Osaka University

About: Osaka University is a education organization based out in Osaka, Japan. It is known for research contribution in the topics: Laser & Population. The organization has 83778 authors who have published 185669 publications receiving 5158122 citations. The organization is also known as: Ōsaka daigaku.

The amphioxus genome illuminates vertebrate origins and cephalochordate biology

Abstract: Cephalochordates, urochordates, and vertebrates evolved from a common ancestor over 520 million years ago To improve our understanding of chordate evolution and the origin of vertebrates, we intensively searched for particular genes, gene families, and conserved noncoding elements in the sequenced genome of the cephalochordate Branchiostoma floridae, commonly called amphioxus or lancelets Special attention was given to homeobox genes, opsin genes, genes involved in neural crest development, nuclear receptor genes, genes encoding components of the endocrine and immune systems, and conserved cis-regulatory enhancers The amphioxus genome contains a basic set of chordate genes involved in development and cell signaling, including a fifteenth Hox gene This set includes many genes that were co-opted in vertebrates for new roles in neural crest development and adaptive immunity However, where amphioxus has a single gene, vertebrates often have two, three, or four paralogs derived from two whole-genome duplication events In addition, several transcriptional enhancers are conserved between amphioxus and vertebrates--a very wide phylogenetic distance In contrast, urochordate genomes have lost many genes, including a diversity of homeobox families and genes involved in steroid hormone function The amphioxus genome also exhibits derived features, including duplications of opsins and genes proposed to function in innate immunity and endocrine systems Our results indicate that the amphioxus genome is elemental to an understanding of the biology and evolution of nonchordate deuterostomes, invertebrate chordates, and vertebrates

Electron – optical-phonon interaction in single and double heterostructures

Abstract: Electron--optical-phonon interactions are studied in single and double heterostructures. The Hamiltonian describing electron-phonon interactions is derived with use of orthonormal eigenmodes of phonons calculated in the dielectric continuum model. Effects of interactions are expressed in the form of an effective electron-electron interaction mediated by virtual exchange of phonons. It is given by the sum of products of coupling constants and form factors for different modes. The coupling constants correspond to the Fr\"ohlich coupling constant in bulk and the form factors describe effects of electron confinement. The resulting expression is convenient and useful in discussing relative importance of interface modes and bulklike confined modes and also in exploring the possibility of reduction of electron--optical-phonon interactions in heterostructures. It is applied to calculations of the polaron mobility and magnetophonon resonance spectra. The results clearly demonstrate roles of interface phonons.