Observed variations in turbulent mixing efficiency in the deep ocean

Author Posting. © American Meteorological Society, 2018. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 48 (2018): 1815-1830, doi:10.1175/JPO-D-17-0275.1.Recent progress in direct numerical simulations (DNSs) of stratified turbulent flows has led to increasing attention to the validity of the constancy of the dissipation flux coefficient Γ in the Osborn’s eddy diffusivity model. Motivated by lack of observational estimates of Γ, particularly under weakly stratified deep-ocean conditions, this study estimates Γ using deep microstructure profiles collected in various regions of the North Pacific and Southern Oceans. It is shown that Γ is not constant but varies significantly with the Ozmidov/Thorpe scale ratio ROT in a fashion similar to that obtained by previous DNS studies. Efficient mixing events with Γ ~ O(1) and ROT ~ O(0.1) tend to be frequently observed in the deep ocean (i.e., weak stratification), while moderate mixing events with Γ ~ O(0.1) and ROT ~ O(1) tend to be observed in the upper ocean (i.e., strong stratification). The observed negative relationship between Γ and ROT is consistent with a simple scaling that can be derived from classical turbulence theories. In contrast, the observed results exhibit no definite relationships between Γ and the buoyancy Reynolds number Reb, although Reb has long been thought to be another key parameter that controls Γ.This study was supported by MEXT KAKENHI Grant JP15H05824 and JSPS KAKENHI Grant JP15H02131.2019-02-1

Interannual variability and future projection of summertime ocean wave heights in the western North Pacific

International audienceA 70-yr (from 1985?1995 to 2055?2065) change of decadal mean summertime extreme significant wave heights (SWH) in the western North Pacific under CO2-induced global warming condition is projected. For this purpose, possible atmospheric fields under future global warming are derived from 10-yr time-slice experiments using a T106 AGCM. The future changes of SWH are assessed by an empirical approach, where possible changes of SWH are estimated using a linear regression model which shows an empirical relationship between SWH anomalies and an eastward shift of the monsoon trough. It is projected that SWH increases by up to ~0.4 m over a wide area of the western North Pacific

Fundamental studies on techniques of mass-production of fry of the black porgy, Mylio macrocephalus : I. On the spawning induced by injection of a preparation of mammalian gonadotropic hormones

　鹹水養池で粗放的に養殖されたクロダイ雌魚，生殖腺刺激ホルモンとしてシナホリンを注射した. のち，雄魚とともに水槽に収容して，下記のような結果を得た. 1) 産卵期に入る前の未熟期から約1ヶ月聞にわたり， 4回の注射により全量62RUを投与した満4 年魚において良好な産卵結果が得られたほか，満3年魚においても産卵がみられた. 2) 産卵期における未完熟魚に１同(20RU) または2回(40RU) の注射により，満4年魚に産卵 個体が多くみられた.Using the adults of 3 or 4 years of age of black porgy which were cultured extensively in the brackish-water fishponds, some trials were made in the artificial inducement of spawning of the fish. Female fish were mated with males in small concrete tanks after intramuscular injections of saline solution of "Synahorin" (mammalian gonadotropin preparation), and the results obtained were as follows. 1) Development of the ovaries of every semimature female recipient fish was evidently hastened by injections prior to the spawning season or early in that. 2) Then, two out of three females of 4 years of age successfully spawned after 62 RU in total dosage was respectively given by means of injecting in four doses during about one month, while partial spawning occurred in only one out of four females of 3 years with the above and additional injections. 3) In the spawning season, as the results of injections of respective dosage of 20 RU (once) or 40 RU (twice) into many females which were ripening but had not yet spawned, some of them mostly in females of 4 years of age could be induced to spawn

Thermophysical Properties Measurement of High-Temperature Liquids Under Microgravity Conditions in Controlled Atmospheric Conditions

