Showing papers by "Waseda University published in 2000"
TL;DR: In this paper, the authors consider the brane world with a negative tension and derive the effective gravitational equations, which reduce to the conventional Einstein equations in the low energy limit, in which all the matter forces except gravity are confined on the 3-brane in a 5-dimensional spacetime with ${Z}_{2}$ symmetry.
Abstract: We carefully investigate the gravitational equations of the brane world, in which all the matter forces except gravity are confined on the 3-brane in a 5-dimensional spacetime with ${Z}_{2}$ symmetry. We derive the effective gravitational equations on the brane, which reduce to the conventional Einstein equations in the low energy limit. From our general argument we conclude that the first Randall-Sundrum-type theory predicts that the brane with a negative tension is an antigravity world and hence should be excluded from the physical point of view. Their second-type theory where the brane has a positive tension provides the correct signature of gravity. In this latter case, if the bulk spacetime is exactly anti--de Sitter spacetime, generically the matter on the brane is required to be spatially homogeneous because of the Bianchi identities. By allowing deviations from anti--de Sitter spacetime in the bulk, the situation will be relaxed and the Bianchi identities give just the relation between the Weyl tensor and the energy momentum tensor. In the present brane world scenario, the effective Einstein equations cease to be valid during an era when the cosmological constant on the brane is not well defined, such as in the case of the matter dominated by the potential energy of the scalar field.
1,350 citations
TL;DR: It is shown, in a bird, that the hypothalamus also contains a novel peptide which inhibits gonadotropin release, the first hypothalamic peptide inhibiting gonadotropic hormone reported in a vertebrate.
760 citations
TL;DR: In this article, the authors argue that the success of international strategic alliances requires attention not only to the hard side of alliance management (e.g., financial issues and other operational issues) but also to the soft side, which refers to the development and management of relationship capital in the alliance.
533 citations
TL;DR: Hairpin formation by single-stranded DNA molecules was exploited in a DNA-based computation in order to explore the feasibility of autonomous molecular computing and the satisfiability of a given Boolean formula was examined autonomously.
Abstract: Hairpin formation by single-stranded DNA molecules was exploited in a DNA-based computation in order to explore the feasibility of autonomous molecular computing. An instance of the satisfiability problem, a famous hard combinatorial problem, was solved by using molecular biology techniques. The satisfiability of a given Boolean formula was examined autonomously, on the basis of hairpin formation by the molecules that represent the formula. This computation algorithm can test several clauses in the given formula simultaneously, which could reduce the number of laboratory steps required for computation.
356 citations
TL;DR: Zinc was doped into beta-tricalcium phosphate to develop zinc-releasing biomaterials to promote bone formation and Proliferation of osteoblastic MC3T3-E1 cells was significantly increased on the composite ceramic with a zinc content from 0.6 to 1.20 wt %.
Abstract: Zinc is an essential trace element with stimulatory effects on bone formation. Therefore, zinc was doped into beta-tricalcium phosphate to develop zinc-releasing biomaterials to promote bone formation. The zinc-doped beta-tricalcium phosphate, beta-tricalcium phosphate, and hydroxyapatite powders were mixed at a (Ca+Zn)/P molar ratio of 1.60, followed by sintering into a dense body at 1100 degrees C for 1 h. The sintered body was a composite ceramic consisting of zinc-doped beta-tricalcium phosphate and hydroxyapatite phases. The composite ceramic contained zinc oxide when the zinc content was higher than 1.20 wt %. The composite ceramic released zinc under pseudophysiological conditions. However, the release of calcium and phosphate decreased with an increase in zinc content in a range higher than 0.12 wt % owing to a decrease in solubility of the zinc-doped beta-tricalcium phosphate phase. Proliferation of osteoblastic MC3T3-E1 cells was significantly increased on the composite ceramic with a zinc content from 0.6 to 1.20 wt %, compared with those without zinc. When the zinc content was higher than 1.20 wt %, release of zinc from the zinc oxide caused cytotoxicity. Therefore, the zinc content of the composite ceramic must be <1.20 wt %.
288 citations
TL;DR: In this article, a composite membrane consisting of thin palladium layer deposited on the outer surface of porous ceramics by electroless-plating was proposed to overcome the limitations caused by Pd membranes, such as hydrogen embrittlement.
