The development and the present state of the disk instability model for outbursts of dwarf nova are reviewed. Two intrinsic instabilities are known in dwarf nova accretion disks, i.e., the thermal instability and the tidal instability. The thermal-tidal instability model (abbreviated the TTI model) that combines these two intrinsic instabilities was first proposed in 1989 by Osaki to explain the superoutburst phenomenon of SU UMa stars. In this paper a complete account of the TTI model is presented. We first explain the basic concept of the model and how it works for the superoutburst phenomenon. We then discuss recent refinements of the model, in particular on the start and the end of superoutbursts, by which we are now able to explain wide varieties in superoutburst light curves of different stars and of different superoutbursts within one and the same star. We also discuss some exceptional cases that apparently seem to contradict the theory, such as the 1985 superoutburst of U Gem itself. It is argued that the TTI model can after all explain most of the observed phenomena related to superoutbursts and superhumps in dwarf novae.
Middle atmosphere research was found to be important, for the first time in the 1970s, with an information on possible atmosphere damage caused by human activity. International endeavors organized and carried out the Middle Atmosphere Program (MAP in 1982-1985). It was essential to understand dynamics of the middle atmosphere in MAP. In the early 1980s atmospheric gravity waves were found to play an important role in dynamics in the mesosphere, the upper part of the middle atmosphere. It was a good coincidence that atmosphere radars were found to be powerful for observing gravity waves. The MU radar of Kyoto University was constructed just on time in 1984. The facility, the best in the world for middle atmosphere observation, has been open for visiting scientists, domestic and abroad, even now, producing many excellent works. Of these works, this paper intends to review some important works done mainly by our Kyoto University radar group together with the basic knowledge of gravity waves.
Animal cells have the intrinsic ability to adhere to each other and to form multicellular structures. Classic studies suggested that cells have divalent cation-dependent mechanisms for holding themselves together. Cadherins were identified as Ca2+-sensitive cell surface molecules; and extensive studies revealed that this family of molecules plays critical roles in cell-to-cell adhesion and tissue organization, and even in synapse formation. Further studies showed that molecules belonging to the cadherin superfamily have more diverse functions, such as those to regulate planar cell polarity. Thus, we have been able to disclose parts of the molecular mechanisms of how animal cells can assemble and organize themselves into complex multicellular structures.
A new orthocerid cephalopod species, Mooreoceras sibumasuense sp. nov., is described from the lowest part of the Chuping Formation in Bukit Tungku Lembu of the Perlis State, northwestern Peninsular Malaysia. The holotype of the species occurs in argillaceous limestone that is most likely late Kungurian (late Early Permian) in age and was deposited under cool-temperate water conditions on the Sibumasu Terrane of the eastern Cimmerian Continent. Most Permian species of Mooreoceras appear to be palaeobiogeographically confined to cool to cool-temperate palaeoclimate zones of the Australian Gondwana to Sibumasu region. Mooreoceras sibumasuense sp. nov. belongs to a group that probably survived due to isolation from high predatory stress in tropical to temperate seas.
In earlier publications, I have discussed that transcription of the majority of archaeal genes could be regulated by a single type of factors, i.e. homologues of E. coli Lrp and AsnC, now referred to as feast/famine regulatory proteins (FFRPs). Also I have noted that the 13 bp nucleotide sequences recognized by dimers of various FFRPs are in the same arrangement, here referred to as 5-3-5. In the present study it is shown that the above descriptions also apply to the archaeal transcription factors that have been experimentally identified by other groups since then. In promoters regulated by transcription factors, Phr and TrmB, 13 bp elements in the 5-3-5 arrangement are identified. The amino acid sequences of the two proteins resemble those of known FFRPs at positions important for forming 3D structures of a standard (i.e. full length) FFRP. The same is observed with the amino acid sequences of a transcription factor, GvpE, and its modulator GvpD at its N-terminus. Regulation of promoters by Gvps E and D is explained well by assuming that two types of 13 bp elements in the 5-3-5 arrangement are recognized, respectively, by homo-dimers of GvpE and hetero-dimers of Gvps E and D. Another transcription factor, MDR1, like Lrs14, has a DBD of the FFRP type, but lacks the standard assembly domain: an N-demi FFRP. Including another transcription factor, NrpR, characteristics common with known FFRPs are found for all the transcription factors analyzed, consistently with my earlier arguments.