Microgravity conditions have advantages of measurement of surface tension and viscosity of metallic liquids by the oscillating drop method with an electromagnetic levitation (EML) device. Thus, we are preparing the experiments of thermophysical properties measurements using the Materials-Science Laboratories ElectroMagnetic-Levitator (MSL-EML) facilities in the international Space station (ISS). Recently, it has been identified that dependence of surface tension on oxygen partial pressure (Po2) must be considered for industrial application of surface tension values. Effect of Po2 on surface tension would apparently change viscosity from the damping oscillation model. Therefore, surface tension and viscosity must be measured simultaneously in the same atmospheric conditions. Moreover, effect of the electromagnetic force (EMF) on the surface oscillations must be clarified to obtain the ideal surface oscillation because the EMF works as the external force on the oscillating liquid droplets, so extensive EMF makes apparently the viscosity values large. In our group, using the parabolic flight levitation experimental facilities (PFLEX) the effect of Po2 and external EMF on surface oscillation of levitated liquid droplets was systematically investigated for the precise measurements of surface tension and viscosity of high temperature liquids for future ISS experiments. We performed the observation of surface oscillations of levitated liquid alloys using PFLEX on board flight experiments by Gulfstream II (G-II) airplane operated by DAS. These observations were performed under the controlled Po2 and also under the suitable EMF conditions. In these experiments, we obtained the density, the viscosity and the surface tension values of liquid Cu. From these results, we discuss about as same as reported data, and also obtained the difference of surface oscillations with the change of the EMF conditions

Legionella pneumophila infection induces programmed cell death, caspase activation, and release of high-mobility group box 1 protein in A549 alveolar epithelial cells: inhibition by methyl prednisolone

<p>Abstract</p> <p>Background</p> <p><it>Legionella pneumophila </it>pneumonia often exacerbates acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Apoptosis of alveolar epithelial cells is considered to play an important role in the pathogenesis of ALI and ARDS. In this study, we investigated the precise mechanism by which A549 alveolar epithelial cells induced by <it>L. pneumophila </it>undergo apoptosis. We also studied the effect of methyl prednisolone on apoptosis in these cells.</p> <p>Methods</p> <p>Nuclear deoxyribonucleic acid (DNA) fragmentation and caspase activation in <it>L. pneumophila</it>-infected A549 alveolar epithelial cells were assessed using the terminal deoxyribonucleotidyl transferase-mediated triphosphate (dUTP)-biotin nick end labeling method (TUNEL method) and colorimetric caspase activity assays. The virulent <it>L. pneumophila </it>strain AA100jm and the avirulent <it>dotO </it>mutant were used and compared in this study. In addition, we investigated whether methyl prednisolone has any influence on nuclear DNA fragmentation and caspase activation in A549 alveolar epithelial cells infected with <it>L. pneumophila</it>.</p> <p>Results</p> <p>The virulent strain of <it>L. pneumophila </it>grew within A549 alveolar epithelial cells and induced subsequent cell death in a dose-dependent manner. The avirulent strain <it>dotO </it>mutant showed no such effect. The virulent strains of <it>L. pneumophila </it>induced DNA fragmentation (shown by TUNEL staining) and activation of caspases 3, 8, 9, and 1 in A549 cells, while the avirulent strain did not. High-mobility group box 1 (HMGB1) protein was released from A549 cells infected with virulent <it>Legionella</it>. Methyl prednisolone (53.4 μM) did not influence the intracellular growth of <it>L. pneumophila </it>within alveolar epithelial cells, but affected DNA fragmentation and caspase activation of infected A549 cells.</p> <p>Conclusion</p> <p>Infection of A549 alveolar epithelial cells with <it>L. pneumophila </it>caused programmed cell death, activation of various caspases, and release of HMGB1. The dot/icm system, a major virulence factor of <it>L. pneumophila</it>, is involved in the effects we measured in alveolar epithelial cells. Methyl prednisolone may modulate the interaction of <it>Legionella </it>and these cells.</p