Rate Of Change In Size Research Articles

Farm Panels as a Source of Farm Management Data: The Cornell Producer Panel

LTHOUGH panels have been used in consumer research for a number of years, the use of a panel of producers or farmers as a source of farm management data or for studying changes on farms over time is a more recent development. Basically, a producer or farm panel is a group of farmers questioned and revisited over a period of time to obtain various types of information. Studies using the panel technique were initiated at the University of Minnesota [9] and Cornell University [2] in 1959. These panels were directed to analyzing changes over time in the quantity and characteristics of resources associated with changes in milk production on dairy farms and to projecting future changes. At Ohio State, panels have been used as a technique for obtaining input-output data [8]. The purpose of this paper is to describe and evaluate the Cornell Producer Panel. The sampling technique and cost of obtaining data are discussed. The usefulness of such a panel in determining rates of change in size and technology and in assessing farmer behavior is considered. The advantages of producer panels over other techniques and the future use of a panel of this type are indicated.

Size change in development and evolution

Phylogeny is a succession of ontogenies, and the two have been compared by considering them in terms of rates of size change. In development, the larger the organism, the slower its rate of size increase. In evolution, the rates of size change can be put into three distinct categories: fast, medium, and slow. The fast changes occur over short periods of time (1–10 thousand years) and are as likely to show size decrease as increase. The medium changes occur over longer time spans (5–20 million years) and are predominantly or entirely instances of size increase. The slow changes occur over the entire span of organic evolution and represent the maximum size attained in various phyla, which again show an over-all increase.For ontogeny, a decrease in rate of size change is correlated with an increase in complexity, an increase in the number of gene actions. For evolution, it is correlated with an increase in the number of genetic changes required of the genome by natural selection in fluctuating environments.

EFFECTS OF AGING UPON GERM CELLS AND UPON EARLY DEVELOPMENT

Aging eggs show progressive measurable morphologic and physiologic changes. Besides those described in Study II., there are a number particularly evident in later stages of aging eggs, such as agglutination and fusion of eggs, irregular cleavage, separation of the blastomeres and cytolysis.A. 1. The agglutination phenomenon occurred only in physiologically very deteriorated or "aged" eggs, as evidenced in part by the low per cent. of the jelly layer, inability to develop a fertilization membrane, a more viscous condition of the cytoplasm and cortical layer, and by numerous other tests. These are exactly the conditions that have been sought in the experimental agglutination of eggs.2. The onset of agglutination occurred at different ages for the eggs of different females, such variations being due to differences in physiologic condition of the eggs at the time of liberation from the parent. The more deteriorated the eggs at liberation the earlier the agglutination, and vice versa. Agglutination occurred in...