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  • 1995-1999  (30)
  • 1935-1939  (4)
  • 1840-1849  (2)
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 6 (1999), S. 4739-4749 
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The electron beam generated in a self-modulated laser-wakefield accelerator is characterized in detail. A transverse normalized emittance of 0.06 π mm mrad, the lowest ever for an electron injector, was measured for 2 MeV electrons. The electron beam was observed to have a multicomponent beam profile and energy distribution. The latter also undergoes discrete transitions as the laser power or plasma density is varied. In addition, dark spots that form regular modes were observed in the electron beam profile. These features are explained by analysis and test particle simulations of electron dynamics during acceleration in a three-dimensional plasma wakefield. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 624-627 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Diamond, with its high radiation damage resistance, is an attractive alternative to silicon for neutron measurements in next step fusion experiments. A 200-μm-thick type IIa natural diamond with Ti/Au contacts was tested at the LAMPF-WNR facility by time-of-flight neutron energy identification. The crystal, having a carrier lifetime of up to 1 ns, was arranged in a low-energy-resolution, high-sensitivity proton recoil telescope consisting of a polyethylene radiator and a low-energy-proton Teflon filter. This arrangement is similar to the triton burnup monitor of Croft et al. [Rev. Sci. Instrum. 64, 1418 (1993)], where a silicon photodiode was used as a recoil proton detector. The observed sensitivity for 14 MeV neutrons (DT) is (1.25±0.15)×10−3 counts/neutron. However, a high contribution of neutron-induced events in the diamond, mainly carbon (A=12) recoils, was observed. A one-dimensional calculation for the detector response to carbon recoil and proton deposition is compared to the measurements. Poor energy resolution of the diamond detector precludes pulse height discrimination between direct 2.5 MeV neutrons events and proton events corresponding to 14 MeV neutrons. Therefore, an overall DT/DD neutron sensitivity ratio of only ∼6.5 is achieved. This value is much lower than the ratio of 540 reported by Croft et al. in their silicon (A=28) monitor.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 3010-3013 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Reactivities of bimetallic clusters can be controlled by varying their composition, making them potentially valuable as catalysts and for use in elucidating the reactivities of such subnanoscale surfaces. A dual rod laser vaporization source coupled to a fast flow reactor is developed for the study of bimetallic clusters and their reactions. In order to establish the versatility of the technique, the results of studies are presented in which Nb/Al clusters are formed in two plasmas induced by the second harmonic (532 nm photons) of a single Nd:YAG laser and then detected by a quadrupole mass spectrometer. The beam from the laser is split and then focused onto each rod, allowing the mixing ratio within the cluster to vary by altering the laser fluence on each rod. With a low fluence on the Nb rod and a high fluence on the Al rod, an Al rich cluster distribution is formed, NbAlm〈sup ARRANGE="STAGGER"〉− (m=2–20), and Alm〈sup ARRANGE="STAGGER"〉− (m=5–31). By increasing the fluence on the Nb rod and decreasing the fluence on the Al rod, a Nb rich cluster distribution is formed, NbnAlm〈sup ARRANGE="STAGGER"〉− (n=3–8 and m=1–3),NbnOAlm − (n=3–8 and m=1–5), andNbnO− (n=3–8). Additional characterization is also performed on V/Al clusters. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 5516-5521 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Conductivity modulated devices, similar to photoconductors in operation, for use as radiation detectors were fabricated from polycrystalline chemical vapor deposited diamond films. These detectors were designed to operate under extremely high radiation fields with a large dynamic range in both response and speed. Two types of detectors were studied: a parallel-plate device and a surface device (SDT). The radiation used to excite these detectors was minimum ionizing electrons with an energy of 16 MeV and a nominal pulse width of less than 25 ps. The response time of all detectors was less than 45 ps. The sensitivity of the detectors was in the range 10−5–10−6 A/W. Over the operating range of the detectors, signal saturation was not observed because to the signal size was small in comparison to the applied bias voltage. The detectors appeared to be linear with dose and dose rate over two orders of magnitude, and for dose rates up to 1013 rad/s. Long-lived signal decay tails contributed to much less than 1% of the signal. The response of a SDT detector appeared to be independent of the orientation of the detector to the incident beam direction when the excitation source is minimum ionizing. It appears that the dose-rate linearity may be extended to a range greater than 1013 rad/s. