Seasonal Variations of Water Properties and the Baroclinic Flow Pattern in Toyama Bay under the Influence of the Tsushima Warm Current

The seasonal variations of water properties and the baroclinic flow pattern in the upper layer of Toyama Bay, where the shelf breaks in the passway of the eastward coastal branch of the Tsushima Warm Current, have been examined using temperature and salinity data from 26 local stations collected in the 32 years from 1963 through 1994. The results show that the flow pattern around the bay, as inferred from the distributions of the geopotential anomaly at 300 dbar and saline core water, changes remarkably from summer to autumn. There are two obvious inflows into Toyama Bay in a year. One is the surface inflow of less saline water from east of the Noto Peninsula as the coastal-trapped density-driven flow of the coastal branch during the transition from May to July. In September, this inflow is abruptly weakened by a transient northwestward reversal flow in the intermediate layer around 100 m depth. This reversal flow is accompanied by the temporary shallowness of the pycnoclines inside the bay. At that time, another inflow with more saline water of the year occurs in the intermediate layer. From November until January, this reversal flow disappears and a southeastward passing through-flow gradually intensifies across the bay mouth, accompanied by deepening of the pycnoclines inside the bay. According to our interannual analysis over the 32-year study period, this reversal flow has been a stable seasonal phenomenon, except for only 4 years, in which a local warm region or warm eddy developed just north of the Noto Peninsula.     

Dispersion and accumulation of radionuclides in sediment of Urazoko Bay (I)

Contents of⁹⁰Sr,¹³⁷Cs and⁶⁰Co in surface sediments were investigated in and around Urazoko Bay, Fukui Prefecture, where a nuclear power plant has been operating since 1969 and the waste effluent has been released into the sea. The main source of⁹⁰Sr and¹³⁷Cs was recognized to be radioactive fallout, whereas⁶⁰Co was considered to originate from the nuclear power plant. Using the¹³⁷Cs concentration as an indicator of sorption capacity of the sediment, the behaviour of⁶⁰Co was investigated. No seasonal variation was observed in the distribution pattern of⁶⁰Co/¹³⁷Cs ratio and the retention of the heavy initial discharge in 1969 was considered to dominate the radionuclide level in the sediment. Correlation of⁶⁰Co/¹³⁷Cs ratio in the sediment and the distance from the discharge outlet was expressed by a simple exponential function of the distance. It was suggested that the contamination is spreading out gradually to the outer region of Urazoko Bay.     

Shear wave velocity measurement during a standard penetration test

An experiment was carried out to develop a technique to measure shear wave velocity simultaneously with the standard penetration test popular in soil engineering. In the standard penetration test an impact at the bottom of a borehole is produced by weight dropping and may be expected to generate seismic waves. A three-component geophone was set on the ground surface near the borehole and the waves generated were recorded with a magnetic recorder at successive depths of the penetration test. The predominance of the SV wave obtained with this simple method was assured by measurement of the particle orbit. Signal amplitudes decrease with depth and become less than the noise level at a certain depth. Therefore records from deeper sources must be processed to disclose the shear waves. Since waveforms of SV events generated by blows of the penetration test at a given depth are very similar, the signal to noise ratio would be expected to be improved by a stack of wave trains. A paste-up of the radial component after stacking was compared with that before stacking and a refinement was clearly recognized. A vertical distribution of shear wave velocity was obtained by reading the onset time at each depth. Shear wave velocities thus obtained were compared with N values from the standard penetration test and specific resistivities from electrical logging in the same borehole. The data were mutually consistent. This experiment showed that a convenient, precise shear wave velocity measurement can be conducted during the routine work of a standard penetration test.     

Activation energy for thermal release of Ar from some DSDP submarine rocks

From the experimental data on stepwise thermal release of neutron induced ³⁹Ar (³⁹K (n, p) ³⁹Ar) from rocks and minerals, Arrhenius plots were constructed, which gave activation energies for the thermal release process. The activation energies for DSDP Leg 58 and Leg 60 submarine volcanic rocks range from 12 to 20 kcal/mol, whereas those for granodiorites and the K-feldspar separates have activation energies ranging from 37 to 48 kcal/mol. The smaller activation energies for the submarine volcanic rocks reflect the grain boundary diffusion process, while the thermal diffusion of ³⁹Ar from granodiorites and K-feldspar is essentially controlled by a volume diffusion. The grain boundary diffusion for the submarine volcanic rocks suggests that K resides essentially in the grain boundaries.     