285 citations
TL;DR: Optical second harmonic spectroscopy is introduced as a powerful supplement for the determination of complex magnetic structures and some earlier conclusions on their magnetic symmetry and properties should be revised.
Abstract: Optical second harmonic spectroscopy is introduced as a powerful supplement for the determination of complex magnetic structures. Experimental efforts are simplified and new degrees of freedom are opened. Thereby, some principal or technical restrictions of neutron or magnetic x-ray diffraction experiments are overcome. High spatial resolution leads to additional information about magnetically ordered matter. As an example, the noncollinear magnetic structure of the hexagonal manganites $R{\mathrm{MnO}}_{3}$ ( $R\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\mathrm{Sc}$, Y, Ho, Er, Tm, Yb, Lu) is analyzed. The results show that some earlier conclusions on their magnetic symmetry and properties should be revised.
276 citations
TL;DR: Although hydroxyapatite and tricalcium phosphate are currently used as bone graft substitutes or coatings on metallic prostheses because of their excellent biocompatibility and osteoconductivity, they do not stimulate bone formation or inhibit bone resorption, and zinc, an essential trace element in many animals, has a direct specific proliferative effect on osteoblastic cells.
Abstract: Although hydroxyapatite (HAP) and tricalcium phosphate (TCP) are currently used as bone graft substitutes or coatings on metallic prostheses because of their excellent biocompatibility and osteoconductivity, they do not stimulate bone formation or inhibit bone resorption. Zinc, an essential trace element in many animals, has a direct specific proliferative effect on osteoblastic cells and has a potent and selective inhibitory effect on osteoclastic bone resorption in vitro. Therefore, zinc-containing beta-tricalcium phosphate (ZnTCP) ceramics and composite ceramics of ZnTCP and HAP (ZnTCP/HAP) were implanted in the femora of New Zealand White rabbits for 4 weeks to promote bone formation. The implants were sintered ceramics with zinc contents of 0 (control), 0.063, 0.316 and 0.633 wt %. Histological and histomorphometrical investigation of the undecalcified sections revealed an increase by 51% (p =.0509) in the area of newly formed bone around the ZnTCP/HAP implants of 0. 316 Zn wt % compared with the control. Plasma zinc concentration was unchanged. An increased bone resorption on the endosteal surface was observed when ZnTCP and ZnTCP/HAP of 0.633 Zn wt % were implanted. To promote bone formation, the optimum zinc content of the calcium phosphate ceramics was therefore 0.316 wt %.
219 citations
TL;DR: In this paper, the curvature invariance of the Randall-Sundrum (RS) single brane-world solution was analyzed in the direction of the Cauchy horizon.
Abstract: We carefully investigate the gravitational perturbation of the Randall-Sundrum (RS) single brane-world solution [L. Randall and R. Sundrum, Phys. Rev. Lett. $83,$ 4690 (1999)], based on a covariant curvature tensor formalism recently developed by us. Using this curvature formalism, it is known that the ``electric'' part of the five-dimensional Weyl tensor, denoted by ${E}_{\ensuremath{\mu}\ensuremath{
u}},$ gives the leading order correction to the conventional Einstein equations on the brane. We consider the general solution of the perturbation equations for the five-dimensional Weyl tensor caused by the matter fluctuations on the brane. By analyzing its asymptotic behavior in the direction of the fifth dimension, we find the curvature invariant diverges as we approach the Cauchy horizon. However, in the limit of asymptotic future in the vicinity of the Cauchy horizon, the curvature invariant falls off fast enough to render the divergence harmless to the brane world. We also obtain the asymptotic behavior of ${E}_{\ensuremath{\mu}\ensuremath{
u}}$ on the brane at spatial infinity, assuming that the matter perturbation is localized. We find it falls off sufficiently fast and will not affect the conserved quantities at spatial infinity. This indicates strongly that the usual conservation law, such as the ADM energy conservation, holds on the brane as far as asymptotically flat spacetimes are concerned.
218 citations
TL;DR: A modular system for the real-time analysis of body movement and gesture, with a particular focus on the understanding of affect and expressive content in gesture, is developed.
