We present results of a survey for giant Lyα blobs (LABs) at z= 3 with Subaru/Suprime‐Cam. We obtained Lyα imaging at z= 3.09 ± 0.03 around the SSA22 protocluster and in several blank fields. The total survey area is 2.1 deg2, corresponding to a comoving volume of 1.6 × 106 Mpc3. Using a uniform detection threshold of 1.4 × 10−18 erg s−1 cm−2 arcsec−2 for the Lyα images, we construct a sample of 14 LAB candidates with major‐axis diameters larger than 100 kpc, including five previously known blobs and two known quasars. This survey triples the number of known LABs over 100 kpc. The giant LAB sample shows a possible ‘morphology–density relation’: filamentary LABs reside in average density environments as derived from compact Lyα emitters, while circular LABs reside in both average density and overdense environments. Although it is hard to examine the formation mechanisms of LABs only from the Lyα morphologies, more filamentary LABs may relate to cold gas accretion from the surrounding intergalactic medium (IGM) and more circular LABs may relate to large‐scale gas outflows, which are driven by intense starbursts and/or by active galactic nucleus activities. Our survey highlights the potential usefulness of giant LABs to investigate the interactions between galaxies and the surrounding IGM from the field to overdense environments at high redshift.

Deep narrow-band (NB359) imaging with Subaru telescope by Iwata et al. has detected a surprisingly strong Lyman continuum (LyC; ∼900 Å in the rest frame) from some Lyman α emitters (LAEs) at z = 3.1. However, the possibility of a redshift misidentification by the previous spectroscopic studies due to a narrow wavelength coverage cannot be rejected. Here we present the results of a new technique, the deep spectroscopy, in which we covered 4000-7000 Å with VLT/VIMOS and Subaru/FOCAS for the eight LAEs detected in NB359. All the eight objects have only one detectable emission line around 4970 Å , which is most likely to be Lyα at z = 3.1, and thus, the objects are certainly LAEs at the redshift. However, five of them show a ∼0.8 arcsec spatial offset between the Lyα emission and the source detected in NB359. No indications of the redshifts of the NB359 sources are found although it is statistically difficult that all the five LAEs have a foreground object accounting for the NB359 flux. The rest three LAEs show no significant offset from the NB359 position. Therefore, we conclude that they are truly LyC-emitting LAEs at z = 3.1. We also examine the stellar population which simultaneously accounts for the strength of the LyC and the spectral slope of non-ionizing ultraviolet of the LAEs. We consider the latest statistics of Lyman limit systems to estimate the LyC optical depth in the intergalactic medium (IGM) and an additional contribution of the bound-free LyC from photoionized nebulae to the LyC emissivity. As a result, we find that stellar populations with metallicity Z ≥ 1/50 Z can explain the observed LyC strength only with a very top-heavy initial mass function (IMF; m ∼ 50 M ). However, the critical metallicity for such an IMF is expected to be much lower. A very young (∼1 Myr) and massive (∼100 M ) extremely metal-poor (Z ≤ 5 × 10 −4 Z ) or metal-free (so-called Population III) stellar population can reproduce the observed LyC strength. The required mass fraction of such 'primordial' stellar population is ∼1-10 per cent in total stellar mass of the LAEs. We also present a possible evolutionary scenario of galaxies emitting strong LyC and implications of the primordial stars at z ∼ 3 for the metal enrichment in the intergalactic medium and for the ionizing background and reionization.

