A model for rhythmic and temperature-independent growth in ‘clock’ mutants of neurospora

The Q 10 for the frequency (number of bands per 24 hours) of the ‘clock’ mutant (strain CL11A) of Neurospora crassa over the range 20–30° C is close to 1.0. By contrast, that for the double mutant, ‘wrist watch’ (strain CL12a), is closer to 2 over this temperature range. Strain CL12a differs from ‘clock’ in other ways as well, including 1) decreased rate of linear extension and band size, 2) greater sensitivity of growth rate to high temperatures and, 3) masking of rhythmic growth below 15° C. The response to temperature of several colonial mutants and standard (‘wild-type’) strains was studied and it is shown that some strains are temperature-independent yet arhythmic. A temperature-compensation model is presented to explain the response of ‘clock’ mutants to temperature and it is concluded that they demonstrate a non-circadian free-running endogenous rhythm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43284/1/11046_2005_Article_BF02049924.pd

Return Migration and the 'Healthy Immigrant Effect'

According to the "healthy immigrant effect" (HIE), immigrants upon arrival are healthier than locally born residents. However, this health advantage is supposed to diminish or even disappear over a relatively short period and the immigrants' health status is converging to that of the natives. The causes for this gradient of immigrants' health are subject to an ongoing discussion and the underlying trajectories are not yet fully understood. This paper investigates whether return migration can serve as an additional explanation for the declining health of immigrants, and thus aims at shedding some light on the trajectories underlying the HIE. The data used are drawn from 13 waves of the German Socio-Economic Panel. Using a random-effects probit model, this analysis explores the factors influencing re-migration by means of a sample of 4,426 migrants. In line with the existing literature, the study shows that e.g. having spouse and children in the home country, or being non-working or jobless yield a higher return probability, whereas all factors associated with attachment to Germany (e.g. language fluency, German citizenship, house ownership) reduce the probability of re-migration. Additionally, the results indicate that men reporting poorer health ('good', 'satisfactory', 'poor' or 'bad') are significantly less likely to return home relative to male immigrants who describe their health as 'very good'. However, for women, the effects are adverse to that of men, and none of the health coefficients for women is significant. Hence - at least for men - re-migration can be seen as an additional explanation for the HIE