Kanako Sato

The role of meso-scale eddies in mixed layer deepening and mode water formation in the western North Pacific

Distributions of mixed layer depths around the centers of anti-cyclonic and cyclonic eddies in the North Pacific Ocean were composited by using satellite-derived sea surface height anomaly data and Argo profiling float data. The composite distributions showed that in late winter, deeper mixed layers were more (less) frequently observed inside the cores of the anti-cyclonic (cyclonic) eddies than outside. This relationship was the clearest in the region of 140°E–160°W and 35°N–40°N, where the temperature and salinity of the deep mixed layers were similar to those of the lighter variety of central mode water (L-CMW). A simple one-dimensional bulk mixed layer model showed that both strong sea-surface heat and momentum fluxes and weak preexisting stratification contributed to formation of the deep mixed layer. These conditions were associated with the anti-cyclonic eddies, suggesting that these eddies are important in the formation of mode waters, particularly L-CMW.

ζ potential measurement of volcanic rocks from Aso caldera

[1] We deduced the z potential of various rocks in Aso caldera from streaming potential measurements in laboratory. In contrast to the conventional observation that the z potential of crustal rocks is mostly negative under typical geologic conditions, almost half of the samples equilibrated with dilute KCl solution show positive values of z potential at pH 4.5–5.5. The samples showing positive z are characterized by relatively low SiO2 content and abundance of elements having high isoelectric points, and found to be localized around the summit of Mt. Takadake where the positive correlation between self-potential (SP) and altitude is observed. We emphasize that measurements of z potential of volcanic rocks are very important to give more appropriate interpretations of SP data from volcanic fields. INDEX TERMS: 0634 Electromagnetics: Measurement and standards; 0925 Exploration Geophysics: Magnetic and electrical methods; 5199 Physical Properties of Rocks: General or miscellaneous; 8499 Volcanology: General or miscellaneous; 1832 Hydrology: Groundwater transport. Citation: Hase, H., T. Ishido, S. Takakura, T. Hashimoto, K. Sato, and Y. Tanaka, z potential measurement of volcanic rocks from Aso caldera, Geophys. Res. Lett., 30(23), 2210, doi:10.1029/2003GL018694, 2003.

Anticyclonic Eddies in the Alaskan Stream

Abstract Anticyclonic eddies propagating southwestward in the Alaskan Stream (AS) were investigated through analysis of altimetry data from satellite observations during 1992–2006 and hydrographic data from profiling float observations during 2001–06. Fifteen long-lived eddies were identified and categorized based on their area of first appearance. Three eddies were present at the beginning of the satellite observations; another three formed in the eastern Gulf of Alaska off Sitka, Alaska; and four were first detected at the head of the Gulf of Alaska near Yakutat, Alaska. The other five eddies formed along the AS between 157° and 169°W, and were named AS eddies. While the eddies that formed in the Gulf of Alaska mainly decayed before exiting the Gulf of Alaska, the AS eddies mostly crossed the 180° meridian and reached the western subarctic gyre. Four of five AS eddies formed under negative or weakly positive wind stress curls, which possibly caused AS separation from the coast. Comparison of eddy propag...

The accumulation of11C-methionine in cerebral glioma patients studied with PET

SummaryFourteen patients with cerebral gliomas were studied with positron emission tomography (PET) using L-[methyl-11C]methionine (11C-MET). Positive images of tumour were obtained in all cases regardless of histological grades. The analysis of differential absorption ratio (DAR) showed the higher accumulation of11C-MET in high grade gliomas than in low grade gliomas. PET study with11C-MET will be of great value not only in delineating the location of gliomas, but also in making a qualitative diagnosis from the view point of the biological properties of gliomas.