We present the discovery of a candidate of giant radio‐quiet Lyα blob (RQLAB) in a large‐scale structure around a high‐redshift radio galaxy (HzRG) lying in a giant Lyα halo B3 J2330+3927 at redshift z= 3.087. We obtained narrow‐ and broad‐band imaging around B3 J2330+3927 with Subaru/Suprime‐Cam to search for Lyα emitters (LAEs) and absorbers (LAAs) at redshift z= 3.09 ± 0.03. We detected candidate 127 LAEs and 26 LAAs in the field of view of 31 × 24 arcmin2 (58 × 44 comoving Mpc). We found that B3 J2330+3927 is surrounded by a 130 kpc Lyα halo and a large‐scale (∼60 × 20 comoving Mpc) filamentary structure. The large‐scale structure contains one prominent local density peak with an overdensity of greater than 5, which is 8 arcmin (15 comoving Mpc) away from B3 J2330+3927. In this peak, we discovered a candidate 100 kpc RQLAB. The existence of both types of Lyα nebulae in the same large‐scale structure suggests that giant Lyα nebulae need special large‐scale environments to form. On smaller scales, however, the location of B3 J2330+3927 is not a significant local density peak in this structure, in contrast to the RQLAB. There are two possible interpretations of the difference of the local environments of these two Lyα nebulae. First, RQLAB may need a prominent (δ∼ 5) density peak of galaxies to form through intense starbursts due to frequent galaxy interactions/mergers and/or continuous gas accretion in an overdense environment. On the other hand, Lyα halo around HzRG may not always need a prominent density peak to form if the surrounding Lyα halo is mainly powered by its radio and active galactic nucleus activities. Alternatively, both RQLAB and Lyα halo around HzRG may need prominent density peaks to form but we could not completely trace the density of galaxies because we missed evolved and dusty galaxies in this survey.

We present results of a survey of Lyα emitters (LAEs) at z = 6.5 which is thought to be the final epoch of the cosmic re-ionization. In a ≈530 arcmin 2 deep image of the SSA22 field taken through a narrow-band filter NB912 installed in the Subaru/Suprime-Cam, we have found only 14 LAE candidates with L Lyα 3 × 10 42 erg s −1 . Even applying the same colour selection criteria, the number density of the LAE candidates is a factor of 3 smaller than that found at the same redshift in the Subaru Deep Field (SDF). Assuming the number density in the SDF is a cosmic average, the probability to have a number density equal to or smaller than that found in the SSA22 field is only 7 per cent if we consider fluctuation by the large-scale structure (i.e. cosmic variance) and Poisson error. Therefore, the SSA22 field may be a rare void at z = 6.5. On the other hand, we have found that the number density of i -drop galaxies with 25.5 < z < 26.0 in the SSA22 field agrees well with that in the SDF. If we consider a scenario that a larger neutral fraction of intergalactic hydrogen, x H I , in the SSA22 field obscures a part of Lyα emission, x H I in the SSA22 field should be about two times larger than that in the SDF. This can be translated into x H I < 0.9 at z = 6.5 in the SSA22 field. A much larger survey area than previous ones is required to overcome a large fluctuation reported here and to obtain a robust constraint on x H I at the end of the re-ionization from LAEs.

Thiazole derivatives Thiazole derivatives R 0260 Facile Synthesis of 2,5-Diarylthiazoles via Palladium-Catalyzed Tandem C-H Substitutions. Design of Tunable Light Emission and Liquid Crystalline Characteristics. -(MORI*, A.; SEKIGUCHI, A.; MASUI, K.; SHIMADA, T.; HORIE, M.; OSAKADA, K.; KAWAMOTO, M.; IKEDA, T.; J. Am. Chem. Soc. 125 (2003) 7, 1700-1701; Chem. Resour. Lab., Tokyo Inst. Technol., Yokohama 226, Japan; Eng.) -Nuesgen 22-120

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Artificial heart pumps have attracted the attention of researchers around the world as an alternative to the organ used in cardiac transplantation. Conventional centrifugal pumps are no longer considered suitable for long-term application because of the possibility of occurrence of blood leakage and thrombus formation around the shaft seal. To overcome this problem posed by the shaft seal in conventional centrifugal pumps, the magnetically suspended centrifugal pump has been developed; this is a sealless rotor pump, which can provide contact-free rotation of the impeller without leading to material wear. In Europe, clinical trials of this pump have been successfully performed, and these pumps are commercially available. One of the aims of our study is to numerically examine the internal flow and the effect of leakage flow through the gap between the impeller and the pump casing on the performance of the pump. The results show that the pressure head increases compared with the pump without a gap for all flow rates because of the leakage of the fluid through the gap. It was observed that the leakage flow rate in the pump is sufficiently large; further, no stagnant fluid or dead flow regions were observed in the pump. Therefore, the present pump can efficiently enhance the washout effect.

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