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Now showing items 1 - 16 of 459

  • Sound of a ball spline operated at a certain linear velocity

    Ohta, H.   Iwasaki, S.   Kazama, T.   Hoshino, K.  

    This article deals with the sound of light or medium-preloaded ball splines operating at a certain linear velocity. Experimental results showed that the sound waveforms of the ball splines are pulse-like with ball passage period T(p), and sound peaks f(1)-f(8) and f(1)-f(7) appear in the 20 kHz range sound spectra of the light- and medium-p reloaded ball splines, respectively. A supplemental experiment showed that the main cause of the ball spline sound is the collision between the ball and the spline shaft or spline nut at the entrance of the load zone. The measured frequencies of the sound peaks nearly matched the natural radial-bending frequencies of the spline shaft or nut obtained by finite-element method (FEM). This means that the sound peaks are caused by the natural radial-bending vibrations of the spline shaft and nut. Finally, based on the experimental and FEM results, the sound-generating mechanism of the ball splines has been elucidated.
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  • A universal form of slow dynamics in zero-temperature random-field Ising model

    Ohta, H.   Sasa, S.  

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  • The Birth of Mice from Testicular Spermatozoa Retrieved from Frozen Testicular Sections

    Ohta, H.   Sakaide, Y.   Wakayama, T.  

    Male gamete cryopreservation has been widely used for both human reproduction and animal breeding. We investigated whether testicular spermatozoa retrieved from frozen testicular sections (10 or 25 mu m thick) could support the full-term development of normal progeny. For this purpose, frozen testicular sections were prepared from two genetic backgrounds (BDF1 or B6 GFP transgenic mice), and the functional ability of testicular spermatozoa after preservation for 1 day, 1 mo, and 3 mo was assessed by intracytoplasmic sperm injection (ICSI). Testicular spermatozoa were successfully retrieved from frozen testicular sections for the use of ICSI, regardless of the preservation period. The ICSI technique revealed that oocytes (BDF1 or 136 background) injected with testicular spermatozoa prepared from frozen testicular sections developed into normal progeny, even though the sections had been cryopreserved for 3 mo at -30 degrees C. Approximately 15% and 5% of the embryos preserved for 3 mo developed to full term if the testicular spermatozoa were prepared from the 25- and 10-mu m sections, respectively. These results clearly indicate that male gametes can be viably preserved in frozen testicular sections. The technique described herein will allow the preservation of male gametes in the form of a "book" or "file" by mounting the sections on a paper-thin sheet. Furthermore, this technique may be of value in the clinical treatment of severe male infertility, since testicular spermatozoa can easily be found through examination of testicular cross sections rather than by attempts to identify them in testicular cell suspension.
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  • Incorporating bazedoxifene into the treatment paradigm for postmenopausal osteoporosis in Japan

    Ohta, H.   Solanki, J.  

    The incidence of osteoporosis-related fractures in Asian countries is steadily increasing. Optimizing osteoporosis treatment is especially important in Japan, where the rate of aging is increasing rapidlyelderly population is increasing rapidly and life expectancy is among the longest in the world. There are several therapies currently available in Japan for the treatment of postmenopausal osteoporosis, each with a unique risk/benefit profile. A novel selective estrogen receptor modulator, bazedoxifene (BZA), was recently approved for the treatment of postmenopausal osteoporosis in Japan. Results from a 2-year, phase 2 trial in postmenopausal Japanese women showed that BZA significantly improved lumbar spine and total hip bone mineral density compared with placebo, while maintaining endometrial and breast safety, consistent with results from 2 global, phase 3 trials including a 2-year osteoporosis prevention study and a 3-year osteoporosis treatment study. In the pivotal 3-year treatment study, BZA significantly reduced the incidence of new vertebral fractures compared with placebo; in a post hoc analysis of a subgroup of women at higher risk of fractures, BZA significantly reduced the risk of nonvertebral fractures compared with placebo and raloxifene. A 2-year extension of the 3-year treatment study demonstrated the sustained efficacy of BZA over 5 years of treatment. BZA was generally safe and well tolerated in these studies. In a "super-aging" society such as Japan, long-term treatment for postmenopausal osteoporosis is a considerable need. BZA may be considered as a first choice for younger women anticipating long-term treatment, and also an appropriate option for older women who are unable or unwilling to take bisphosphonates.
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  • Electron spin resonance study of Er-concentration effect in GaAs;Er,O containing charge carriers

    Elmasry, F.   Okubo, S.   Ohta, H.   Fujiwara, Y.  

    Er-concentration effect in GaAs;Er,O containing charge carriers (n-type, high resistance, p-type) has been studied by X-band Electron spin resonance (ESR) at low temperature (4.7 K < T < 18 K). Observed A, B, and C types of ESR signals were identical to those observed previously in GaAs:Er,O without carrier. The local structure around Er-2O centers is not affected by carriers because similar angular dependence of g-values was observed in both cases (with/without carrier). For temperature dependence, linewidth and lineshape analysis suggested the existence of Er dimers with antiferromagnetic exchange interaction of about 7 K. Moreover, drastic decrease of ESR intensity for C signal in p-type sample was observed and it correlates with the decrease of photoluminescence (PL) intensity. Possible model for the Er-2O trap level in GaAs:Er,O is discussed from the ESR and PL experimental results.
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  • Alignment correlation terms in beta-ray angular distributions from spin aligned 20F and 20Na

    Nagatomo, T.   Minamisono, K.   Matsuta, K.   Levy, C.D.P.   Sumikama, T.   Ozawa, A.   Tagishi, Y.   Mihara, M.   Ogura, M.   Matsumiya, R.   Fukuda, M.   Yamaguchi, M.   Behr, J.A.   Jackson, K.P.   Fujiwara, H.   Ohta, H.   Yasuno, T.   Hashizume, Y.   Minamisono, T.  