Abstract: The goal of the EyesWeb project is to develop a modular system for the real-time analysis of body movement and gesture. Such information can be used to control and generate sound, music, and visual media, and to control actuators (e.g., robots). Another goal of the project is to explore and develop models of interaction by extending music language toward gesture and visual languages, with a particular focus on the understanding of affect and expressive content in gesture. For example, we attempt to distinguish the expressive content from two instances of the same movement
212 citations
TL;DR: In this article, the explicit coordinate transformation which links two exact cosmological solutions of the brane world which have been recently discovered was found, which means that both solutions are exactly the same as each other.
Abstract: We find the explicit coordinate transformation which links two exact cosmological solutions of the brane world which have been recently discovered. This means that both solutions are exactly the same as each other. One of the two solutions is described by the motion of a domain wall in the well-known five-dimensional Schwarzshild-AdS spacetime. Hence, we can easily understand the region covered by the coordinate used by another solution.
TL;DR: Constriction of resistance arteries was found to be correlated with the level of hypertension, and the responses were proportional to the molecular dimensions of the O(2) carriers.
Abstract: The effect of molecular dimension of hemoglobin (Hb)-based O2carriers on the diameter of resistance arteries (A 0, 158 ± 21 μm) and arterial blood pressure were studied in the conscious hamster dor...
TL;DR: The present findings demonstrate that the acute and circadian time-dependent reduction of Per1 and/orPer2 mRNA in the hamster SCN by 8-OH DPAT is strongly correlated with the phase resetting in response to 8- OH DPAT.
Abstract: In mammals, the environmental light/dark cycle strongly synchronizes the circadian clock within the suprachiasmatic nuclei (SCN) to 24 hr. It is well known that not only photic but also nonphotic stimuli can entrain the SCN clock. Actually, many studies have shown that a daytime injection of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH DPAT), a serotonin 1A/7 receptor agonist, as a nonphotic stimulus induces phase advances in hamster behavioral circadian rhythms in vivo, as well as the neuron activity rhythm of the SCN in vitro. Recent reports suggest that mammalian homologs of the Drosophila clock gene, Period (Per), are involved in photic entrainment. Therefore, we examined whether phase advances elicited by 8-OH DPAT were associated with a change of Period mRNA levels in the SCN. In this experiment, we cloned partial cDNAs encoding hamster Per1, Per2, and Per3 and observed both circadian oscillation and the light responsiveness of Period. Furthermore, we found that the inhibitory effect of 8-OH DPAT on hamster Per1 and Per2 mRNA levels in the SCN occurred only during the hamster's mid-subjective day, but not during the early subjective day or subjective night. The present findings demonstrate that the acute and circadian time-dependent reduction of Per1 and/or Per2 mRNA in the hamster SCN by 8-OH DPAT is strongly correlated with the phase resetting in response to 8-OH DPAT.
TL;DR: It is concluded that GAD65-mediated GABA synthesis may be crucially involved in control of emotional behaviour and indispensable for a tonic inhibition that prevents the development of hyperexcitability in the maturating central nervous system.
TL;DR: In this article, the thermal conductivity of polycrystalline samples was found to be unusually low, 20 mW/cmK at 280 K, and it does not change appreciably with the substitution of Ca for Na.
Abstract: The thermal conductivity of polycrystalline samples of $(\mathrm{N}\mathrm{a},\mathrm{C}\mathrm{a}){\mathrm{Co}}_{2}{\mathrm{O}}_{4}$ is found to be unusually low, 20 mW/cmK at 280 K. On the assumption of the Wiedemann-Franz law, the lattice thermal conductivity is estimated to be 18 mW/cm K at 280 K, and it does not change appreciably with the substitution of Ca for Na. A quantitative analysis has revealed that the phonon mean free path is comparable with the lattice parameters, where the point-defect scattering plays an important role. Electronically the same samples show a metallic conduction down to 4.2 K, which strongly suggests that ${\mathrm{NaCo}}_{2}{\mathrm{O}}_{4}$ exhibits a glasslike poor thermal conduction together with a metal-like good electrical conduction. The present study further suggests that a strongly correlated system with layered structure can act as a material of a phonon glass and an electron crystal.
