Tokyo City University

Kuniyoshi I., Sato S., Nagaike I., Bao Y.

SATO Y., ITABASHI S., JIAO Y.

Sahare A., Sano K., Itoh K., Suemasa N., Tanaka T., Torita M., Takeoka R.

The use of dynamic centrifuge modelling has substantially risen over the years for investigating failure mechanisms, studying the physics-based mechanics of soil–structure systems, and validating numerical tools. Nevertheless, the primary issues associated with the use of servo-hydraulic actuators (presently the prevailing shaking table for a geotechnical centrifuge) are their exorbitant expense, intricate operation, and shaking control. This paper describes the development of a novel cylindrical cam shaker for the newly installed Mark III geotechnical centrifuge facility at Tokyo City University. The cylindrical cam mechanism is activated once the desired voltage is applied by way of the electrical slip rings. The rotation of the cylindrical cam is translated into the linear motion of the follower plate, which then moves the shaker linearly back and forth. A stepwise procedure is developed to determine the voltage required to drive the shaker and achieve the desired earthquake characteristics for a given payload mass and centrifugal acceleration. The performance of the shaker was systematically assessed through a series of dynamic centrifuge experiments at different centrifugal accelerations and payload masses. Finally, the excellent capabilities of the developed mechanical shaker in terms of the repeatability of the base motions were demonstrated using a model example.

Mori C., Sawahasi M., Miki N., Suyama S.

Yoneda S., Sawahash M., Nagata S., Suyama S.

SUNOUCHI H., KIHARA T., SUESHIGE Y., SAITO K., TAKAYANAGI H.

SUESHIGE Y., KIKUCHI A., TAKAYANAGI H., SUGIMACHI T., MIYACHI H.

FURUYA K., NIWA Y., SANO T.

IWATA F., SUESHIGE Y., TAKAYANAGI H.

KANO T., HAMAMOTO T.

Gale S.W., Li J., Suddee S., Traiperm P., Peter C.I., Buruwate T., Crain B.J., McCormick M.K., Whigham D.F., Musthofa A., Gogoi K., Ito K., Minamiya Y., Fukuda T., Landrein S., et. al.

IntroductionThe terrestrial orchid genus Nervilia is diagnosed by its hysteranthous pattern of emergence but is nested among leafless myco-heterotrophic lineages in the lower Epidendroideae. Comprising ca. 80 species distributed across Africa, Asia and Oceania, the genus remains poorly known and plagued by vague and overlapping species circumscriptions, especially within each of a series of taxonomically intractable species complexes. Prior small-scale, exploratory molecular phylogenetic analyses have revealed the existence of cryptic species, but little is otherwise understood of origin, the scale and timing of its biogeographic spread, or the palaeoclimatic factors that have shaped its ecology and given rise to contemporary patterns of occurrence.MethodsHere, we sample widely throughout the generic range, including 45 named taxa and multiple accessions referable to several widespread ‘macrospecies’, as well as material of equivocal identity and probable undescribed status, for the first time enabling an evaluation of taxonomic boundaries at both species and sectional level. Using nuclear (ITS) and plastid (matK, trnL-F) sequence data, we conduct phylogenetic (maximum parsimony and Bayesian inference) and ancestral area analysis to infer relationships and resolve probable origin and colonisation routes.ResultsThe genus is strongly supported as monophyletic, as are each of its three sections. However, the number of flowers in the inflorescence and other floral characters are poor indicators of sectional affinity. Dated ancestral area analysis supports an origin in Africa in the Early Oligocene, with spread eastwards to Asia occurring in the Late Miocene, plausibly via the Gomphotherium land bridge at a time when it supported woodland and savanna ecosystems.DiscussionTaxonomic radiation in Asia within the last 8 million years ties in with dramatic Himalayan-Tibetan Plateau uplift and associated intensification of the Asia monsoon. Multiple long-range migrations appear to have occurred thereafter, as the genus colonised Malesia and Oceania from the Pliocene onwards. The bulk of contemporary species diversity is relatively recent, potentially explaining the ubiquity of cryptic speciation, which leaves numerous species overlooked and unnamed. Widespread disjunct species pairs hint at high mobility across continents, extinction and a history of climate-induced vicariance. Persistent taxonomic challenges are highlighted.

Hamaya K., Okada T., Kawashima K., Naito T., Oki K., Kikuoka S., Wagatsuma Y., Yamada M., Sawano K.

SAKAI Y., IWAMOTO K., OMAE Y., MIKAMI T., AKIDUKI T., SAKAI K., MEYER-CONDE M., TAKAHASHI H.

Yoneda S., Sawahashi M., Nagata S., Suyama S.

Taufan A., Zaki S.A., Tuck N.W., Rijal H.B., Khalid W., Othman N.