From spatially indirect to momentum-space indirect exciton by in-plane magnetic field

In-plane magnetic field is found to change drastically the photoluminescence spectra and kinetics of interwell excitons in GaAs/AlGaAs coupled quantum wells. The effect is due to the in-plane magnetic field induced displacement of the interwell exciton dispersion in a momentum space, which results in the transition from the momentum-space direct exciton ground state to the momentum-space indirect exciton ground state. In-plane magnetic field is, therefore, an effective tool for the exciton dispersion engineering.Comment: 4 pages, 3 figure

The control of indirect effects of biomanipulation

Results from long-term investigations on biomanipulation show that indirect effects are at least as important as direct effects are for the stability of biomanipulation. Three types of indirect effects can be distinguished: (1) a change in quantity or quality of the resource base, (2) behavioural change of the prey, and (3) development of anti-predator traits. Although indirect effects of type (2), (e.g. a change in the pattern of vertical migration of zooplankton), and type (3), (e.g. development of helmets and neck teeth in Daphnia), are important mechanisms, the most essential indirect effects regarding biomanipulation belong to type (1). An example of the latter will be demonstrated: the complex of indirect effects of enhanced grazing by large herbivores on the phosphorus metabolism of the lake. It is concluded that control of the indirect effects is absolutely necessary to stabilize biomanipulation measures, but this is much more difficult than the control of direct effects and needs deeper insights into the structuring mechanisms of food webs. Proper management of fish stocks, in combination with the control of phosphorus load and/or the physical conditions, seems to be the most promising way of controlling the indirect effects of biomanipulation

Direct Versus Indirect Measurement of Digit Ratio (2D:4D): A Critical Review of the Literature and New Data

Digit ratio (2D:4D: the relative lengths of the second and fourth digits) is widely used as a correlate of prenatal sex steroids. There are two common methods of measuring 2D:4D, the direct method and the indirect method. The modern interest in 2D:4D began 16 years ago when finger lengths were measured directly, but many studies now report 2D:4D calculated from indirectly measured fingers from photocopies or scans. However, there are concerns about the accuracy of the latter in comparison to the former. The purpose of this article was twofold: to review these concerns and to add new data to the debate. Our review shows that in 2005, directional effects in indirect 2D:4D were reported such that direct 2D:4D > indirect 2D:4D. This finding was challenged by a 2006 report that direct 2D:4D was lower (not higher) than indirect 2D:4D for male right-hand 2D:4D. Two further studies from the same group have claimed that indirect 2D:4D may be lower, higher, or comparable to direct 2D:4D. More recent comparisons of direct 2D:4D versus indirect 2D:4D and a meta-analysis of Chinese studies have replicated the finding of direct 2D:4D > indirect 2D:4D. We considered an additional sample and found significant direct 2D:4D > indirect 2D:4D for three of four ratios. The overall literature is discussed within the context of standards of research (sample size) and publishing (clarity of report). It is concluded that direct 2D:4D does tend to be greater than indirect 2D:4D. Implications for comparative studies and other aspects of research in 2D:4D are discussed