Differential Growth Effects Research Articles

A note on the real exchange rate, differential productivity growth and protectionism in gold standard germany, 1878–1913

note analyses the effects of differential productivity growth in the traded and non-traded goods sectors and of protectionism on the real exchange rate of Germany during the gold standard. Large deviations of the German real exchange rate occurred, despite the relatively open trading system and the high and increasing degree of commercial integration of Germany with the main gold standard countries. In Section II Balassa's [1964] model, which explains long-run deviations of the exchange rate from purchasing power parity on the basis of differential productivity growth between the traded and the non-traded goods sector, has been modified to take into account the existence of tariffs. In Section III empirical tests of the model are presented. They show that both differential productivity growth and changes in the degree of protectionism were important in* explaining the behaviour of the real exchange rate. Two appendices are attached to the note. Appendix I complements the main analysis of the note by measuring the effect of changes in the degree of protectionism and in the real exchange rate on the German trade balance. Appendix II contains a description of the sources of the data used.

Competitive interactions amongst four species of Glomus on maize and onion

Maize and onion plants were infected with four species of Glomus in all fifteen possible combinations. Growth of maize was enhanced similarly in all treatments whereas onion plants showed differential growth effects. Inocula containing more than one endophyte gave more consistent results, although spore yields were lower, in mixed inocula compared with inocula of single species. G. clarum spored prolifically throughout the treatments. Maize plants produced three times the number of spores compared with onions. G. clarum was a good competitor and G. caledonium much less efficient. Mixed inocula are suggested for field inoculations.

Effects of Differential Growth and Mortality in the Seasonal Succession of Phytoplankton Populations in Lawrence Lake, Michigan

An investigation was made of factors controlling algal succession in a small, oligotro- phic lake during summer stratification. Phytoplankton population densities, growth rates, sedimen- tation losses, and mortality due to zooplankton grazing were measured weekly. Cyclotella michigan- iana was the dominant alga through the end of June, at which time Cyclotella comensis began to increase, becoming the dominant by August. In August, high grazing pressure caused the rapid declines of both C. michiganiana and C. comensis, which were followed by an increase of Sphaer- ocystis schroeteri. The combined effect of greater growth rates and lower loss rates of C. comensis resulted in its dominance over C. michiganiana. In contrast, the C. comensis-S. schroeteri succes- sion clearly resulted from differential mortality alone. It is likely that losses due to sedimentation and/or grazing are important in many lakes and that interspecific competition may be less important in actually controlling seasonal succession.

Influence of Polychlorinated Biphenyls (PCBs) on Growth of Freshwater Algae

The toxicity of PCBs (Aroclor 1242) to freshwater algae was analyzed. In two closely related species of Chlorella, one was found to be extremely resistant and the other sensitive. Chlamydomonas reinhardi strains showed temporary sensitivity, which was overcome after 3 days of culture. Results from abiotic preculture indicated that in all cases enzymatic degradation or adsorption of PCBs by cells were not mechanisms explaining the observed differential sensitivities. However, adsorption of PCBs to glass surfaces, coupled with apparent differential uptake properties of the algal species studied, was shown to be the cause of the differential growth effects of PCBs on freshwater algae.

Differential Rates of Change and Violence: France and Germany, 1820-1920

The guiding theory relating differential growth rates of social systems or subsystems to maladaptive behaviors and/or violent exchanges can be traced back in time at least to Malthus. Although it seems possible to identify at least four conditions that may tend to reduce the effects of differential growth, it is claimed that none of these conditions apply to the interaction and growth of France and Germany in 1820-1920. Since the violent exchanges occurred both in 1870-1871 and in 1914-1918 a clear difference in power-related growth rates is expected. The empirical data showed Germany (Prussia) vastly superior in the rate of growth of popula tion and energy produced, that France and Germany seemed to be about even in regard to scientific and technical information, and that France was only superior in the growth of space controlled during a part of the time studied. It is concluded that the theory has received support. Technology, its correlates and their rates of change may be said to be the central emphasis of this theory and many similar theories. Two other sets of violence or aggression theories are population density theories and the set of biological, psychological or social-psychological theories. Accept ing one of these three theory sets as having explanatory value does not imply rejection of the other sets.

Growth and Yield of Soybean Lines in Relation to Phosphorus Toxicity and Phosphorus, Potassium, and Calcium Requirements1

High rates of P in pot experiments with three nutrient variables, P, K, and Ca, at 5 levels in a twice‐replicated 2(2n)+2n+1 composite design resulted in combination of growth responses and P‐toxicity effects, threshold leaf contents for which are given. Significant growth and differential responses among soybean [Glycine max (L.) Merrill] lines culminated in large yield responses with maxima at 450 to 500 kg P/ha. Differential growth effects developing in favor of a certain line may change between the 7‐leafed stage and the end of flowering in favor of another line. Treatments leading to maximum growth at the 7‐leafed stage contained too much P to proceed to maximmn growth and yield at later stages.Further screening of soybean lines should be directed at maximum nodulation or growth responses and minimum P‐toxicity hazard.