Co-appearance of superconductivity and ferromagnetism in a Ca2_2RuO4_4 nanofilm crystal

By tuning the physical and chemical pressures of layered perovskite materials we can realize the quantum states of both superconductors and insulators. By reducing the thickness of a layered crystal to a nanometer level, a nanofilm crystal can provide novel quantum states that have not previously been found in bulk crystals. Here we report the realization of high-temperature superconductivity in Ca$_2$RuO$_4$ nanofilm single crystals. Ca$_2$RuO$_4$ thin film with the highest transition temperature $T_c$ (midpoint) of 64~K exhibits zero resistance in electric transport measurements. The superconducting critical current exhibited a logarithmic dependence on temperature and was enhanced by an external magnetic field. Magnetic measurements revealed a ferromagnetic transition at 180~K and diamagnetic magnetization due to superconductivity. Our results suggest the co-appearance of superconductivity and ferromagnetism in Ca$_2$RuO$_4$ nanofilm crystals. We also found that the induced bias current and the tuned film thickness caused a superconductor-insulator transition. The fabrication of micro-nanocrystals made of layered material enables us to discuss rich superconducting phenomena in ruthenates

Field experiments to test the use of the normalized-difference vegetation index for phenology detection

Some previous studies have detected the timing of leaf expansion and defoliation using the normalized-difference vegetation index (NDVI), but to examine tree phenology using satellite data, NDVI results should be confirmed using ground-truthing. We examined the relationship between NDVI and tree phenology during leaf expansion and defoliation by simultaneously observing the spectral reflectance of the canopy surface and canopy surface images in a cool-temperate deciduous broad-leaved forest. To define the timing of leaf expansion and defoliation using NDVI, the index should meet three criteria: (1) NDVI should exhibit a monotonous increase or decrease (monotonicity). (2) The relationship between NDVI and the forest canopy\u27s status should be unique (uniqueness). (3) The method is robust against the systematic noise (bias) (robustness). In the spring, NDVI values of 0.2–0.3 (relative values: 0.15–0.28) and 0.6–0.7 (relative values: 0.65–0.78) satisfied all three criteria. NDVI values of 0.6–0.7 can serve as potential criteria for detecting the timing of leaf expansion. In autumn, no NDVI values satisfied all three criteria. Thus, NDVI does not appear to be useful for detecting the timing of defoliation. For an area where evergreen vegetation or snow covers the forest floor in winter, our results suggest that previous uses of NDVI to identify the timing of leaf expansion and defoliation on the basis of the date of the maximum rate of growth or reduction of NDVI and the date with a value midway between the year\u27s maximum and minimum values are misleading

Experimental model of chronic pancreatitis, a review - Does it really exist?

Experimental model of pancreatitis is mandatory for elucidating the pathobiology of the disease and also to see the response of a novel treatment. In addition, the need for an animal model of chronic pancreatitis is further strengthened by the relative inaccessibility and paucity of the human pancreatitis tissue. Whereas various models of acute pancreatitis and also of exocrine pancreatic tumor have been described, chronic pancr-eatitis has not been consistently reproduced in experimental animals. Many researchers attempted to establish an experimental model of chronic pancreatitis either by partially obstructing the drainage of pancreatic secretion in dogs and cats or by feeding alcohol to dogs and rats with and without temporary occlusion of the biliopancreatic duct or by surgically inducing ischaemia in the pancreas of the dogs. But, none of these models is identical with human disease. A consistently reproducible model of human chronic pancr-eatitis probably does not exist. In this expanding era of molecular biology which promises us to enhance greatly our understanding of this disease, a right experimental model of chronic pancreatitis is still in progress.疾患の実験モデルの作成は,その疾患の病因,病態の解明,さらに治療法の開発のために重要である｡筆者らの一人は厚生省難治性膵疾患調査研究班の班員として,慢性膵炎の病態の解明や治療法の開発に関する研究を行っており,その研究の一環として,慢性膵炎の実験モデルの作成を現在行っている｡そこで,これまで報告されている慢性膵炎の実験モデルについて概要を報告した｡種々の動物や方法でヒト慢性膵炎に病因,病態,組織像が類似するモデルの作成が試みられてきたが,そのすべてが合致するような慢性膵炎モデルは確 立されてはいない｡近年の分子生物学的研究の進歩は著しく,実験モデルへの応用が種々なされている現在,より簡便で再現性のある慢性膵炎モデルの作成が望まれるところである