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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 530-533 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Beam position stability was found to be largely affected by the distortion of the storage ring building, especially when the beam emittance was lowered. Building distortion in the horizontal direction was noticed as the diurnal deviation of the orbit circumference. The deviation was measured by reading the amount of rf frequency variation necessary to recover the horizontal central orbit. The deviation of the orbit circumference was interpreted to be induced from the ring floor expansion. Such diurnal expansion of the ring floor was evaluated by using a model simulation that dealt with the distortion of the ring building under thermal stress. To reduce such thermal stress, the rooftop of the building was insulated. The deviation of the ring circumference measured after insulation was reduced to one-half of that measured before. The simulation also gave the same amount of deviations as measured before and after insulation.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 1926-1929 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper describes a new 500 MHz cavity which has a simple damped structure for the 2.0 GeV high-brilliant synchrotron radiation source. The damping of higher-order modes (HOMs) is achieved by large hole beam ducts, a part of which is made of microwave absorber. We have adopted as the microwave absorber a sintered SiC named CERASIC-B manufactured by Toshiba Ceramics Co. Ltd. The latest design of the cavity with CERASIC-B beam ducts is presented in this paper. We have fabricated a prototype model of the cavity. The results of the low power measurement are also reported here. It was confirmed that by using the CERASIC-B beam ducts the Q values of HOMs were strongly damped. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 1910-1912 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Development of a SiC microwave absorber for a damped cavity is presented. The SiC studied has a resistivity of 101–102 Ω cm, which is the expected value to damp higher-order modes (HOMs) in the cavity and also has high thermal conductivity. The absorber is attached to the cavity as a part of the beam duct. Since the SiC duct receives a large amount of energy from the electron (or positron) stored beam, it is very important to estimate the dissipation power in the SiC duct and to design a cooling mechanism. The heat load problem of the SiC duct is discussed and the results of high power testing of the SiC duct are presented. The damping mechanism for HOMs is based on the power dissipation due to the resistivity of SiC. The fine control of the resistivity of SiC in fabrication is very important. The preliminary results on this problem are also presented. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Genes affecting acetylcholine (ACh) levels without influencing choline acetyltransferase activity have been identified in Caenorhabditis elegans. We have examined one such gene, unc-18. We isolated a transposon-insertion allele for unc-18 and used it to clone a genomic region containing the unc-18 locus. The unc-18 location within this region was determined by rescuing the unc-18 mutant phenotype in a germline transformation experiment and identifying transcripts affected by four independent unc-18 mutations. A single-sized poly(A)+ RNA was synthesized from the gene. Expression of the transcript appears to be stage specific: The transcript is found in abundance at the early larval stage but in decreased amounts at the fourth larval and the adult stages. These results show that the unc-18 gene plays a role in development as well as in the kinetics of ACh metabolism.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1507-1512 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: To obtain position-stabilized photon beams from the Photon Factory storage ring, our efforts were concentrated on two directions, one to minimize any disturbances causing the stored beam to move, and the other to suppress undesired beam motion by using feedback systems. This paper concerns one of the most disturbing cases, the diurnal beam position drift. The drift motion was suppressed with a global orbit feedback system, so that photon beam position was kept stable at all the beamlines. At the same time, some disturbances were reduced by investigating the cause and the mechanism of beam motion. The fact that the beam drift motion was closely correlated to the outdoor temperature variations led us to make a model simulation by taking account of the meteorological conditions around the building. It was proved that the building distortion due to the external thermal stress resulted in the diurnal beam motion. To minimize such distortion, it is suggested that one should insulate the building on the rooftop rather than underneath it as is usually done.