Interaction of a vortex ring with the free surface of ideal fluid

The interaction of a small vortex ring with the free surface of a perfect fluid is considered. In the frame of the point ring approximation the asymptotic expression for the Fourier-components of radiated surface waves is obtained in the case when the vortex ring comes from infinity and has both horizontal and vertical components of the velocity. The non-conservative corrections to the equations of motion of the ring, due to Cherenkov radiation, are derived.Comment: LaTeX, 15 pages, 1 eps figur

Noncommutative solitons on Kahler manifolds

We construct a new class of scalar noncommutative multi-solitons on an arbitrary Kahler manifold by using Berezin's geometric approach to quantization and its generalization to deformation quantization. We analyze the stability condition which arises from the leading 1/hbar correction to the soliton energy and for homogeneous Kahler manifolds obtain that the stable solitons are given in terms of generalized coherent states. We apply this general formalism to a number of examples, which include the sphere, hyperbolic plane, torus and general symmetric bounded domains. As a general feature we notice that on homogeneous manifolds of positive curvature, solitons tend to attract each other, while if the curvature is negative they will repel each other. Applications of these results are discussed.Comment: 26 pages, 3 figures, harvmac; references adde

A global phylogeny of butterflies reveals their evolutionary history, ancestral hosts and biogeographic origins

Butterflies are a diverse and charismatic insect group that are thought to have evolved with plants and dispersed throughout the world in response to key geological events. However, these hypotheses have not been extensively tested because a comprehensive phylogenetic framework and datasets for butterfly larval hosts and global distributions are lacking. We sequenced 391 genes from nearly 2,300 butterfly species, sampled from 90 countries and 28 specimen collections, to reconstruct a new phylogenomic tree of butterflies representing 92% of all genera. Our phylogeny has strong support for nearly all nodes and demonstrates that at least 36 butterfly tribes require reclassification. Divergence time analyses imply an origin similar to 100 million years ago for butterflies and indicate that all but one family were present before the K/Pg extinction event. We aggregated larval host datasets and global distribution records and found that butterflies are likely to have first fed on Fabaceae and originated in what is now the Americas. Soon after the Cretaceous Thermal Maximum, butterflies crossed Beringia and diversified in the Palaeotropics. Our results also reveal that most butterfly species are specialists that feed on only one larval host plant family. However, generalist butterflies that consume two or more plant families usually feed on closely related plants

FIGURE 5 in A New Species of the Graphium (Pazala) mandarinus Group from Central Vietnam (Lepidoptera: Papilionidae)

FIGURE 5. Female genitalia of Graphium (Pazala) wenlingae Hu, Cotton & Monastyrskii sp. nov. from Tay Giang, Quang Nam, C. Vietnam; lateral view above, ventral view below; scale bar = 1.0 mm

FIGURE 7 in A New Species of the Graphium (Pazala) mandarinus Group from Central Vietnam (Lepidoptera: Papilionidae)

FIGURE 7. Distribution map of the Graphium (Pazala) mandarinus group, with the distribution of G. (P.) wenlingae sp. nov. highlighted in a red box

FIGURE 4 in A New Species of the Graphium (Pazala) mandarinus Group from Central Vietnam (Lepidoptera: Papilionidae)

FIGURE 4. Male genitalia of Graphium (Pazala) wenlingae Hu, Cotton & Monastyrskii sp. nov. from Ngoc Linh, Kon Tum, C. Vietnam; scale bar = 1.0 mm. All: genitalia as a whole, R.: lateral view of ring, TSU: dorsal view of tegumen, socii, and uncus, V. right valve, Ae.: lateral view of aedeagus, Ju.: ventral view of juxta