Nucleation process in the Burridge-Knopoff model of earthquakes

Nucleation process of the one-dimensional Burridge-Knopoff model of earthquakes obeying the rate- and state-dependent friction law is studied both analytically and numerically. The properties of the nucleation dynamics, the nucleation lengths and the duration times are examined together with their continuum limits.Comment: Title changed, one figure (previous Fig.2) omitted, several references (new Refs.5-8,21,24-28) added, and two eqs. (new eqs.1,5) added. Text expanded considerably, especially the part explaining the relation of the model to the elastic continuum model. To appear in Europhys. Letter

PESI-MS for Diagnostic Cytology

Objectives: Cytology and histology are 2 indispensable diagnostic tools for cancer diagnosis, which are rapidly increasing in importance with aging populations. We applied mass spectrometry (MS) as a rapid approach for swiftly acquiring nonmorphological information of interested cells. Conventional MS, which primarily rely on promoting ionization by pre-applying a matrix to cells, has the drawback of time-consuming both on data acquisition and analysis. As an emerging method, probe electrospray ionization-MS (PESI-MS) with a dedicated probe is capable to pierce sample and measure specimen in small amounts, either liquid or solid, without the requirement for sample pretreatment. Furthermore, PESI-MS is timesaving compared to the conventional MS. Herein, we investigated the capability of PESI-MS to characterize the cell types derived from the respiratory tract of human tissues. Study Design: PESI-MS analyses with DPiMS-2020 were performed on various type of cultured cells including 5 lung squamous cell carcinomas, 5 lung adenocarcinomas, 5 small-cell carcinomas, 4 malignant mesotheliomas, and 2 normal controls. Results: Several characteristic peaks were detected at around m/z 200 and 800 that were common in all samples. As expected, partial least squares-discriminant analysis of PESI-MS data distinguished the cancer cell types from normal control cells. Moreover, distinct clusters divided squamous cell carcinoma from adenocarcinoma. Conclusion: PESI-MS presented a promising potential as a novel diagnostic modality for swiftly acquiring specific cytological information

Dynamics of earthquake nucleation process represented by the Burridge-Knopoff model

Dynamics of earthquake nucleation process is studied on the basis of the one-dimensional Burridge-Knopoff (BK) model obeying the rate- and state-dependent friction (RSF) law. We investigate the properties of the model at each stage of the nucleation process, including the quasi-static initial phase, the unstable acceleration phase and the high-speed rupture phase or a mainshock. Two kinds of nucleation lengths L_sc and L_c are identified and investigated. The nucleation length L_sc and the initial phase exist only for a weak frictional instability regime, while the nucleation length L_c and the acceleration phase exist for both weak and strong instability regimes. Both L_sc and L_c are found to be determined by the model parameters, the frictional weakening parameter and the elastic stiffness parameter, hardly dependent on the size of an ensuing mainshock. The sliding velocity is extremely slow in the initial phase up to L_sc, of order the pulling speed of the plate, while it reaches a detectable level at a certain stage of the acceleration phase. The continuum limits of the results are discussed. The continuum limit of the BK model lies in the weak frictional instability regime so that a mature homogeneous fault under the RSF law always accompanies the quasi-static nucleation process. Duration times of each stage of the nucleation process are examined. The relation to the elastic continuum model and implications to real seismicity are discussed.Comment: Title changed. Changes mainly in abstract and in section 1. To appear in European Physical Journal

Adaptation to climate change and conservation of biodiversity using green infrastructure

In recent years, we have experienced mega-flood disasters in Japan due to climate change. In the last century, we have been building disaster prevention infrastructure (artificial levees and dams, referred to as "grey infrastructure") to protect human lives and assets from floods, but these hard protective measures will not function against mega-floods. Moreover, in a drastically depopulating society such as that in Japan, farmland abandonment prevails, and it will be more difficult to maintain grey infrastructure with a limited tax income. In this study, we propose the introduction of green infrastructure (GI) as an adaptation strategy for climate change. If we can use abandoned farmlands as GI, they may function to reduce disaster risks and provide habitats for various organisms that are adapted to wetland environments. First, we present a conceptual framework for disaster prevention using a hybrid of GI and conventional grey infrastructure. In this combination, the fundamental GI, composed of forests and wetlands in the catchment (GI-1) and additional multilevel GIs such as flood control basins that function when floodwater exceeds the planning level (GI-2) are introduced. We evaluated the flood attenuation function (GI-1) of the Kushiro Wetland using a hydrological model and developed a methodology for selecting suitable locations of GI-2, considering flood risk, biodiversity and the distribution of abandoned farmlands, which represent social and economic costs. The results indicated that the Kushiro Wetland acts as a large natural reservoir that attenuates the hydrological peak discharge during floods and suitable locations for introducing GI-2 are concentrated in floodplain areas developing in the downstream reaches of large rivers. Finally, we discussed the network structure of GI-1 as a hub and GI-2 as a dispersal site for conservation of the Red-crowned Crane, one of the symbolic species of Japan