TL;DR: A review of the recent progress in research and development of soft magnetic films for magnetic recording heads of the future is presented in this article primarily on the basis of the work performed by the author's research group.
TL;DR: In this paper, the authors examined the factors in the host countries that would attract FDI by Japanese SMEs and found that SMEs regard the availability of low-wage labor, well-developed infrastructure, and industrial agglomeration as important elements much more than large firms.
Abstract: Japanese manufacturing small and medium enterprises (SMEs) have actively undertaken Foreign Direct Investment (FDI) in Asia since the mid-1980s. FDI contributes to economic growth of the FDI recipient countries, as it brings in not only financial resources for investment but also technologies and managerial know-how, which are important factors for promoting economic growth. Recognizing these benefits of receiving FDI, policy makers in developing countries have formulated various strategies to attract FDI. This paper examines the factors in the host countries that would attract FDI by Japanese SMEs. Our results show the importance of both supply-side and demand-side factors in the recipient countries for attracting FDI by Japanese SMEs. Supply-side factors include abundance of low-wage labor, availability of well-developed infrastructure, and good governance of the host government, while an important demand-side factor is the presence of sizable local market. In addition, Japanese SMEs regard industrial agglomeration, which has a element of both supply and demand factors, as an important factors making FDI decision. Supply-side factors are found to be important for attracting Japanese FDI in developing countries, while demand-factors play a role in attracting Japanese FDI in developed countries. A comparison of the results for SMEs to those for large firms reveals that SMEs are more sensitive to the conditions in the host countries in making their FDI decision. In particular, SMEs regard the availability of low-wage labor, well-developed infrastructure, and industrial agglomeration as important elements much more than large firms. High sensitivity of SMEs to local economic conditions in their decision on FDI location may be explained by their limited availability of financial and human resources and high dependence on overseas production in their business. In light of these findings, we conclude that countries interested in hosting FDI have to provide a very attractive business environment.
TL;DR: In this article, the process of oxidation of the Bi2Te3 surface was investigated by x-ray photoelectron spectroscopy (XPS), and the oxidized surface layer was found to have a definite thickness, with configurations where O is bonded with Bi and Te, and Bi and TE are bonded with three and four oxygens, respectively.
Abstract: The process of oxidation of the Bi2Te3 surface was investigated by x-ray photoelectron spectroscopy (XPS). The oxidized surface layer was found to have a definite thickness, with configurations where O is bonded with Bi and Te, and Bi and Te are bonded with three and four oxygens, respectively. The oxidation time dependence of the oxidized layer thickness d(t) estimated from the XPS behaved as (t-t0)1/2 when d(t) was smaller than the thickness of a single oxidized quintuple atomic layer in our oxide model and behaved as t-t1 when it was larger than that. Experimental data were compared to our oxidation process model for the layered structure with the van der Waals gap and very good agreement was found.
TL;DR: It is concluded that in antral smooth muscle, the expression of InsP3 type 1 receptors may be causally related to the generation of slow waves but not to thegeneration of action potentials.
Abstract: Membrane potential recordings, made from the circular smooth muscle layer of the gastric antrum taken from mutant mice which lacked the inositol trisphosphate (InsP3) type 1 receptor, were compared with those obtained from the stomach of control (wild-type) mice. Immunostaining of gastric muscles indicated that the distribution and form of c-kit positive cells were similar in wild-type and mutant mice. Smooth muscles from wild-type mice generated slow waves that in turn initiated spike potentials, while those from mutant mice were either quiescent or generated irregular bursts of spike potentials. In the presence of nifedipine, slow waves with reduced amplitude were generated in wild-type mice, while all electrical activity was abolished in mutant mice. Acetylcholine depolarized and sodium nitroprusside hyperpolarized the membrane in muscles from both types of mice, being more effective in wild-type mice. Noradrenaline produced similar hyperpolarizations in both types of mice. Transmural nerve stimulation evoked inhibitory junction potentials (IJPs) in both wild-type and mutant mice. In wild-type mice, the IJPs were reduced in amplitude by nitroarginine and converted to a cholinergic excitatory junction potential (EJP) by apamin. In mutant mice, the IJPs were unaffected by nitroarginine or atropine but were abolished by apamin. It is concluded that in antral smooth muscle, the expression of InsP3 type 1 receptors may be causally related to the generation of slow waves but not to the generation of action potentials. A lack of InsP3 receptors attenuates cholinergic excitatory and nitrergic inhibitory responses but does not alter the response to noradrenaline.
