Seafloor displacements observed after the Tohoku earthquake place large constraints on assessing the deformation process.

One of the important issues on the GPS‐acoustic (GPS‐A) observation for sea bottom positioning is how to address the horizontal heterogeneity of the sound speed in oceans. This study presents an analysis method of GPS‐A data in the presence of a sloping sound speed structure. By applying this method and revising the analysis scheme to make full use of existing data, we reevaluated the horizontal postseismic deformations occurring ~1.5–5 years after the 2011 Tohoku earthquake. The revised horizontal movements have more uniform directions and rates between neighboring sites, suggesting enhancement of the array positioning accuracy. The revised displacement rate of the site on the incoming Pacific plate, located ~100 km northeast of the main rupture zone, was decreased significantly; it was only slightly, by 1.4 cm/year larger than the global motion of the Pacific plate, suggesting a relatively small effect of viscoelastic relaxation. The horizontal movements of the near‐trench sites above the main rupture zone were generally landward and were significantly faster than the Pacific plate motion, indicating a viscoelastic relaxation of 5–10 cm/year. The distribution of the fast landward movements peaked near 38°N at an updip of the mainshock hypocenter and extended significantly farther to the north than to the south. This implies the existence of a secondary coseismic slip patch in the northern area in addition to a primary slip patch at ~38°N. The occurrence of episodic slow slip in early 2015 to the north of the main rupture zone was also verified from the GPS‐A analyses.

Numerous observations pertaining to the magnitude 9.0 2011 Tohoku-oki earthquake (offshore Japan) have led to new understanding of subduction zone earthquakes. By synthesizing published research results and our own findings, we explore what has been learned about fault behavior and Earth rheology from the observation and modeling of crustal deformation before, during, and after the earthquake. Before the earthquake, megathrust locking models based on land-based geodetic observations correctly outlined the along-strike location of the future rupture zone. Their incorrect definition of the locking pattern in the dip direction demonstrates the need to model the effects of interseismic viscoelastic stress relaxation and stress shadowing. The observation of decade-long accelerated slip downdip of the future rupture zone raises new questions on fault mechanics. During the earthquake, seafloor geodetic measurements revealed huge coseismic displacements (up to 31 m). Modeling of bathymetry difference before and after the earthquake suggests >60 m of coseismic slip of the most seaward 40 km of the fault in the main rupture area, with the slip peaking at the trench. Large differences in shallow slip between published rupture models are due mainly to the near absence of near-trench deformation measurements, but model simplifications in fault and seafloor geometry also bear large responsibility. After the earthquake, seafloor geodetic measurements provided unambiguous evidence for the dominance of viscoelastic relaxation in short-term postseismic deformation. There is little deep afterslip in the fault area where the decade-long pre-earthquake slip acceleration is observed. Investigating the physical processes responsible for the complementary spatial distribution of pre-slip and afterslip calls for new scientific research.

Various three-dimensional structures have been created on a nanometer scale using the self-assembly of DNA molecules. However, ordinary DNA structures breakdown readily because of their flexibility. In addition, it is difficult to control them by inputs from environments. Here, we construct robust and photocontrollable DNA capsules using azobenzenes. This provides a method to construct DNA structures that can survive higher temperatures and can be controlled with ultraviolet irradiation.

ObjectivesThe aim of this study was to investigate the effect of hyperglycaemia on oxidative stress markers and inflammatory and matrix gene expression within tendons of normal and diabetic rats and to give insights into the processes involved in tendinopathy.MethodsUsing tenocytes from normal Sprague-Dawley rats, cultured both in control and high glucose conditions, reactive oxygen species (ROS) production, cell proliferation, messenger RNA (mRNA) expression of NADPH oxidase (NOX) 1 and 4, interleukin-6 (IL-6), matrix metalloproteinase (MMP)-2, tissue inhibitors of matrix metalloproteinase (TIMP)-1 and -2 and type I and III collagens were determined after 48 and 72 hours in vitro. In an in vivo study, using diabetic rats and controls, NOX1 and 4 expressions in Achilles tendon were also determined.ResultsIn tenocyte cultures grown under high glucose conditions, gene expressions of NOX1, MMP-2, TIMP-1 and -2 after 48 and 72 hours, NOX4 after 48 hours and IL-6, type III collagen and TIMP-2 after 72 hours were significantly higher than those in control cultures grown under control glucose conditions. Type I collagen expression was significantly lower after 72 hours. ROS accumulation was significantly higher after 48 hours, and cell proliferation after 48 and 72 hours was significantly lower in high glucose than in control glucose conditions. In the diabetic rat model, NOX1 expression within the Achilles tendon was also significantly increased.ConclusionThis study suggests that high glucose conditions upregulate the expression of mRNA for NOX1 and IL-6 and the production of ROS. Moreover, high glucose conditions induce an abnormal tendon matrix expression pattern of type I collagen and a decrease in the proliferation of rat tenocytes.Cite this article: Y. Ueda, A. Inui, Y. Mifune, R. Sakata, T. Muto, Y. Harada, F. Takase, T. Kataoka, T. Kokubu, R. Kuroda. The effects of high glucose condition on rat tenocytes in vitro and rat Achilles tendon in vivo. Bone Joint Res 2018;7:362–372. DOI: 10.1302/2046-3758.75.BJR-2017-0126.R2