Recognition of conspecific odours by laboratory rats (Rattus norvegicus) does not show context specificity.

Recognition of conspecific odours by laboratory rats (Rattus norvegicus) does not show context specificity

The quiet life hypothesis in banking : evidence from German savings banks

The "quiet life hypothesis (QLH)" posits that banks enjoy the advantages of market power in terms of foregone revenues or cost savings. We suggest a unified approach to measure competition and efficiency simultaneously to test this hypothesis. We estimate bank-specific Lerner indices as measures of competition and test if cost and profit efficiency are negatively related to market power in the case of German savings banks.We find that both market power and average revenues declined among these banks between 1996 and 2006. While we find clear evidence supporting the QLH, estimated effects of the QLH are small from an economical perspective

Positively curved GKM-manifolds

Let T be a torus of dimension at least k and M a T-manifold. M is a GKM_k-manifold if the action is equivariantly formal, has only isolated fixed points, and any k weights of the isotropy representation in the fixed points are linearly independent. In this paper we compute the cohomology rings with real and integer coefficients of GKM_3- and GKM_4-manifolds which admit invariant metrics of positive sectional curvature.Comment: 19 pages, 7 figures. Final version, to appear in IMR

Long-time dynamics of spontaneous parametric down-conversion and quantum limitations of conversion efficiency

We analyze the long-time quantum dynamics of degenerate parametric down-conversion from an initial sub-harmonic vacuum (spontaenous down-conversion). Standard linearization of the Heisenberg equations of motions fails in this case, since it is based on an expansion around an unstable classical solution and neglects pump depletion. Introducing a mean-field approximation we find a periodic exchange of energy between the pump and subharmonic mode goverened by an anharmonic pendulum equation. From this equation the optimum interaction time or crystal length for maximum conversion can be determined. A numerical integration of the 2-mode Schr"odinger equation using a dynamically optimized basis of displaced and squeezed number states verifies the characteristic times predicted by the mean-field approximation. In contrast to semiclassical and mean-field predictions it is found that quantum fluctuations of the pump mode lead to a substantial limitation of the efficiency of parametric down-conversion.Comment: 5 pages, 4 figure

Unequal Crossover Dynamics in Discrete and Continuous Time

We analyze a class of models for unequal crossover (UC) of sequences containing sections with repeated units that may differ in length. In these, the probability of an `imperfect' alignment, in which the shorter sequence has d units without a partner in the longer one, scales like q^d as compared to `perfect' alignments where all these copies are paired. The class is parameterized by this penalty factor q. An effectively infinite population size and thus deterministic dynamics is assumed. For the extreme cases q=0 and q=1, and any initial distribution whose moments satisfy certain conditions, we prove the convergence to one of the known fixed points, uniquely determined by the mean copy number, in both discrete and continuous time. For the intermediate parameter values, the existence of fixed points is shown.Comment: 25 pages, 1 figure; to appear in J. Math. Bio