TL;DR: In this article, the effects of EGR and intake heating with an exhaust to intake heat exchanger on engine performance and exhaust gas emissions were investigated, especially at low loads, and 3-CFD simulations were conducted to analyze the combustion process in the combustion chamber, using the KIVA-3 code.
Abstract: This paper deals with a diesel engine dual-fueled with natural gas. This system can achieve a high thermal efficiency at higher loads by utilizing the premixed lean natural gas mixture ignited by pilot-injected diesel fuel. At low loads, however, high THC emission and low thermal efficiency were observed. To resolve these problems, effects of EGR and intake heating with an exhaust to intake heat exchanger on engine performance and exhaust gas emissions were investigated, especially at low loads. In addition, 3-CFD simulations were conducted to analyze the combustion process in the combustion chamber, using the KIVA-3 code. The result indicates that thermal efficiency and THC emission at lower loads can be improved by intake air heating combined with EGR.
TL;DR: Transgenic mice carrying the 5' upstream region of the mPer1 gene fused to the luciferase gene demonstrated that a DNA fragment carrying both promoter regions is sufficient to elicit striking circadian oscillation in the SCN and responsiveness to light.
TL;DR: It is shown here that the Fru protein is not detected in the female central nervous system (CNS), despite the similar level of expression of fru mRNA in both male and female CNS.
Abstract: The Drosophila fruitless (fru) gene product Fru has been postulated to be a neural sex-determination factor that directs the development of at least two male-specific characteristics, namely courtship behaviour and formation of the muscle of Lawrence (MOL). The fru gene encodes a putative transcription factor with a BTB domain and two zinc-finger motifs, and with consensus Tra-binding sequences. The binding of Tra to these sequences results in sex-specific alternative splicing of the fru mRNA, leading to production of the 'male-type' or 'female-type' Fru protein. We show here that the Fru protein is not detected in the female central nervous system (CNS), despite the similar level of expression of fru mRNA in both male and female CNS. As ectopic expression of both the 'male-type' (with the sequence for the amino-terminal extension) and 'female-type' (without the sequence for the amino-terminal extension) fru cDNA can induce formation of the MOL in females, the presence or absence of the Fru protein, and not its sex-specific structure, seems to be responsible for the sexually dimorphic actions of the fru gene.
TL;DR: In this article, the authors analyzed clinopyroxene inclusions in zircon of the eclogite and a diamond-bearing biotite gneiss, and concluded that the Ca-Eskola component in the peak metamorphic clincopyroxenes broke down by a retrograde reaction.
Abstract: Abundant exsolved quartz rods occur in matrix clinopyroxene of eclogite from the Kokchetav massif, Kazakhstan. These rocks are diamond-grade, ultrahigh-pressure (UHP) metamorphic rocks that recrystallized at P > 6 GPa and T > 1000 °C. Zircon is an excellent container, which effectively protects peak UHP metamorphic phases from retrogression. Therefore, to ascertain the pre-exsolution composition of the clinopyroxene, we analyzed clinopyroxene inclusions in zircon of the eclogite and a diamond-bearing biotite gneiss. Clinopyroxene in zircon has an excess of Fe 3+ + VI Al over IV Al + Na + K, and calculated cation totals significantly less than 4.0 per six O atoms. The stoichiometry of these pyroxenes can be reconciled if the Ca-Eskola end-member (Ca 0.5 □ 0.5 AlSi 2 O 6 ) is considered. The zircon-hosted clinopyroxene in the eclogite contains up to 9.6 mol% of the Ca-Eskola component, and in the biotite gneiss up to 18.2 mol%, whereas the matrix clinopyroxene contains much less (1.3 mol%, on average). Recalculation of the composition of the matrix clinopyroxene prior to exsolution of quartz rods yields 6.8 mol% Ca-Eskola component, which is consistent with the composition of the clinopyroxene inclusions in zircon. We conclude that the Ca-Eskola component in the peak metamorphic clinopyroxenes broke down by a retrograde reaction: \[2\ Ca_{0.5}{\square}_{0.5}AlSi_{2}O_{6}\ {\rightarrow}\ CaAl_{2}SiO_{6}\ +\ 3\ SiO_{2}\] resulting in exsolution of the quartz rods in the matrix clinopyroxene. Subducted crustal and supracrustal rocks form the Ca-Eskola clinopyroxene at high pressures and temperatures. The vacancy-containing clinopyroxene may have an important bearing on the physico-chemical properties of the subducted slab at upper mantle depth.
