9,992 research outputs found

    The Dense Plasma Torus Around the Nucleus of an Active Galaxy NGC 1052

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    A subparsec-scale dense plasma torus around an active galactic nucleus (AGN) is unveiled. We report on very-long-baseline interferometry (VLBI) observations at 2.3, 8.4, and 15.4 GHz towards the active galaxy NGC 1052. The convex spectra of the double-sided jets and the nucleus imply that synchrotron emission is obscured through free--free absorption (FFA) by the foreground cold dense plasma. A trichromatic image was produced to illustrate the distribution of the FFA opacity. We found a central condensation of the plasma which covers about 0.1 pc and 0.7 pc of the approaching and receding jets, respectively. A simple explanation for the asymmetric distribution is the existence of a thick plasma torus perpendicular to the jets. We also found an ambient FFA absorber, whose density profile can be ascribed to a spherical distribution of the isothermal King model. The coexistence of torus-like and spherical distributions of the plasma suggests a transition from radial accretion to rotational accretion around the nucleus.Comment: 10 pages, to appear in Publ. Astron. Soc. Japan, vol.53, No.2 (2001

    Development of wide area detector for the 2012 model of the 6Li time analyzer neutron detector system

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    A 2012 model 6Li time analyzer neutron detector (LiTA12) system has been developed as a high-count-rate neutron detector. An exclusive function with a center-of-gravity calculation, which not only prevents over-counting due to cross-talk, but also obtains a fine position resolution, has been included. As a highcount-rate detector, this device can detect neutrons with a 3mm position resolution in a detection area of 5×5 cm2 and is arranged as a 16×16 matrix with a detection efficiency of approximately 40% of that of a 3He detector. A maximum count rate of 50 million counts per second (Mcps) is obtained. Using the exclusive function, the center-of-gravity pixel size obtained is 0.4 mm, although the actual pixel size is 3mm. Furthermore, this function also enables a wide area detector in an area of 10 × 10 cm2 using four multi-anode (8 × 8 matrix) photomultiplier tubes. In this case, the pixel size is 0.8mm, although the actual pixel size is 6 mm

    Development of wide area detector for the 2012 model of the 6Li time analyzer neutron detector system

    Get PDF
    A 2012 model 6Li time analyzer neutron detector (LiTA12) system has been developed as a high-count-rate neutron detector. An exclusive function with a center-of-gravity calculation, which not only prevents over-counting due to cross-talk, but also obtains a fine position resolution, has been included. As a highcount-rate detector, this device can detect neutrons with a 3mm position resolution in a detection area of 5×5 cm2 and is arranged as a 16×16 matrix with a detection efficiency of approximately 40% of that of a 3He detector. A maximum count rate of 50 million counts per second (Mcps) is obtained. Using the exclusive function, the center-of-gravity pixel size obtained is 0.4 mm, although the actual pixel size is 3mm. Furthermore, this function also enables a wide area detector in an area of 10 × 10 cm2 using four multi-anode (8 × 8 matrix) photomultiplier tubes. In this case, the pixel size is 0.8mm, although the actual pixel size is 6 mm

    Preliminary experimental results of gas recycling subsystems except carbon dioxide concentration

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    Oxygen concentration and separation is an essential factor for air recycling in a controlled ecological life support system (CELSS). Furthermore, if the value of the plant assimilatory quotient is not coincident with that of the animal respiratory quotient, the recovery of oxygen from the concentrated CO2 through chemical methods will become necessary to balance the gas contents in a CELSS. Therefore, oxygen concentration and separation equipment using Salcomine and O2 recovery equipment, such as Sabatier and Bosch reactors, were experimentally developed and tested

    Influences of dietary lipid and phosphorus levels on retention and excretion of phosphorus and nitrogen in fingerlings red sea bream, Pagrus major

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    A laboratory based 2x3 factorial experiment was conducted for 12 weeks to investigate the influences of dietary lipid and phosphorus (P) levels on retention and excretion of phosphorus and nitrogen (N) in fingerling red sea bream. Two levels of lipid (210 and 260 g/kg) and three levels of phosphorus (17, 14 and 12 g/kgˉ¹) in the dry diets were tested. Duplicate groups of 25 red sea bream (average weight 3.74±0.07 g) per 60L glass tank were fed experimental diets three times a day near to satiation level at 22 to 28°C water temperature. A reduction in dietary fish meal from 500 to 300 g/kg dry diet, corresponding to a supplementation in both dietary lipid and P resulted in significant increase in both P and N retention which resulted in the reduction of their excretion by red sea bream. The overall results of the present study demonstrated that both lipid and phosphorus supplementation are necessary for developing less-polluting feed which in turn, reduce fish meal level in the diet of fingerling red sea bream. Further studies in this regard with different size and age groups of red sea bream are warranted

    Effects of dietary phosphorus and zinc levels on growth artd bone mineralization in fingerlings of rainbow trout, Oncorhynchus mykiss

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    A laboratory based 2 x 2 factorial experiment was conducted to investigate the influences of dietary phosphorus and zinc levels on growth and bone mineralization in fingerlings of rainbow trout for 21 weeks. Two levels of phosphorus (19 and 30 mg/g) and two levels of zinc (55 and 103 Ag/g) in the dry diets were tested. Duplicate tanks of 30 rainbow trout (average weight 1.56 ± 0.24 g) per 60L glass tank were fed experimental diets three times a day to apparent satiation level at 15 to 24°C water temperature. The results of the present study demonstrated that dietary phosphorus supplementation influenced the growth and bone mineralization whereas zinc levels significantly (p<0.05) influenced bone mineralization in rainbow trout. Further investigations in this area with different size and age groups of this fish are broadly needed

    Slow-roll Inflation with the Gauss-Bonnet and Chern-Simons Corrections

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    We study slow-roll inflation with the Gauss-Bonnet and Chern-Simons corrections. We obtain general formulas for the observables: spectral indices, tensor-to-scalar ratio and circular polarization of gravitational waves. The Gauss-Bonnet term violates the consistency relation r = -8n_T. Particularly, blue spectrum n_T > 0 and scale invariant spectrum |8n_T|/r << 1 of tensor modes are possible. These cases require the Gauss-Bonnet coupling function of \xi _{,\phi } \sim 10^8/M_{Pl}. We use examples to show new-inflation-type potential with 10M_{Pl} symmetry breaking scale and potential with flat region in \phi \gtrsim 10M_{Pl} lead to observationally consistent blue and scale invariant spectra, respectively. Hence, these interesting cases can actually be realized. The Chern-Simons term produce circularly polarized tensor modes. We show an observation of these signals supports existence of the Chern-Simons coupling function of \omega _{,\phi } \sim 10^8/M_{Pl}. Thus, with future observations, we can fix or constrain the value of these coupling functions, at the CMB scale.Comment: 21 pages, 5 figure
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