Use of the dart apparatus by the hermaphroditic land snail Polymita muscarum (Lea, 1834).

Many species of pulmonate land snails are equipped with one or more so-called "love darts". Even though the number and shape of these calcareous darts vary considerably between species, dart use has only been investigated in very few species. Here, we redescribe the mating behaviour of Polymita muscarum because previous reports did not include the use of the dart apparatus. Mating in this hermaphroditic land snail can be divided into three stages: courtship, copulation and post-copulatory activity. During courtship, full eversion of the genital atrium is reached, thus exposing the sensitive zone, genital lobes and dart apparatus. We observed that P. muscarum pushes the everted dart apparatus repeatedly onto different parts of the partner's body and does not lose its dart after stabbing. Dissected specimens had a single, slender dart with a round base, a broad corona and a circular cross-section. We propose that the morphology of P. muscarum's dart is consistent with the idea of simple darts needing to be stabbed more often in order to increase the transfer of mucus, which contains a biologically active substance (i.e. allohormone) that enhances the chances of paternity. Besides adding to the growing diversity in the use of love darts in land snails, these findings contribute to the understanding of the evolution of this peculiar reproductive act. © Koninklijke Brill NV 2007

Rethinking ‘top‐down’ and ‘bottom‐up’ roles of top and middle managers in organizational change: implications for employee support

In this study we integrate insights from ‘top‐down’ and ‘bottom‐up’ traditions in organizational change research to understand employees’ varying dispositions to support change. We distinguish between change initiation and change execution roles and identify four possible role configurations in which top managers (TMs) and middle managers (MMs) can feature in change. We contend that both TMs and MMs can play change initiation and/or change execution roles, TMs and MMs have different strengths and limitations for taking on different change roles, and their relative strengths and limitations are compounded or attenuated based on the specific configuration of change roles. We subsequently hypothesize employee support for change in relation to different TM‐MM change role configurations. Our findings show that change initiated by TMs does not engender above‐average level of employee support. However, change initiated by MMs engenders above‐average level of employee support, and even more so, if TMs handle the change execution

Neutron-capture gamma-ray study of levels in Ba135 and description of nuclear levels in the interacting-boson-fermion model

We have performed neutron-capture gamma-ray studies on natural and enriched targets of 134Ba in order to investigate the nuclear levels of 135Ba. The low-energy level spectra were compared with the calculations using the interacting-boson-fermion model (IBFM) and the cluster-vibration model. The level densities up to 5 MeV that are calculated within the IBFM are in accordance with the constant temperature Fermi gas model. From the spin distribution we have determined the corresponding spin cutoff parameter σ and compared it to the prediction from nuclear systematics