Spatial orientation of social caterpillars is influenced by polarized light

Processionary caterpillars of Thaumetopoea pityocampa (in Europe) and Ochrogaster lunifer (in Australia) (Lepidoptera: Notodontidae) form single files of larvae crawling head-to-tail when moving to feeding and pupation sites. We investigated if the processions are guided by polarization vision. The heading orientation of processions could be manipulated with linear polarizing filters held above the leading caterpillar. Exposure to changes in the angle of polarization around the caterpillars resulted in corresponding changes in heading angles. Anatomical analysis indicated specializations for polarization vision of stemma I in both species. Stemma I has a rhabdom with orthogonal and aligned microvilli, and an opaque and rugged surface, which are optimizations for skylight polarization vision, similar to the dorsal rim of adult insects. Stemmata II-VI have a smooth and shiny surface and lobed rhabdoms with non-orthogonal and non-aligned microvilli; they are thus optimized for general vision with minimal polarization sensitivity. Behavioural and anatomical evidence reveal that polarized light cues are important for larval orientation and can be robustly detected with a simple visual system.

Hydrothermal Synthesis and Optical Properties of Ellipsoid-Like CeO2 Nanostructures with Rugged Surface and Many Pores

The almost monodisperse ellipsoid-like CeO2 nanostructures with rugged surface and many pores have been synthesized by a smart hydrothermal technique. Various techniques have been applied to investigate the CeO2 nanostructures, including XRD, SEM, XPS, Raman scattering, UV-vis and Photoluminescence (PL) spectra. The results showed that the ellipsoid-like CeO2 have a fluorite cubic structure and there are Ce3+ ions and oxygen vacancies existing in surface of samples. It is also found that there is a red-shifting in the band gap of the materials compared to bulk one, which is mainly attributed to the influences of the Ce3+ ions, oxygen vacancies and the morphology of the materials. The photoluminescence measurement indicated that the ellipsoid-like CeO2 samples exhibit excellent optical properties at room temperature, which can be reasonably explained for the influences of the concentration of oxygen vacancies and Ce3+ ions.

A New Method to Extract CSP Gather of Topography for Scattered Wave Imaging

The seismic method is one of the major geophysical tools to study the structure of the earth. The extraction of the common scatter point (CSP) gather is a critical step to accomplish the seismic imaging with a scattered wave. Conventionally, the CSP gather is obtained with the assumption that the earth surface is horizontal. However, errors are introduced to the final imaging result if the seismic traces obtained at the rugged surface are processed using the conventional method. Hence, we propose the method of the extraction of the CSP gather for the seismic data collected at the rugged surface. The proposed method is validated by two numerical examples and expected to reduce the effect of the topography on the scattered wave imaging.