CaPtO3 as a novel post-perovskite oxide

Structural, morphological, magnetic, and thermal properties have been investigated for a novel post-perovskite oxide CaPtO₃ synthesized under high pressure. By comparing obtained structural parameters with those for known post-perovskite compounds, we argue that the chemical bond has a strong covalent character. Precise measurements of the Langevin susceptibility χ ₀ = −9.6 × 10⁻⁵ emu/mol and Debye temperature θ ∼ 470 K provide a good opportunity to confirm the reliability of first-principle calculations on predicting physical properties of the Earth’s D” layer.     

Effects of balanced impact damper in structures subjected to walking and vertical seismic excitations

This study investigates whether a balanced impact damper (BID) with a vertically suspended impact body colliding with shock absorbing rubber can suppress vibrations of a floor slab subjected to walking and vertical seismic excitations. The impact body is suspended by coil springs to sustain its deadweight and centralize it within the gap, and collides with the stopper when its amplitude exceeds the specified gap width. The stopper is covered by a shock‐absorbing rubber made of polyurethane gel. The installed BID was evaluated in a single degree‐of‐freedom model of a floor slab subjected to vertical excitations. Simulations revealed that the installed BID properly controls the vibrations. Next, the effects of the BID installed on a steel plate were investigated in shaking table tests. The BID effectively suppressed vertical vibrations of the plate subjected to sinusoidal waves, seismic motions, and walking excitations. In addition, the shaking table tests were accurately simulated by the developed mathematical model of the damper. Copyright © 2015 John Wiley & Sons, Ltd.     

Detailed oceanic structure in the vicinity of the shoal Kokusho-sone

The detailed oceanic structure was observed near the shoal Kokusho-sone (3000N, 12830E), which is located near the axis of the Kuroshio in the East China Sea. The detailed temperature cross-sections along the meridian 12830E, which passes over the shoal, strongly suggest that upwelling is forced along the north slope of the shoal. The behavior of the coastal waters near the Kuroshio front and of the cold water belt along the north-western side of the Kuroshio are also discussed.     

Sweeping-magnetic-twist mechanism for the acceleration of jets in the solar atmosphere

A magnetodynamic mechanism for the acceleration of jets in the solar atmosphere (surges, Brueckner's EUV jets, and so on) is proposed, and a 2.5-dimensional MHD simulation is performed to show how this mechanism operates in the situation of the chromosphere-corona region of the solar atmosphere. It is seen from the result of simulation that together with the release of the magnetic twist, e.g., into a reconnected open flux tube, the mass in the high density twisted loop is driven out into the open flux tube due both to the pinch effect progressing with the packet of the magnetic twist into the open flux tube, and to the j × B force at the front of the packet of the unwinding twist in the off-axis part of the tube. The former, the progressing pinch, is accompanied by an accelerated hot blob, while the latter, the unwinding front of the magnetic twist, drives a cool cylindrical flow, both with velocities of the order of the local Alfvén velocity. One of the characteristic properties of the jet in our model is that the jet, consisting of hot core and cool sheath, has a helical velocity field in it, explaining the thus-far unexplained observed feature.The sudden release of the magnetic twist into an open flux tube is most likely to be due to the reconnection between a twisted loop and the open flux tube. The mass is driven out in the relaxation process of the magnetic twist from the twisted loop to the open flux tube.     

BIOCHEMICAL GENETIC STUDIES ON CUTYLEFISH SEPIELLA MAINDRONI （CEPHALOPODA： SEPIIDAE）——ACTIVE LOCI SCREENING OF ISOZYME

Screening of 46 putative enzyme-coding loci and 4 different kinds of tissues of Sepiella maindroni de Rochebrone, 1884 for enzymatic activities using starch gel electrophoretic technique proved that the 21 enzymes such as AAT, AK, ALP, AP, CK, DIA, ES, FBP, G3PDH, GPI, GRS,IDH, LDH, MDH, MEP, MPI, NP, PGDH, PGM, SOD and XO* , were active to Sepiella maindroni after being stained. The tissue exhibiting stable and clear bands was also determined. Among tissues tested, mantle muscle tissue was the best for electrophoretic survey of isozymes. Buccal bulb muscle, eye and liver were fairly good for some special enzymes, such as DIA, ES, MPI, NT, etc.