The Contribution of Large and Small Employers to Job Creation in Times of High and Low Unemployment

We document a negative correlation, at business cycle frequencies, between the net job creation rate of large employers and the level of aggregate unemployment that is much stronger than for small employers. The differential growth rate of employment between initially large and small employers has an unconditional correlation of —0.5 with the unemployment rate, and varies by about 5 percent over the business cycle. We exploit several datasets from the United States, Denmark, and France, both repeated cross sections and job flows with employer longitudinal information, spanning the last four decades and several business cycles. We discuss implications for theories of factor demand. (JEL D22, E23, E32, J23, L25)

Growth of the banana prawn, Penaeus merguiensis De Man, as estimated from tagging studies in the Gulf of Papua

To estimate the growth parameters of the banana prawn, P. merguiensis, a tag-recapture study, using vinyl streamer tags (Floy FTSL-731, was undertaken throughout the northern Gulf of Papua. Recapture data were analysed using Fabens' derivation of the von Bertalanffy growth curve. A differential growth rate was found between male and female banana prawns: L∞ and K values for males were 29.34 mm carapace length (C.L.) and 0.136 per week, and for females 35.34 mm C.L. and 0.117 per week, respectively. The assumptions applied in estimating the parameters by the Fabens method were not invalidated. These prawns were shown to have a smaller maximum size than banana prawns from the Gulf of Carpentaria, and it is proposed that two discrete populations exist.

Differential Growth Rate in the Tail of the Pacific Big Skate, Raja binoculata

Over a period of years the egg cases of Raja binoculata Girard were collected from waters in the Strait of Georgia, British Columbia, and measurements of the total body lengths and tail lengths were recorded. From these data an hypothesis was formulated suggesting that the relative growth rate of the tail to the growth of embryos is related to the mode of respiration utilized at a given time during development.The method of respiration employed by embryos of elasmobranchs follows a chronological sequence of integumentary, external gill filament, and spiracular–branchial respiration. To determine whether this hypothesis was tenable the data were subjected to a statistical analysis. A linear regression on the logarithms of the data was performed for caudal lengths below and above 8.5 cm. In each instance the probability that the resulting slope was not zero was Jess than 0.0001. Further, an analysis of covariance was performed that indicated that the two slopes were significantly different with a probability of less than 0.005.It would seem reasonable on the basis of the above analysis to assume that the tail length-respiration relation is a tenable hypothesis.

The growth-rings on herring scales

This note summarises the results of certain investigations on this subject carried out in the Laboratory of the Board of Agriculture and Fisheries. The researches of each author were carried out independently, and their full reports will be published in the Fisheries Investigation Series of Reports of the Board. The number of scales on Teleostean fish being roughly the same throughout life, it is reasonable to suppose that they follow in their individual growth the growth of the fish as a whole: that when the fish is growing fast the scales grow at a corresponding rate. This differential growth-rate is clearly shown on those scales which are marked with concentric striations, for in these cases the striæ appear closer together when growth is slack than they do when growth is vigorous.