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1855-1858 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A high-field multipole wiggler (MPW#16), which was composed of hybrid-configured permanent magnets, was completed and installed in the 2.5-GeV Photon Factory (PF) storage ring as the third insertion device. Compared to the synchrotron radiation from the bending magnet on the PF ring, the radiation from the MPW#16 has two orders higher brilliance in the x-ray region and three orders higher in the vacuum ultraviolet region. The stable operation of the storage ring coupled with the MPW#16 has been confirmed through various machine studies.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A new VUV beamline at the Photon Factory ring that is designed to accept radiation emitted from an undulator is described. The characteristics of the undulator and all parts of the beamline; a front end, a mirror system, and two monochromators, are described in detail. The characteristics of optical elements in the beamline are also shown.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The photon beam radiating from the position-stabilized storage ring tended to show large vertical drift at some beamlines. It had earlier been pointed that the beam drift might be due to the local floor displacement which was caused by the thermal distortion of the storage ring building. An estimate of the floor displacement was made by using a simulation model which takes into account the thermal stress due to the sunbeam heating of the buildings, and it seemed to give an explanation for the amount of photon-beam displacement. This raised a question whether the local floor movement is fully responsible for the apparent displacement of the photon beam. Detailed study was primarily carried out for beamline 4. First, the level of the beamline was surveyed and found to be small compared with the amount of beam displacement actually observed. Second, when beam displacement was measured with respect to two independent frames of reference located at the upstream and downstream ends of the beamline, no difference was found between the two. Both the level survey and the displacement measurement led us to conclude that the large photon-beam drift was produced not by the local floor movement, but by the beam itself.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Degenerate oligonucleotide primers based on the amino acid sequences of gibberellin (GA) 20-oxidases from pumpkin and Arabidopsis were used in nested polymerase chain reactions to generate an internal cDNA fragment from rice (Oryza satiya L.) seedlings. Using this fragment as a probe, a full-length cDNA (pOs20ox) was isolated from a cDNA library constructed from rice seedlings. The deduced amino acid sequence of Os20ox showed good identity (42–55%) with the GA 20-oxidases from pumpkin and Arabidopsis. Recombinant Os20ox protein, produced in Escherichia coli, catalyzed the conversion of GA12 and GA53 to GA9 and GA20, respectively. In contrast to the enzyme from immature pumpkin seeds, the recombinant rice GA 20-oxidase did not produce the tricarboxylic acids GA25 and GA17 from GA12 and GA53, respectively. The conversion rate of GA53 was higher than that of GA12. which is consistent with the relatively high abundance of 13-hydroxylated GAs in rice seedlings. Os20ox mRNA accumulated at higher levels in seedlings of two GA-deficient dwarf mutants than in normal plants. Treatment with uniconazole-P. an inhibitor of GA biosynthesis, increased abundance of the mRNA, while exogenously applied GA3 decreased it. These results suggest that the expression of the Os20ox gene is regulated by the level of physiologically active GA.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Bradford : Emerald
    International journal of numerical methods for heat & fluid flow 15 (2005), S. 863-871 
    ISSN: 0961-5539
    Quelle: Emerald Fulltext Archive Database 1994-2005
    Thema: Maschinenbau
    Notizen: Purpose - To introduce an efficient two-dimensional numerical procedure for a three-dimensional internal flow through a complex passage with a small depth, in which the viscous effects from upper and lower walls are significant. Design/methodology/approach - A set of two-dimensional governing equations has been derived by integrating the full three-dimensional Navier-Stokes equations over the depth. Then, this set of the governing equations has been discretized using a finite volume method. Simple algorithm and quick scheme are used to solve the resulting discretized equations. Findings - A numerical experiment conducted to investigate the oscillation mechanism of a feedback fluidic oscillator reveals that the feedback passage plays an important role of transmitting the pressure rise to the control port, which triggers the jet stream to deflect towards the opposite side wall in the reaction region. Comparison of the prediction and experiment substantiates the validity of the present numerical procedure. Originality/value - The two-dimensional numerical procedure, proposed in this study, will be used by researchers and practitioners to investigate various kinds of complex passages with a small depth. Especially, those who are interested in fluidic devices may find it extremely convenient to conduct numerical experiments.
    Materialart: Digitale Medien
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