Fundamental Contradiction in Standard Rent Theory: A Case Study on Varian's "Intermediate Microeconomics"

In this paper, I examine Varian’s treatment of rent in his textbook on Microeconomics. I argue that he holds contradictory conceptions: sometimes rent is defined as surplus over cost whereas sometimes it is defined as cost, as the opportunity cost of fixed factors. I start by arguing that the distinction between fixed and variable factors is not the key for the definition of rent; ultimately, it is monopoly. Varian’s conception of rent is, essentially, Ricardo’s: rent is extraordinary profit turned rent. On the basis of a selfinconsistent notion of opportunity cost, Varian introduces the idea that rent is the opportunity cost of land, when what he actually defines is the opportunity cost of not renting the land. I also critically examine the related notion of “producer’s surplus”, and show that Varian’s treatment repeats the same contradiction as in rent.

A educação para a cidadania fiscal : ações do Programa Nacional de Educação Fiscal - PNEF no ensino fundamental e médio

Objetiva identificar os fatores que dificultam o avanço das propostas de educação para a cidadania fiscal apresentadas pelo Programa Nacional de Educação Fiscal(PNEF) para o ensino fundamental e médio e as possíveis razões que explicam esses dificultadores.