Structure and Modification of the South Pacific Eastern Subtropical Mode Water

Abstract Using all available temperature and salinity profiles obtained by Argo floats from July 2004 to June 2007, this study investigated the structure and modification of the South Pacific Eastern Subtropical Mode Water (SPESTMW). Based on the observed characteristics of the vertical minima of potential vorticity over the subtropical South Pacific, SPESTMW is defined as water with potential vorticity magnitude less than 2.5 × 10−10 m−1 s−1 and thickness exceeding 40 m. It is found between 35°–5°S and 160°–70°W and has a temperature of 13°–26°C, salinity greater than 34.0, and density of 24.5–25.8 kg m−3 at its core. This study confirmed that vertical changes in temperature and salinity tend to compensate for each other in terms of density changes, resulting in favorable salt fingering conditions, as previously reported. By analyzing many profiles of Argo data in spring immediately after the SPESTMW formation period, its temperature and salinity are vertically uniform in the formation region, but large ...

Relationship of maximum tropical cyclone intensity to sea surface temperature and tropical cyclone heat potential in the North Pacific Ocean

[1] We investigated whether the maximum intensity of tropical cyclones (TC) in the North Pacific Ocean depends on sea surface temperature (SST) and tropical cyclone heat potential (TCHP). The study used reanalysis data sets for both the oceans and atmosphere: daily, 10-day, and monthly oceanic data sets; six-hour and monthly atmospheric data sets; and a daily satellite SST data set, for the July-to-October season from 2002 to 2005. For each TC, we summed TCHP from the time of genesis to the time of first reaching a minimum central pressure (MCP), to obtain an accumulated TCHP. In a linear regression analysis, the relationship between maximum TC intensity and accumulated TCHP differed between the eastern and western Pacific: high values of accumulated TCHP were needed before a TC attained a certain MCP in the western Pacific. In addition, the background convective available potential energy (CAPE) value was nearly four times larger in the western Pacific than in the eastern Pacific. The static stability was also 6.5% lower, the inertial stability 29.7% higher, and the size of tropical cyclones 38.2% larger in the western Pacific than in the eastern Pacific. The result indicated a deeper Rossby penetration depth and stronger TC in the western Pacific. Finally, we validated the TCHP values derived from three oceanic reanalysis data sets by using Argo profiling float observations. We found that use of only the daily data can reproduce the cooling effect of a passage of a TC, which caused a decrease in the TCHP values.

Circulating Blood Volume in Patients with Subarachnoid Haemorrhage

Summary To establish the fluid management for patients with subarachnoid haemorrhage (SAH), circulating blood volume (BV) was measured by pulse-spectrophotometry using indocyanine green (ICG) in 34 cases with SAH and 20 cases with neurosurgical disorders as control. BV measured immediately after induction of anaesthesia was lower in cases with SAH than that in controls. (62.8±12.3 vs. 73.3±11.2 ml/kg, p<0.01). In cases with SAH, the BV was significantly decreased in females (p<0.05) but not so significantly in males. In female cases with SAH, reduced BV was increased 3 days after operation (p<0.01). In conclusion BV is decreased in cases with SAH, especially in females. Active fluid therapy may be necessary when temporary vascular occlusion is required during aneurysm surgery. Since hypovolaemia may cause symptomatic vasospasm, BV measurement with pulse-spectrophotometry may provide useful information to insure normovolaemia.

Comment on “Importance of pre-existing oceanic conditions to upper ocean response induced by Super Typhoon Hai-Tang” by Z.-W. Zheng, C.-R. Ho, and N.-J. Kuo

