Nanostructured Bulk Copper Fabricated by Accumulative Roll Bonding

Takata, Naoki,Lee, Seong-Hee,Lim, Cha-Yong,Kim, Sang-Shik,Tsuji, Nobuhiro American Scientific Publishers 2007 Journal of Nanoscience and Nanotechnology Vol.7 No.11

<P>In this study, we tried to fabricate the nanostructured bulk copper alloys by a severe plastic deformation process. The sheets of copper alloys (OFC, PMC90, and DLP) were heavily deformed to an equivalent strain of 6.4 by the accumulative roll-bonding (ARB) process. The microstructure and the mechanical property of the fabricated specimens were systematically investigated. The microstructure was finely subdivided with increasing the equivalent strain by the ARB process. The severely deformed copper alloys exhibited the ultrafine lamellar boundary structure where the mean lamella spacing was about 200 nm. The strength significantly increased with decreasing the lamella spacing in the ARB processed copper alloys. Especially, the tensile strength of the DLP alloys ARB processed by 8 cycles (the equivalent strain of 6.4) reached to 520 MPa, which was about three times higher than that of same materials with conventional grain size of 10-100 <I>μ</I>m. On the other hand, the total elongation greatly dropped only by 1 ARB cycle corresponding to an equivalent strain of 0.8, which was around 3%. However, the total elongation increased again with increasing the number of the ARB cycle, and it reached to 10% after 8 cycles. The recovery of the total elongation could be recognized in all studied copper alloys. The obtained stress-strain curves showed that the improvement of the total elongation was caused by the increase in the post-uniform elongation. It can be concluded that the nanostructured copper alloys sheets having high strength without a large loss of ductility could be fabricated by the ARB process.</P>

Delayed differentiation of potent effector CD8⁺ T cells reducing viremia and reservoir seeding in acute HIV infection

Takata, Hiroshi,Buranapraditkun, Supranee,Kessing, Cari,Fletcher, James L. K.,Muir, Roshell,Tardif, Virginie,Cartwright, Pearline,Vandergeeten, Claire,Bakeman, Wendy,Nichols, Carmen N.,Pinyakorn, Sute American Association for the Advancement of Scienc 2017 Science Translational Medicine Vol.9 No.377

<P>CD8(+) T cells play a critical role in controlling HIV viremia and could be important in reducing HIV-infected cells in approaches to eradicate HIV. The simian immunodeficiency virus model provided the proof of concept for a CD8(+) T cell-mediated reservoir clearance but showed conflicting evidence on the role of these cells to eliminate HIV-infected cells. In humans, HIV-specific CD8(+) T cell responses have not been associated with a reduction of the HIV-infected cell pool in vivo. We studied HIV-specific CD8(+) T cells in the RV254 cohort of individuals initiating ART in the earliest stages of acute HIV infection (AHI). We showed that the HIV-specific CD8(+) T cells generated as early as AHI stages 1 and 2 before peak viremia are delayed in expanding and acquiring effector functions but are endowed with higher memory potential. In contrast, the fully differentiated HIV-specific CD8(+) T cells at peak viremia in AHI stage 3 were more prone to apoptosis but were associated with a steeper viral load decrease after ART initiation. Their capacity to persist in vivo after ART initiation correlated with a lower HIV DNA reservoir. These findings demonstrate that HIV-specific CD8(+) T cell magnitude and differentiation are delayed in the earliest stages of infection. These results also demonstrate that potent HIV-specific CD8(+) T cells contribute to the reduction of the pool of HIV-producing cells and the HIV reservoir seeding in vivo and provide the rationale to design interventions aiming at inducing these potent responses to cure HIV infection.</P>

Mid-Holocene forcing of the Tsushima Warm Current to the coastal environments in southwestern Japan with a view to foraminiferal faunas

Takata, Hiroyuki,Nishida, Naohisa,Ikehara, Ken,Katsuki, Kota,Khim, Boo-Keun Elsevier 2018 QUATERNARY INTERNATIONAL Vol.482 No.-

<P><B>Abstract</B></P> <P>We investigated fossil benthic and planktonic foraminifera in sediment cores FV10-05 and FV10-06-2, off Fukuoka, southwestern Japan to evaluate the impact of the Tsushima Warm Current on coastal environments around the strait between southeastern Korea and southwestern Japan during the early to middle Holocene. A cluster analysis of benthic foraminifera in these cores established four sample clusters (A, B, C, and D), which are interpreted as indicators of relatively high energy condition due to wave/current processes. Clusters A and C, characterized by attached taxa, became dominant at ∼6.6 ka. Such faunal changes are consistent with the current-influenced sedimentation, confirming that the Tsushima Warm Current reached its present-day distribution at that time. A hiatus at ∼8–7 ka has been reported in cores from deeper water off Fukuoka, whereas our shallow core shows deposition under high energy conditions was continuous even at ∼8–7 ka near the coast off river mouth. Across the strait, the maximum landward extent of benthic foraminifera occurred in the Nakdong River delta (southeastern Korea) in ∼8–7 ka, and an outer bay fauna of benthic foraminifera with seagrass beds occurred transiently in the restricted bay of the San-in district (southwestern Japan) at that time. The evolution of the Tsushima Warm Current during the early to middle Holocene thus appears to play an important role in coastal environments not only in the strait areas between southeastern Korea and southwestern Japan, but also in the San-in district.</P>