Comprehensive Characterization of Structural, Electrical, and Mechanical Properties of Carbon Nanotube Yarns Produced by Various Spinning Methods

A comprehensive characterization of various carbon nanotube (CNT) yarns provides insight for producing high-performance CNT yarns as well as a useful guide to select the proper yarn for a specific application. Herein we systematically investigate the correlations between the physical properties of six CNT yarns produced by three spinning methods, and their structures and the properties of the constituent CNTs. The electrical conductivity increases in all yarns regardless of the spinning method as the effective length of the constituent CNTs and the density of the yarns increase. On the other hand, the tensile strength shows a much stronger dependence on the packing density of the yarns than the CNT effective length, indicating the relative importance of the interfacial interaction. The contribution of each physical parameter to the yarn properties are quantitatively analyzed by partial least square regression

新生仔期におけるストレプトゾトシン投与は、標準食摂取下の4CSマウスにおいて、持続的な高血糖を伴わずに異なるサブタイプの肝細胞癌を急速に引き起こす

Although diabetes mellitus (DM) is a well-known risk factor for hepatocellular carcinoma (HCC), the underlying mechanisms have not yet to be defined. We previously reported that DIAR mice fed with standard murine diet developed type 1 diabetes and HCC at age of 16 weeks old with a neonatal streptozotocin treatment (n-STZ). Because DIAR mice did not manifest obesity nor develop steatohepatitis, hyperglycemia with streptozotocin trigger or streptozotocin alone might turn on the hepato-carcinogenesis. An insulin-recruitment to DIAR-nSTZ mice showed an increased frequency of HCC during the first 12 weeks of age, although the diabetic indications notably improved. To elucidate the role of hyperglycemia in hepato-carcinogenesis, we performed a head-to-head comparative study by using 4CS mice and DIAR mice with n-STZ treatment. Newborn 4CS mice and DIAR mice were divided into STZ treated group and control group. The blood glucose levels of DIAR-nSTZ mice increased at age of eight weeks, while that of 4CS-nSTZ mice were maintained in the normal range. At eight weeks old, three out of five DIAR-nSTZ mice (60%) and one out of ten 4CS-nSTZ mice (10%) developed multiple liver tumors. At age of 12 weeks old, all eight of DIAR-nSTZ mice (100%) and two of 10 4CS-nSTZ mice (20%) developed multiple liver tumors. At 16 weeks old, all animals of DIAR-nSTZ and 4CS-nSTZ mice occurred liver tumors. DIAR-nSTZ showed hyperglycemia and HCC, and 4CS-nSTZ developed HCC without hyperglycemia. These results were interpreted that the onset of HCC maybe not related to the presence or absence of hyperglycemia but nSTZ treatment. On the other hand, since the carcinogenesis of 4CS-nSTZ is delayed compared to DIAR-nSTZ, hyperglycemia may play a role in the progression of carcinogenesis. Histologically, the liver tumor appeared irregularly trabecular arrangements of hepatocytes with various degrees of nuclear atypia. By immunohistochemical analyses, all liver tumors showed positive staining of glutamine synthetase (GS), an established human HCC marker. The expression pattern of GS was divided into a strong diffuse pattern and weak patchy pattern, respectively. The liver tumor showing the weak GS-patchy pattern expressed biliary/stem markers, EpCAM, and SALL4, partially. Because 4CS-nSTZ mice did not show any metabolic complications such as gaining body weight or high blood glucose level, it is a unique animal model with a simple condition to investigate hepatic carcinogenesis by excluding other factors