TL;DR: In this paper, the authors investigated the Lp-Lq estimate of solutions to the Cauchy problem of linear viscoelastic equation, especially, the diffusion wave property of the Navier-Stokes equation in the compressible fluid case.
Abstract: We investigate the Lp–Lq estimate of solutions to the Cauchy problem of linear viscoelastic equation, especially, the diffusion wave property of linear viscoelastic equation like the Navier–Stokes equation in the compressible fluid case, which was studied by D. Hoff and K. Zumbrum and Tai-P. Liu and W. Wang. Copyright © 2000 John Wiley & Sons, Ltd.
TL;DR: Tyramine has a functional role in the Drosophila olfactory system as a neurotransmitter or a neuromodulator, and hono is the first tyramine receptor mutant, and this study provides the first step toward understanding of the molecular genetics of tyramsine-mediated neural functions in Drosophile.
TL;DR: The intrinsic (gas-phase) stabilities of duplex, self-complementary oligonucleotides were measured in a relative way by subjecting the duplex precursor ions to increasing amounts of collision energy during the collisional-activated decomposition (CAD) events in an ion-trap mass spectrometer.
TL;DR: The combination of PEG-DSPE and the C18 membrane was the most thermodynamically stabilized pair and the dispersion stability of the surface-modified vesicle prepared by this spontaneous incorporation was analyzed by using the critical molecular weight of the polymer for the aggregation of vesicles.
TL;DR: The effect of magnesium and zinc on the growth kinetics of a hydroxyapatite (0001) face in pseudophysiological solutions was investigated in this article, where the growth rates of the face were measured under various concentrations of magnesium or zinc using Moire phase shift interferometry coupled with surface observation by atomic force microscopy.
Abstract: The effect of magnesium and zinc on the growth kinetics of a hydroxyapatite (0001) face in pseudophysiological solutions was investigated. The growth rates of the (0001) face were measured under various concentrations of magnesium or zinc using Moire phase shift interferometry coupled with surface observation by atomic force microscopy. The (0001) face grew not in a spiral growth mode but in a multiple two-dimensional nucleation growth mode. It was shown that the lateral growth of two-dimensional islands on the (0001) face was inhibited by the addition of magnesium or zinc, following an inhibition of the normal growth rate of the face. Although both cations inhibited growth, zinc was found to reduce the growth rate about 1000 times more effectively than magnesium.
TL;DR: In this article, the authors measured the polarization of J/psi and psi(2S) mesons produced in pp collisions at 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992-1995.
Abstract: We have measured the polarization of J/psi and psi(2S) mesons produced in pp collisions at sqrt[s] = 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992-1995. The polarization of promptly produced J/psi [psi(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4 [5.5]
TL;DR: In this article, a set of single crystals of the layered cobaltite Bi2.3-xPbxSr2.6Co2Oy (0 ≤x≤0.44) were prepared by a flux technique.
Abstract: A set of single crystals of the layered cobaltite Bi2.3-xPbxSr2.6Co2Oy (0 ≤x≤0.44) were prepared by a flux technique. The resistivity ρ and the thermopower S along the in-plane direction were measured, and the thermoelectric properties were compared with those of other oxides. The Pb substitution causes a decrease in ρ and an increase in S below 100 K, which improves the power factor S2/ρ by 3–4 times. The transport parameters exhibit an anomaly near 25–50 K, such as a plateau in S and an upturn in ρ, which we ascribe to the reduction of the density of states owing to a pseudogap.