02 日本人はるかな旅 －身体に刻された跡－

基調講

Descriptions of the dental remains of Homo floresiensis

Dental remains of Homo floresiensis excavated during 2002-2004 at Liang Bua, Flores, Indonesia, consist of one partial maxillary dentition, two nearly complete mandibular dentitions, and four isolated teeth. We present here morphological descriptions of all these specimens and report aspects of their dentition, occlusion, and oral health condition. This dental assemblage represents probably five but possibly four or six individuals. These different individuals share similar dental characteristics, supporting the view that the Liang Bua H. floresiensis assemblage represents a single population. We also reassess the previous claims for primitive and modern aspects of the H. floresiensis teeth. The previous studies reached conflicting conclusions: some researchers claim that these teeth are fully modern, whereas others highlight premolar and other morphologies that suggest their direct evolutionary link with the African earliest form of Homo or Australopithecus rather than with H. erectus. Neither of these views are supported. The H. floresiensis teeth exhibit a mosaic of primitive, derived, and unique characters, with the reported primitive aspects broadly comparable to the morphologies observed in H. erectus sensu lato. Although a more comprehensive comparative analysis is needed to fully illustrate dental morphological affinities of this dwarfed hominin species, we find no grounds for the hypothesis that H. floresiensis originated from the small-bodied, primitive hominins such as H. habilis sensu lato

Parallel Real-Time PCR on a Chip for Genetic Tug-of-War (gTOW) Method

A microchip-based real-time polymerase chain reaction (PCR) device has been developed for the genetic tug-of-war (gTOW) method that provides quantitative data for research on biorobustness and systems biology. The device was constructed of a silicon glass chip, a temperature controlling Peltier element, and a microscope. A parallel real-time amplification process of target genes on the plasmids and the housekeeping genes in a model eukaryote Saccharomyces cerevisiae were detected simultaneously, and the copy number of the target genes were estimated. The device provides unique quantitative data that can be used to augment understanding of the system-level properties of living cells

Development of Narrow Loop Joint for Precast Concrete Slabs with Fiber-Reinforced Mortar: Experimental Investigation of Material Properties and Flexural Behavior of Joint

In the replacement of the reinforced concrete slab in existing steel girder bridges, a loop joint is commonly used to join precast concrete slabs on site. However, a relatively wide joint is needed, and considerable time and effort are consumed to construct the joint due to the addition of transverse reinforcements to the joint on site. These disadvantages affect the progress of on-site construction and should be addressed, especially when this method is applied to highway bridges, where early traffic opening is necessary in many cases. This study proposes a narrow loop joint that has fiber-reinforced mortar without transverse reinforcements. Several material tests were conducted to determine a suitable material for the joint. A series of flexural loading tests of slabs was conducted to investigate the flexural behavior of the proposed loop joint with the selected material (polyvinyl alcohol (PVA) fibers). The results showed that the flexural capacity and deformation performance of the proposed joint with PVA fibers are equivalent to those of the conventional loop joint