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3016-3018 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A quantitative measure of grain-boundary effects on the carrier transport properties in polycrystalline chemical-vapor-deposited diamond has been obtained using a 10-ns hard x-ray excitation source. Two device geometries were used to gain insight into the extent of grain-boundary effects: one having the applied electric field normal and the other parallel to the grain orientation. The applied electric field intensity was varied to adjust the mean-free carrier drift distance. The degradation in the carrier transport properties at an electric field intensity of 10 kV/cm by the grain-boundary appears to be approximately a factor of two in comparison to the intragrain carrier transport.© 1996 American Institute of Physics
    Materialart: Digitale Medien
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  • 6
    ISSN: 1600-0625
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Members of the plakin family of cytolinker proteins integrate filaments into cellula networks and anchor these networks to the plasma membrane. Their importance is supported by the existence of cell and tissue fragility disorders caused by mutations in certain family members. In this study, the human gene encoding desmoplakin (DSP) was characterized and its structure compared with the related family members: plectin, bullous pemphigoid antigen 1 (BPAG1), envoplakin (EVPL) and periplakin (PPL). Sequence analysis of genomic clones was carried out in combination with a PCR-based strategy to define intron-exon border. DSP was mapped using the GB4 radiation hybrid mapping panel to the interval between markers D6S296 and AFM043Xf2, correponding to cytogenetic band 6p24. In addition, the murine gene (DSP) was mapped to mouse chromosome 13 by interspecific backcross mapping. DSP encompasses 45 kb organized into 24 exons and 23 introns, and the pattern of intron-exon borders bears a striking resemblance to other member of the plakin family. Notable features include the fact that a single large exon encodes the entire C-termius of each gene. In contrast, the N-termini comprise numerous smaller exons with conservation of many genses will facilitate their further evaluation as targets of genetic disorders and provide insights into the evolutionary relationships among molecules in this emerging gene family.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1546-170X
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Medizin
    Notizen: [Auszug] Despite the prevalence of γδ T cells in mucosae that are typically colonized by Candida albicans, little is known of the possible role of these cells in resistance to candidiasis. A sharp increase in the number of γδ T cells and macrophages following intraperitoneal ...
    Materialart: Digitale Medien
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  • 8
    facet.materialart.
    Unbekannt
    Berlin : Periodicals Archive Online (PAO)
    Orientalistische Literaturzeitung. 38 (1935) 545 
    ISSN: 0030-5383
    Thema: Allgemeine und vergleichende Sprach- und Literaturwissenschaft. Indogermanistik. Außereuropäische Sprachen und Literaturen , Ethnologie , Geschichte
    Notizen: Besprechungen
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  • 9
    facet.materialart.
    Unbekannt
    Berlin : Periodicals Archive Online (PAO)
    Orientalistische Literaturzeitung. 41 (1938) 255 
    ISSN: 0030-5383
    Thema: Allgemeine und vergleichende Sprach- und Literaturwissenschaft. Indogermanistik. Außereuropäische Sprachen und Literaturen , Ethnologie , Geschichte
    Notizen: Besprechungen
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 159 (1998), S. 0 
    ISSN: 1574-6968
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The purpose of this work was to identify the function of an open reading frame called YBL042, found during the systematic sequencing of Saccharomyces cerevisiae's chromosome II. The YBL042 gene product shows 70% similarity with the uracil permease and the allantoin permease encoded by FUR4 and DAL4, respectively. The mutation constructed by disruption of this ORF is allelic to the FUI1 gene previously described as encoding the uridine permease but not cloned yet. A strain carrying the disrupted allele and a fui1 mutant exhibit the same phenotype as they do not grow on a medium containing uridine as the sole source of pyrimidines and as they are resistant to 10−3 M 5-fluorouridine (5FUI), a toxic analog of uridine. Even though the FUI1 gene has a multicopy suppressor effect on uracil transport, its product does not seem to be involved in this transport, in contrast to the FUR4 gene product which is involved in uridine transport. Moreover, the FUI1 gene product does not play any role in allantoin transport.
    Materialart: Digitale Medien
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