Habitat Choice and Female Preference in a Polymorphic Stickleback Population

Background: A small pond, c. 90 years old, near Bern, Switzerland contains a population of threespine stickleback (Gasterosteus aculeatus) with two distinct male phenotypes. Males of one type are large, and red, and nest in the shallow littoral zone. The males of the other are small and orange, and nest offshore at slightly greater depth. The females in this population are phenotypically highly variable but cannot easily be assigned to either male type. Question: Is the existence of two sympatric male morphs maintained by substrate-associated male nest site choice and facilitated by female mate preferences? Organisms: Male stickleback caught individually at their breeding sites. Females caught with minnow traps. Methods: In experimental tanks, we simulated the slope and substrate of the two nesting habitats. We then placed individual males in a tank and observed in which habitat the male would build his nest. In a simultaneous two-stimulus choice design, we gave females the choice between a large, red male and a small, orange one. We measured female morphology and used linear mixed effect models to determine whether female preference correlated with female morphology. Results: Both red and orange males preferred nesting in the habitat that simulated the slightly deeper offshore condition. This is the habitat occupied by the small, orange males in the pond itself. The proportion of females that chose a small orange male was similar to that which chose a large red male. Several aspects of female phenotype correlated with the male type that a female preferred.

Large heterogeneities in comet 67P as revealed by active pits from sinkhole collapse

Pits have been observed on many cometary nuclei mapped by spacecraft(1-4). It has been argued that cometary pits are a signature of endogenic activity, rather than impact craters such as those on planetary and asteroid surfaces. Impact experiments(5,6) andmodels(7,8) cannot reproduce the shapes of most of the observed cometary pits, and the predicted collision rates imply that few of the pits are related to impacts(8,9). Alternative mechanisms like explosive activity(10) have been suggested, but the driving process remains unknown. Here we report that pits on comet 67P/Churyumov-Gerasimenko are active, and probably created by a sinkhole process, possibly accompanied by outbursts. We argue that after formation, pits expand slowly in diameter, owing to sublimation-driven retreat of the walls. Therefore, pits characterize how eroded the surface is: a fresh cometary surface will have a ragged structure with many pits, while an evolved surface will look smoother. The size and spatial distribution of pits imply that large heterogeneities exist in the physical, structural or compositional properties of the first few hundred metres below the current nucleus surface.

Medication double-checking procedures in clinical practice: a cross-sectional survey of oncology nurses' experiences.

BACKGROUND Double-checking is widely recommended as an essential method to prevent medication errors. However, prior research has shown that the concept of double-checking is not clearly defined, and that little is known about actual practice in oncology, for example, what kind of checking procedures are applied. OBJECTIVE To study the practice of different double-checking procedures in chemotherapy administration and to explore nurses' experiences, for example, how often they actually find errors using a certain procedure. General evaluations regarding double-checking, for example, frequency of interruptions during and caused by a check, or what is regarded as its essential feature was assessed. METHODS In a cross-sectional survey, qualified nurses working in oncology departments of 3 hospitals were asked to rate 5 different scenarios of double-checking procedures regarding dimensions such as frequency of use in practice and appropriateness to prevent medication errors; they were also asked general questions about double-checking. RESULTS Overall, 274 nurses (70% response rate) participated in the survey. The procedure of jointly double-checking (read-read back) was most commonly used (69% of respondents) and rated as very appropriate to prevent medication errors. Jointly checking medication was seen as the essential characteristic of double-checking-more frequently than 'carrying out checks independently' (54% vs 24%). Most nurses (78%) found the frequency of double-checking in their department appropriate. Being interrupted in one's own current activity for supporting a double-check was reported to occur frequently. Regression analysis revealed a strong preference towards checks that are currently implemented at the responders' workplace. CONCLUSIONS Double-checking is well regarded by oncology nurses as a procedure to help prevent errors, with jointly checking being used most frequently. Our results show that the notion of independent checking needs to be transferred more actively into clinical practice. The high frequency of reported interruptions during and caused by double-checks is of concern.

Novel antennal lobe substructures revealed in the small hive beetle Aethina tumida

The small hive beetle, Aethina tumida, is an emerging pest of social bee colonies. A. tumida shows a specialized life style for which olfaction seems to play a crucial role. To better understand the olfactory system of the beetle, we used immunohistochemistry and 3-D reconstruction to analyze brain structures, especially the paired antennal lobes (AL), which represent the first integration centers for odor information in the insect brain. The basic neuroarchitecture of the A. tumida brain compares well to the typical beetle and insect brain. In comparison to other insects, the AL are relatively large in relationship to other brain areas, suggesting that olfaction is of major importance for the beetle. The AL of both sexes contain about 70 olfactory glomeruli with no obvious size differences of the glomeruli between sexes. Similar to all other insects including beetles, immunostaining with an antiserum against serotonin revealed a large cell that projects from one AL to the contralateral AL to densely innervate all glomeruli. Immunostaining with an antiserum against tachykinin-related peptides (TKRP) revealed hitherto unknown structures in the AL. Small TKRP-immunoreactive spherical substructures are in both sexes evenly distributed within all glomeruli. The source for these immunoreactive islets is very likely a group of about 80 local AL interneurons. We offer two hypotheses on the function of such structures.