Publications by authors named "Yoichi Tamura"

The Cosmic Gems arc is among the brightest and highly magnified galaxies observed at redshift z ≈ 10.2 (ref. ).

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A fundamental quest of modern astronomy is to locate the earliest galaxies and study how they influenced the intergalactic medium a few hundred million years after the Big Bang. The abundance of star-forming galaxies is known to decline from redshifts of about 6 to 10, but a key question is the extent of star formation at even earlier times, corresponding to the period when the first galaxies might have emerged. Here we report spectroscopic observations of MACS1149-JD1 , a gravitationally lensed galaxy observed when the Universe was less than four per cent of its present age.

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The physical properties and elemental abundances of the interstellar medium in galaxies during cosmic reionization are important for understanding the role of galaxies in this process. We report the Atacama Large Millimeter/submillimeter Array detection of an oxygen emission line at a wavelength of 88 micrometers from a galaxy at an epoch about 700 million years after the Big Bang. The oxygen abundance of this galaxy is estimated at about one-tenth that of the Sun.

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The behavior of a physician when confirming the death of a patient is thought to greatly affect the bereaved family. The required aspects of a physician's behavior after a patient's death are rarely included in physician education. Therefore, the few physicians who confirm the death of a patient should be conscious of the grief of the family members.

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To investigate the effects of different fillers and their contents on the wear of composite resins, four composites (CS: non-porous spherical silica, AS: porous spherical silica, AZ: porous spherical zirconium silicate, and IS: non-porous irregular-shaped silica) were experimentally prepared using different fillers (CS, AZ, AS and IS). Simulated occlusal wear and toothbrush wear were evaluated for these composites and their worn surfaces were observed. The mechanical properties (flexural strength, elastic modulus and hardness) of these composites were determined to examine the relationships between wear and these mechanical properties.

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Lyman-alpha emitters are thought to be young, low-mass galaxies with ages of approximately 10(8) yr (refs 1, 2). An overdensity of them in one region of the sky (the SSA 22 field) traces out a filamentary structure in the early Universe at a redshift of z approximately 3.1 (equivalent to 15 per cent of the age of the Universe) and is believed to mark a forming protocluster.

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Aim: It has been proposed that gonadotropin-releasing hormone (GnRH) analog administered after testicular damage stimulates the recovery of spermatogenesis. However, GnRH analogs suppress the function of sex accessory organs. In this study, we investigated whether testosterone also stimulates the regeneration of rat spermatogenesis after exposure to busulfan.

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An 81-year-old woman consulted us with low abdominal pain. A computed tomography (CT) image showed left hydronephrosis and a mass without calcification at the lower portion of the left ureter. A retrograde urogram showed an irregular filling defect at the lower portion of the left ureter that suggested an obstruction by a malignant ureter tumor.

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Cnot7 is a co-factor of transcription regulation, expressed in a variety of tissues including the lung, liver, thyroid gland, and testis. Our previous study (Nakamura et al., 2004) showed that deletion of the Cnot7 gene in mice caused almost no abnormal phenotypes except for male infertility, due to oligo-astheno-teratozoospermia.

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Spermatogonial stem cells (SSCs), having yet to possess decisive markers, can only be detected retrospectively by transplantation assay. It was reported recently that mouse gonocytes collected from DBA/2 and ICR neonates propagated in vitro. This cultured germ cell, named the germline stem cell (GS cell), produced functional sperm to make progeny when transplanted into recipient mouse testes.

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We generated transgenic mice expressing osteopontin (OPN) under the control of the alpha(1)-antitrypsin promoter. These mice (OPN-T mice) expressed OPN mRNA in liver and kidney, and released a large amount of plasma OPN, which increased after stimulation with turpentine oil. Before sensitization, the number of CD4+ T cells in lymph nodes was significantly higher in OPN-T than nontransgenic mice, and that in spleen was slightly higher, whereas that of CD8+ T cells was no different between OPN-T and nontransgenic mice.

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