We present the results of a survey for Lyα emitters at z ≈ 5.7 based on optical narrow-band (λ c = 8150 Å and ∆λ = 120 Å), and broad-band (B, R C , I C , and z ′ ) observations of the field surrounding the high redshift quasar, SDSSp J104433.04−012522.2, on the 8.2 m Subaru Telescope with the Subaru Prime Focus Camera, Suprime-Cam. This survey covers a sky area of ≈ 720 arcmin 2 and a co-moving volume of ≃ 2 × 10 5 h −3 0.7 Mpc 3 . We have found 20 candidates of Lyα emitters at z ≈ 5.7 with ∆z ≈ 0.1. Two of them have been confirmed star-forming galaxies at z = 5.655 and z = 5.687 from our follow-up optical spectroscopy. We discuss star-formation properties of the 20 objects from a statistical point of view. Our survey leads to a new estimate of the star formation rate density at z ≈ 5.7, ∼ 1.2 × 10 −3 h 0.

We have carried out a deep imaging survey for Hα emitting galaxies at z ≈0.24 using a narrowband filter tuned with the redshifted line. The total sky area covered is 706 arcmin 2 within a redshift range from 0.234 to 0.252 (δz=0.018). This corresponds to a volume of 3.9×10 3 Mpc 3 when Ω matter = 0.3, Ω Λ = 0.7, and H 0 =70 km s −1 Mpc −1 are adopted. We obtain a sample of 348 Hα emitting galaxies whose observed emission-line equivalent widths are greater than 12 Å. We find an extinction-corrected Hα luminosity density of 10 39.65 +0.08 −0.12 ergs s −1 Mpc −3 . Using the Kennicutt relation between the Hα luminosity and star formation rate, the star formation rate density in the covered volume is estimated as 0.036 +0.006 −0.012 M ⊙ yr −1 Mpc −3 . This value is higher by a factor of 3 than the local SFR density.

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We present an optical multicolor-imaging study of the galaxy cluster A521 at z ¼ 0:25, using Suprime-Cam on the Subaru Telescope, covering an area of 32 0 Â 20 0 (9:4 Â 5:8 h À2 50 Mpc 2 at z ¼ 0:25). Our imaging data taken with both a narrowband filter, NB816 (k 0 ¼ 8150 Å and Ák ¼ 120 Å ), and broadband filters, B; V ; R C ; i 0 , and z 0 , allow us to find 165 H emitters. We obtain the H luminosity function (LF) for the cluster galaxies within 2 Mpc; the Schechter parameters are ¼ À0:75 AE 0:23, Ã ¼ 10 À0:45 to 10 À0.05 Mpc À3 , and L Ã ¼ 10 41:86 to 10 42.2 ergs s À1 . Although the faint-end slope is consistent with that of the local cluster H LFs, the characteristic luminosity L Ã is about 6 times (or %2 mag) brighter. This strong evolution implies that A521 contains more active star-forming galaxies than the local clusters, being consistent with the observed Butcher-Oemler effect. However, the bright L Ã of A521 may be, at least in part, due to the dynamical condition of this cluster.

We have investigated whether low-dose total-body X irradiation could suppress the development of lymphoma in AKR mice. Male mice were irradiated with 5 cGy three times a week or 15 cGy two times a week from 11 weeks of age for 40 weeks. The incidences of lymphoma were 80.5% in sham-irradiated mice, 67.5% in mice irradiated with 5 cGy three times a week and 48.6% in mice irradiated with 15 cGy twice a week. Incidence of lymphoma was significantly reduced by irradiation with 15 cGy twice a week (P = 0.006). The mean survival time was significantly prolonged from 283 +/- 3 days in control mice to 316 +/- 10 days in mice irradiated with 15 cGy twice a week (P = 0.008) and to 309 +/- 14 days in mice irradiated with 5 cGy three times a week (P = 0.040). Because about 80% of male AKR mice die of lymphoma, it is likely that the prolonged life span observed in the irradiated mice is due to the reduced incidence of lymphoma.