Biotic response of benthic foraminifera in Aso-kai lagoon, central Japan, to changes in terrestrial climate and ocean conditions (~AD 700–1600)

Takata, Hiroyuki,Tanaka, Satoshi,Seto, Koji,Sakai, Saburo,Takayasu, Katsumi,Khim, Boo-Keun Springer-Verlag 2014 Journal of paleolimnology Vol.51 No.3

INTEGRATION OF HUMANISTIC THERAPEUTIC APPROACH(ATA) WITH SOCIAL SKILLS TRAINING(SST) SIGNIFICANTLY IMPROVES SATISFACTORY QUALITY OF LIFE(QOL) AND INCREASES EFFECTIVENESS OF REHABILITATION TREATMENT FOR CHRONIC SCHIZOPHRENIC IN-PATIENTS

Takata Yamamoto 용인정신의학연구소 1994 용인정신의학보 Vol.1 No.2

Central Equatorial Pacific benthic foraminifera during the mid-Brunhes dissolution interval: Ballasting of particulate organic matter by biogenic silica and carbonate

Takata, Hiroyuki,Kim, Hyung Jeek,Asahi, Hirofumi,Thomas, Ellen,Yoo, Chan Min,Chi, Sang Bum,Khim, Boo-Keun Elsevier 2019 Quaternary science reviews Vol.210 No.-

<P><B>Abstract</B></P> <P>We evaluated the response of Quaternary abyssal benthic foraminifera in cores PC5101 (2º00.86′N, 131º34.32′W) and PC5103 (6º00.10′N, 131º28.57′W) of the Central Equatorial Pacific Ocean to the environmental changes over the past ∼520 kyrs, focusing on the mid-Brunhes dissolution interval (∼533–191 ka). We used multi-dimensional scaling (MDS) to derive MDS axis 1, reflecting food supply from low (negative scores) to high (positive scores) amounts, and MDS axis 2, reflecting variability in the food supply. From ∼120 ka on, <I>Epistominella exigua</I>, an indicator of variable food supply, was more abundant in core PC5103 (∼6<SUP>o</SUP>N) than in core PC5101 (∼2<SUP>o</SUP>N), but this was reversed from ∼300 to 250 ka.</P> <P>In core PC5101, MDS axis 1 scores are negatively correlated to the biogenic opal mass accumulation rates (MAR) after 249.6 ka, i.e., lower food supply at higher opal-MAR. In contrast, MDS axis 1 scores are positively correlated to the CaCO<SUB>3</SUB>-MAR from 520.8 to 331.2 ka. Both carbonate and opal skeletons might ballast particulate organic matter (POM) to enhance food supply to the benthos, but our data indicate that carbonate is more efficient and that changes in dominant ballasting of POM by different biominerals thus may have significantly affected the biological pump. During the transitional period (∼327.5–257.1 ka), ballasting of POM changed from control by calcareous plankton to control by siliceous plankton, with a transient period during which the latitudinal pattern of the Intertropical Convergence Zone was opposite to its modern pattern, with the more variable food supply at ∼ 6<SUP>o</SUP>N.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Quaternary abyssal benthic foraminifera were compared in terms of multi-dimensional scaling (MDS) in the Central Equatorial Pacific Ocean. </LI> <LI> In core PC5101, located closer to the equator, MDS axis 1 scores are negatively correlated to the biogenic opal mass accumulation rates (MAR) after 249.6 ka. </LI> <LI> In contrast, core PC5101 shows that MDS axis 1 scores are positively correlated to the CaCO<SUB>3</SUB>-MAR from 520.8 to 331.2 ka. </LI> <LI> Ballasting of particulate organic matter changed from control by calcareous plankton to control by siliceous plankton during ∼327.5–257.1 ka. </LI> <LI> During a transient period, the latitudinal pattern of the Intertropical Convergence Zone was opposite to its modern pattern, with the more variable food supply at ∼6°N. </LI> </UL> </P>

HIGH-ENERGY EMISSIONS FROM THE GAMMA-RAY BINARY LS 5039

Takata, J.,Leung, Gene C. K.,Tam, P. H. T.,Kong, A. K. H.,Hui, C. Y.,Cheng, K. S. IOP Publishing 2014 The Astrophysical journal Vol.790 No.1

