Expression of Brain-Type Fatty Acid-Binding Protein (fabp7) in Medaka During Development

Fatty acid-binding proteins (FABPs) belong to a multigene family of small intracellular proteins that bind hydrophobic ligands. Recent studies have indicated that FABP7 plays important roles in neurogenesis or neuronal migration in vertebrates. In this study, we isolated cDNA and the genomic fragment containing the fabp7 gene for medaka fish and examined the expression of the medaka fabp7 gene through the development of their central nervous system (CNS). The medaka fabp7 gene consists of four exons in approximately 1 kb of the genomic region. Its deduced amino acid sequence exhibits over 80% identity with those of other higher vertebrates. In situ hybridization analysis demonstrated that fabp7-positive cells first appear at stage 22 in a small dorsal domain of the retina, dorsal diencephalon, and rhombencephalon, then expand to the entire CNS including the retina and spinal cord. In addition, we generated two lines of transgenic medaka with 1.7 kb upstream of the fabp7 gene combined with the enhanced-green fluorescence protein (EGFP) gene. The spatio-temporal expression patterns of EGFP in these animals were consistent with the results of in situ hybridization analysis. The result of our reporter assays with a series of truncated fabp7 promoters suggested that POU elements play a role in fabp7expression in medaka as well as in other vertebrates. Our transgenic animal will contribute to clarifying the role of FABP7 in the development of CNS

1 mA Stable Energy Recovery Beam Operation with Small Beam Emittance

A compact energy-recovery linac (cERL) have been operating since 2013 at KEK to develop critical components for ERL facility. Details of design, construction and the result of initial commissioning are already reported*. This paper will describe the details of further improvements and researches to achieve higher averaged beam current of 1 mA with continuous-wave (CW) beam pattern. At first, to keep the small beam emittance produced by 500 kV DC-photocathode gun, tuning of low-energy beam transport is essential. Also, we found some components degrades the beam quality, i.e., a non-metallic mirror which disturbed the beam orbit. Other important aspects are the measurement and mitigation of the beam losses. Combination of beam collimator and tuning of the beam optics can improve the beam halo enough to operate with 1 mA stably. The cERL has been operated with beam energy at 20 MeV or 17.5 MeV and with beam rep-rate of 1300 MHz or 162.5 MHz depending on the purpose of experiments. In each operation, the efficiency of the energy recovery was confirmed to be better than 99.9 %.10th International Particle Accelerator Conferenc

Construction and commissioning of the compact energy-recovery linac at KEK

Energy-recovery linacs (ERLs) are promising for advanced synchrotron light sources, high-power free electron lasers (FELs), high-brightness gamma-ray sources, and electron–ion colliders. To demonstrate the critical technology of ERL-based light sources, we have designed and constructed a test accelerator, the compact ERL (cERL). Using advanced technology that includes a photocathode direct current (DC) electron gun and two types of 1.3-GHz-frequency superconducting cavities, the cERL was designed to be capable of recirculating low emittance (1 mm mrad) and high average-current (10 mA) electron beams while recovering the beam energy. During initial commissioning, the cERL demonstrated successful recirculation of high-quality beams with normalized transverse emittance of 0.14 mm mrad and momentum spread of 1.2 10−4 (rms) at a beam energy of 20 MeV and bunch charge below 100 fC. Energy recovery in the superconducting main linac was also demonstrated for high-average-current continuous-wave beams. These results constitute an important milestone toward realizing ERL-based light sources

The First Beam Recirculation and Beam Tuning in the Compact ERL at KEK

Superconducting(SC)-linac-based light sources, which can produce ultra-brilliant photon beams in CW operation, are attracting worldwide attention. In KEK, we have been conducting R&D; efforts towards the energy-recovery-linac(ERL)-based light source* since 2006. To demonstrate the key technologies for the ERL, we constructed the Compact ERL (cERL)** from 2009 to 2013. In the cERL, high-brightness CW electron beams are produced using a 500-kV photocathode DC gun. The beams are accelerated using SC cavities, transported through a recirculation loop, decelerated in the SC cavities, and dumped. In the February of 2014, we succeeded in accelerating and recirculating the CW beams of 4.5 micro-amperes in the cERL; the beams were successfully transported from the gun to the beam dump under energy recovery operation in the main linac. Then, precise tuning of beam optics and diagnostics of beam properties are under way. We report our experience on the beam commissioning, as well as the results of initial measurements of beam properties

Achievements of KEKB

The machine commissioning of KEKB started in December 1998 and its operation was terminated at the end of June 2010 to upgrade KEKB to SuperKEKB. In this paper, we summarize the history of KEKB and show the achievements made there