[1] Understanding the impact of pre-existing oceanic conditions on the upper ocean response to tropical cyclones (TCs) is one of the important issues for understanding the short-term occurrence of TC-ocean interaction and its impact on TC intensity. Zheng et al. [2008] showed that preexisting cyclonic flow represented by negative sea-surface height anomalies (SSHA) played a crucial role in enhancing sea-surface cooling (SSC) caused by Typhoon Hai-Tang in 2005. On the other hand, the impact of initial oceanic mixedlayer depth and the vertical sea-temperature gradient in the thermocline on the amplitude of SSC has been considered to be small compared with that of the Ekman pumping and entrainment/vertical turbulent mixing [e.g., Wada, 2002]. Therefore, we hardly accept the discussion of Zheng et al. [2008] that the impact of Ekman pumping on SSC is less significant for local SSC occurred in certain areas than that of pre-existing oceanic condition. [2] Zheng et al. [2008] provide no quantitative evidence that SSC caused by the passage of Hai-Tang is irrelevant to the Ekman pumping or that the amplitude of SSC caused by the Ekman pumping is negligibly smaller than that due to relatively low sea surface height (SSH). In this paper, we revisit the relationship between SSC and SSH using a daily oceanic reanalysis dataset [Wada and Usui, 2007] produced by the North Pacific version of the Japan Meteorological Agency/Meteorological Research Institute Multivariate Ocean Variational Estimation system (MOVE) [Usui et al., 2006] in section 2. In section 3, we revisit the impact of the pre-existing oceanic condition on the ocean response to HaiTang using the Argo profiling float data. Section 4 presents our concluding remarks.

Decrease in Intraoperative Brain Surface Temperature in Patients with Subarachnoid Haemorrhage

Summary Background. Recent experimental and clinical evidence of hypothermic protection against neuronal injury creates new interests regarding human brain temperature. However, very little information is available for the brain temperature under certain pathological conditions. In this study, intra-operative brain temperature in patients with subarachnoid haemorrhage (SAH) is particularly addressed. Methods. Brain surface temperature and oxygen saturation of jugular bulb (SjO2) were monitored during early surgery undergone within 48 hours after the onset in patients with SAH (n=16). Those were also measured in patients with unruptured aneurysms during elective surgery as control (n=15). Findings. The brain surface temperature was significantly lower in SAH than control (35.3±0.8 vs. 36.1±0.5°C, P<0.01). The reduction in brain surface temperature was correlated with the severity of the Hunt and Kosniks aneurysmal grade (r=0.837, P<0.01). SjO2 was significantly lower in SAH than control (51.5±7.3 vs. 68.5±7.6%, P<0.01), and was positively correlated with brain surface temperature (r=0.642, P<0.01). Interpretation. These results suggest that the brain temperature and/or the temperature gradient within the brain may be altered in an early period after SAH. Since brain temperature is determined by cerebral blood flow (CBF), metabolism, temperature of both circulating blood and surrounding environment, the brain surface temperature reduction may be explained by depressed CBF and metabolism in SAH.

Chemically Modified Ribozyme to V Gene Inhibits Anti-DNA Production and the Formation of Immune Deposits Caused by Lupus Lymphocytes

A variety of autoantibodies is responsible for the tissue injury in autoimmune diseases. We have demonstrated that the human anti-DNA Ab O-81, of which Ids are commonly detected in renal glomeruli of active lupus nephritis, uses the V3-7 gene. We tried to develop a new therapy for lupus nephritis by using chemically modified ribozymes to specifically inhibit the expression of the mRNA of Ig V gene. The transfection of hammerhead ribozyme or the addition of chemically modified ribozyme against the flanking region of V3-7 caused a potent and selective inhibition of anti-DNA production in V3-7-using B cell clones, but not in irrelevant V gene-using clones in vitro. Chemically modified ribozyme was long-acting and resistant to RNase, and nonspecific cytotoxicity of the ribozyme was negligible. To know the efficacy of the ribozyme in vivo, we used a model of immune complex nephritis in SCID mice in which 5 × 106 PBLs from patients with active lupus nephritis (lupus PBL) were transferred twice. The injection of lupus PBL in combination with chemically modified ribozyme to increase resistance to RNase significantly reduced anti-DNA Ab levels in blood and decreased levels of urinary protein in the immune deposit models. Immunofluorescence study also revealed a marked decrease in IgG deposits at renal glomeruli in the ribozyme-treated group. These results indicate an efficacy of chemically modified ribozyme therapy for autoantibody-mediated immune diseases.