<P>We study mechanisms of multi-wavelength emissions (X-ray, GeV, and TeV gamma-rays) from the gamma-ray binary LS 5039. This paper is composed of two parts. In the first part, we report on results of observational analysis using 4 yr data of the Fermi Large Area Telescope. Due to the improvement of instrumental response function and increase of the statistics, the observational uncertainties of the spectrum in the similar to 100-300 MeV bands and > 10 GeV bands are significantly improved. The present data analysis suggests that the 0.1-100 GeV emissions from LS 5039 contain three different components: (1) the first component contributes to <1 GeV emissions around superior conjunction, (2) the second component dominates in the 1-10 GeV energy bands, and (3) the third component is compatible with the lower-energy tail of the TeV emissions. In the second part, we develop an emission model to explain the properties of the phase-resolved emissions in multi-wavelength observations. Assuming that LS 5039 includes a pulsar, we argue that emissions from both the magnetospheric outer gap and the inverse-Compton scattering process of cold-relativistic pulsar wind contribute to the observed GeV emissions. We assume that the pulsar is wrapped by two kinds of termination shock: Shock-I due to the interaction between the pulsar wind and the stellar wind and Shock-II due to the effect of the orbital motion. We propose that the X-rays are produced by the synchrotron radiation at the Shock-I region and the TeV gamma-rays are produced by the inverse-Compton scattering process at the Shock-II region.</P>

Holocene benthic foraminiferal faunas in coastal deposits of the Nakdong River delta (Korea) and Izumo Plain (Japan)

Takata, H.,Khim, B.K.,Cheong, D.,Shin, S.,Takayasu, K.,Park, Y.H.,Lim, H.S. Pergamon Press 2016 QUATERNARY INTERNATIONAL Vol.392 No.-

<P>We documented the Holocene benthic foraminifera in the coastal deposits based on drilled cores ND-01 (Nakdong River delta, southeastern Korea) and HS02 (Izumo Plain, southwestern Japan). The rapid deepening and subsequent gradual shoaling during the Holocene were recognized from the stratigraphic distribution of five clusters (A to E) and the ratio of planktonic foraminifera to the sum of benthic and planktonic foraminifera (P/T ratio) in core ND-01. Comparison of benthic foraminiferal faunas indicated that the faunal composition differs somewhat between the Nakdong River delta and Izumo Plain or Urauchi Bay (the East China Sea). The relationships between MDS axis 1 and the rarefaction and between MDS axis 1 and the RAC kurtosis showed positive and negative linear-like trends, respectively, in both the Nakdong River delta and the Izumo Plain. The biotic response of benthic foraminifera to taxonomic loss also seemed to be common in that both coastal deposits experienced shoaling or enclosing of the bay environments. Despite the different occurrence of benthic foraminifera between the Nakdong River delta and Izumo Plain, transient changes of benthic foraminifera in both areas at similar to 8 ka might have been caused by the enhanced influence of the Tsushima Warm Current. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.</P>

A Non-thermal Pulsed X-Ray Emission of AR Scorpii

Takata, J.,Hu, C.-P.,Lin, L. C. C.,Tam, P. H. T.,Pal, P. S.,Hui, C. Y.,Kong, A. K. H.,Cheng, K. S. American Astronomical Society 2018 The Astrophysical journal Vol.853 No.2

<P>We report the analysis result of UV/X-ray emission from AR. Scorpii, which is an intermediate polar (IP) composed of a magnetic white dwarf and an M-type star, with the XMM-Newton data. The X-ray/UV emission clearly shows a large variation over the orbit, and their intensity maximum (or minimum) is located at the superior conjunction (or inferior conjunction) of the M star orbit. The hardness ratio of the X-ray emission shows a small variation over the orbital phase and shows no indication of the absorption by an accretion column. These properties are naturally explained by the emission from the M star surface rather than that from the accretion column on the white dwarf's (WD) star, which is similar to usual IPs. Additionally, the observed X-ray emission also modulates with the WD's spin with a pulse fraction of similar to 14%. The peak position is aligned in the optical/UV/X-ray band. This supports the hypothesis that the electrons in AR. Scorpii are accelerated to a relativistic speed and emit non-thermal photons via the synchrotron radiation. In the X-ray bands, evidence of the power-law spectrum is found in the pulsed component, although the observed emission is dominated by the optically thin thermal plasma emissions with several different temperatures. It is considered that the magnetic dissipation/reconnection process on the M star surface heats up the plasma to a temperature of several keV and also accelerates the electrons to the relativistic speed. The relativistic electrons are trapped in the WD's closed magnetic field lines by the magnetic mirror effect. In this model, the observed pulsed component is explained by the emissions from the first magnetic mirror point.</P>

Correlation between faunal transitions of benthic foraminifera and ballasting of particulate organic carbon by siliceous plankton during the Holocene off San-in district, southwestern Japan

Takata, Hiroyuki,Itaki, Takuya,Ikehara, Ken,Khim, Boo-Keun E. Arnold Distributed in North America by Cambridg 2018 The Holocene Vol.28 No.3