140 research outputs found

    Sequential Formation of Low-Mass Stars in the BRC 14 Region

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    We have carried out a deep near-infrared survey of a bright-rimmed molecular cloud, BRC 14 (IC 1848A). The 10 sigma limiting magnitude of the survey is 17.7 mag at the K-band. Seventy-four sources are classified as young stellar object (YSO) candidates based on the near-infrared color-color diagram. The faintest YSO candidates may have masses of an order of tenths of the solar mass, assuming the age of 1 Myr. We examined three values as indicators of star formation; fraction of the YSO candidates, extinctions of all sources, and near-infrared excesses of the YSO candidates. All indicators increase from outside of the rim to the center of the molecular cloud, which suggests that the formation of the low-mass stars in the BRC 14 region proceeds from outside to the center of the cloud.Comment: 12 pages, 5 figures, 1 table, PASJ accepte

    Eradication of Syngeneic Tumor (Meth A Fibrosarcoma) from Mice by Adop­tive Immunotherapy of Immunized Spleen Cells Induced by Corynebacte-rium Parvwn-Pyridme Extract Residue

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    Eradication of immunologically-syngeneic tumors was achieved by adoptive chemotherapy using effector cells induced by Corynebacterium parvum-Pyridine Extract Residue (CP-PER). A mixture of 2 X 10(6) Meth A cells and 0.1 mg CP-PER was subcutaneously inoculated into the back of donor BALB/c mice, with the result that their spleen cells showed an antitumor effect 10 to 13 days after the inoculation. These cells were used as immune cells. Recipient mice were inoculated with 1 X 10(6) Meth A cells, and 2 days later were administered cyclophosphamide. On the following day, 1 X 10(8) immune cells were adoptively transferred into the recipient mice. As a result, the tumor began to regress 7 to 12 days after the adoptive transfer. An immuno-histochemical study of the donors' spleens and the recipients' regressing tumors revealed that the ratio of L3T4+ T cells to Lyt-2+ T cells in the donors' spleens was increased and that the infiltrating cells in the recipients' tumors were mainly composed of L3T4+ T cells. This confirmed that the transfer of L3T4+ T cells led to the infiltration of L3T4+ T cells into the recipients' tumors, causing their eradication.</p

    Tsukuba 32-m VLBI Station

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    The Tsukuba 32-m VLBI station is operated by the Geospatial Information Authority of Japan. This report summarizes activities of the Tsukuba 32-m VLBI station in 2012. More than 200 sessions were observed with the Tsukuba 32-m and other GSI antennas in accordance with the IVS Master Schedule of 2012. We have started installing the observing facilities that will be fully compliant with VLBI2010 for the first time in Japan

    Reducing nonideal to ideal coupling in random matrix description of chaotic scattering: Application to the time-delay problem

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    We write explicitly a transformation of the scattering phases reducing the problem of quantum chaotic scattering for systems with M statistically equivalent channels at nonideal coupling to that for ideal coupling. Unfolding the phases by their local density leads to universality of their local fluctuations for large M. A relation between the partial time delays and diagonal matrix elements of the Wigner-Smith matrix is revealed for ideal coupling. This helped us in deriving the joint probability distribution of partial time delays and the distribution of the Wigner time delay.Comment: 4 pages, revtex, no figures; published versio

    AC resistivity of d-wave ceramic superconductors

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    We model d-wave ceramic superconductors with a three-dimensional lattice of randomly distributed π\pi Josephson junctions with finite self-inductance. The linear and nonlinear ac resistivity of the d-wave ceramic superconductors is obtained as function of temperature by solving the corresponding Langevin dynamical equations. We find that the linear ac resistivity remains finite at the temperature TpT_p where the third harmonics of resistivity has a peak. The current amplitude dependence of the nonlinear resistivity at the peak position is found to be a power law. These results agree qualitatively with experiments. We also show that the peak of the nonlinear resistivity is related to the onset of the paramagnetic Meissner effect which occurs at the crossover temperature TpT_p, which is above the chiral glass transition temperature TcgT_{cg}.Comment: 7 eps figures, Phys. Rev. B (in press

    Resonance sticking in the scattered disk

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    We investigate the dynamical evolution of trans-Neptunian objects (TNOs) in typical scattered disk orbits (scattered TNOs) by performing simulations using several thousand particles lying initially on Neptune-encountering orbits. We explore the role of resonance sticking in the scattered disk, a phenomenon characterized by multiple temporary resonance captures ('resonances' refers to external mean motion resonances with Neptune, which can be described in the form r:s, where the arguments r and s are integers). First, all scattered TNOs evolve through intermittent temporary resonance capture events and gravitational scattering by Neptune. Each scattered TNO experiences tens to hundreds of resonance captures over a period of 4 Gyr, which represents about 38% of the object's lifetime (mean value). Second, resonance sticking plays an important role at semimajor axes a < 250 AU, where the great majority of such captures occurred. It is noteworthy that the stickiest (i.e., dominant) resonances in the scattered disk are located within this distance range and are those possessing the lowest argument s. This was evinced by r:1, r:2 and r:3 resonances, which played the greatest role during resonance sticking evolution, often leading to captures in several of their neighboring resonances. Finally, the timescales and likelihood of temporary resonance captures are roughly proportional to resonance strength. The dominance of low s resonances is also related to the latter. In sum, resonance sticking has an important impact on the evolution of scattered TNOs, contributing significantly to the longevity of these objects.Comment: 24 pages, 7 figures, 1 table. Accepted for publication in Icarus (authors minor information fixed
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