Wildlife species preferences differ among children in continental and island locations

SUMMARYEfforts to prioritize wildlife for conservation benefit from an understanding of public preferences for particular species, yet no studies have integrated species preferences with key attributes of the conservation landscape such as whether species occur on islands (where invasive exotics are the primary extinction threat) or continents (where land use change is the primary extinction threat). In this paper, we compare wildlife species preferences among children from a continental location (North Carolina, USA, n = 433) and an island location (Andros Island, The Bahamas, n = 197). Children on the island preferred feral domesticated species and different types of taxa than mainland children, perhaps due to the strongly divergent species richness between the regions (e.g. island children showed greater preferences for invertebrates, lizards and aquatic species). Boys preferred fish, birds and lizards more than girls, whereas girls preferred mammals. The fact that island children showed strong preferences for invasive species suggests challenges for conservation efforts on islands, where controlling invasive exotic species is often of paramount importance, but can conflict with cultural preferences for these same species.

Response to Larsen & Thorkildsen's comments onExtinction-corrected mean thickness and integrated width used in the program UMWEG98

Some additional comments are made concerning the asymptotic expressions for the primary-extinction factor for a perfect spherical crystal.

Extinction-corrected mean thickness and integral width used in the programUMWEG98

The kinematical upper limit of the extinction-corrected mean thickness as well as the corresponding integral width of the intensity profiles are estimated for spherical crystals. The new expression for the primary-extinction correction is compared with expressions given recently in the literature as well as with those widely used in crystal structure analysis.

Electrical Field Effects on Crystalline Perfection of MBA-NP Crystals by Mapping of Bragg-Surface Diffraction

ABSTRACTThe interaction of weak electrical field with the molecular dipole of the MBA-NP crystals is investigated. Such interaction affects the misorientation and size of the perfect diffracting regions of the crystal, which is monitored by mapping the Bragg-surface diffraction condition. This diffraction technique has also confirmed that the diffracting regions are large enough to allow primary extinction and the non-uniform mosaicity along the crystal surface.

Nonsymmetrical X-ray diffraction in a perfect rectangular t × l crystal. Extinction and absorption

A theoretical investigation of diffraction in a rectangular t\times l crystal for nonsymmetrical coplanar scattering has been undertaken. The asymmetry in the scattering geometry, measured by an angle \gamma, causes different weights for the mixed Laue–Bragg contributions to the integrated power. Primary extinction and ordinary absorption are only moderately affected when the value of the geometrical parameter \zeta = (t/l)\tan\theta_{oh} \,\lt\, 1, \theta_{oh} being the Bragg angle. For increasing values of \zeta and \gamma the surface integration set-up for the Laue and Bragg regions is extensively changed, leading to pronounced effects. Analytical results for the normal absorption factor are presented.

Direct phase determination and refinement in the electron crystallography of small structures

The use of electron diffraction intensity data for quantitative determination of crystal structures was largely pioneered by Vainshtein, Pinsker and their co-workers, as recently reviewed, and was shown to produce results consistent with more typical X-ray structure analyses. Despite these encouraging results for a number of representative inorganic and organic materials, it is accurate to say that the technique has not been widely accepted by the crystallographic community. This is probably because, in several of the early analyses, contemporary X-ray structure results were used to provide heavy atom positions, thus providing much of the crystallographic phase information. Since it is also known that correct phases, combined with even scrambled structure factor amplitudes, will lead to a Fourier map that appears to be ’correct’, it is commonly (but incorrectly) thought that no ab initio electron diffraction determinations have been carried out for previously unsolved structures. In addition, the very complexity of n-beam dynamical scattering theory compared to ’primary extinction’ corrections has dampened enthusiasm to continue this work.