    The beta-ray angular distribution from the purely aligned nuclei, 20F(I pi = 2 +, T 1/2 = 11.00s) and 20Na(I pi = 2 +, T 1/2 = 447.9 ms), have been measured to test the G symmetry in the weak nuclear currents. The alignment terms alphamnplus of mirror pair in the mass number A = 20 system have been obtained as a function of beta-ray energy with the preliminary analysis.
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  • Molecular dynamics evaluation of self-diffusion in Yukawa systems

    Ohta, H.   Hamaguchi, S.  

    Self-diffusion coefficients of Yukawa systems in the fluid phase are obtained from molecular dynamics simulations in a wide range of the thermodynamical parameters. The Yukawa system is a collection of particles interacting through Yukawa (i.e., screened Coulomb) potentials, which may serve as a model for charged dust particles in a plasma or colloidal particles in electrolytes. The self-diffusion coefficients are found to follow a simple scaling law with respect to the system temperature, which is consistent with the universal scaling (i.e., temperature scaling independent of the ratio of interparticle distance to screening length) observed by Robbins et al. [J. Chem. Phys. 88, 3286 (1988)] if the fluid system is near solidification. Also discussed is the velocity autocorrelation function, which is in part used to determine the self-diffusion coefficients through the Green-Kubo formula
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  • Whole-head SQUID system in a superconducting magnetic shield

    Ohta, H.   et. al.  

    A whole-head 64-channel SQUID magnetometer of SNS (Superconductor/ Normal metal / Superconductor) junctions has been constructed to be operated in a superconducting magnetic shield of Bi(Pb)SrCaCuOx demonstrating the sensitivity of 5 femto Tesla in our laboratory only 10 meter far from both an elevator and power transformer banks. Signal-to-noise ratio of data in neuromagnetic measurements is exellent because a SQUID of SNS junctions has a smaller telegraph noie than that of SIS tunnel junctions and because shielding factors of the superconducting magnetic shield does not reduce even at as low frequencies as 0.05 Hz unlike that of Permalloy shield room. A movie is made to compare the evoked current dipole in the MEG data with the MRI images.
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  • A Confiscation Case Involving a Novel Barbiturate Designer Drug

    Ohta, H.   Suzuki, Y.   Sugita, R.   Suzuki, S.   Ogasawara, K.  

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  • Variation after parity projection calculation with the Skyrme interaction for light nuclei

    Ohta, H.   Yabana, K.   Nakatsukasa, T.  

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  • Classical interatomic potentials for Si–O–F and Si–O–Cl systems

    Ohta, H.   Hamaguchi, S.  

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  • The Observation of an Ultradian Rhythm of Heart Rate in Low Birth Weight Infants

    Ohta, H.   Cho, K.   Matsumoto, Y.   Matsuda, T.   Ohyu, J.   Fujimoto, S.   Honma, K.  

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  • Cryopreservation of the sperm of the Japanese bitterling

    Ohta, H.   Kawamura, K.   Unuma, T.   Takegoshi, Y.  

    Sperm of the Japanese bitterling Tanakia limbata that had been cryopreserved with 5 or 10%methanol plus 95 or 90%foetal bovine serum (FBS) showed higher percentage and longer duration of motility than those that had been cryopreserved with 90%FBS and 10%DMSO, glycerol, N,N-dimethylacetamide or N,N-dimethylformamide. Foetal bovine serum, used as extender, had some cryoprotective effects when spermatozoa were cooled either with 10%methanol or without methanol. Spermatozoa, cooled to −40°C and then immersed in liquid nitrogen, had greater post-thaw motility than those cooled to −20, −60, or −80°C. The post-thaw percentage of motile spermatozoa increased significantly (P< 0·001) with decreases in the freezing rate from 60 to 5°C min−1. These results indicate that 10%methanol plus 90%foetal bovine serum is a suitable diluent for cryopreservation of bitterling spermatozoa and that samples should be cooled to −40°C at a low freezing rate for effective storage.
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  • Examination of 5-Alkoxyninhydrins as Latent Fingerprint Visualization Reagents

    Ohta, H.   Ogasawara, K.   Suzuki, Y.   Sugita, R.   Suzuki, S.  

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  • Codoping effect of O2 into Er-doped InP epitaxial layers grown by OMVPE

    Ohta, H.   Urakawa, C.   Nakashima, Y.   Yoshikawa, J.   Koide, T.   Kawamoto, T.   Fujiwara, Y.   Takeda, Y.  

    The temperature dependence of ESR in InP:Er and the O2 codoping effect in InP:Er have been studied by X-band ESR measurement at low temperature. The ESR at around g=6, which corresponds to Er3+ site with Td symmetry, lost it's intensity quickly as the temperature is increased and disappeared above 12K. The temperature dependence of the integrated intensity turned out to be different from simple Curie law. The intensity of the ESR at around g=6 decreased as O2 is codoped into InP:Er. No new ESR was observed in O2 codoped InP:Er in contrast to the results of O2 codoped GaAs:Er. These results are discussed in connection with the O2 codoping effect of photoluminescence spectra.
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  • Spectroscopic study of Kondo insulator YbB12 using a free electron laser

    Ohta, H.   Nanba, T.   Lehnert, K.   Allen, S.J.   Motokawa, M.   Iga, F.   Kasaya, M.  

    The bolometric response of Kondo insulator YbB12 has been studied for the first time in the energy region from 4 to 130 cm−1 at 1.5 K using the free-electron laser (FEL) at University of California at Santa Barbara. The increases of response are observed at around 50 and 130 cm−1 and they are discussed in connection with the gap structure proposed by Sugiyama et al. previously.
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