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  • 1
    ISSN: 1432-1106
    Keywords: Hierarchical processing ; Sensory cortex ; Reciprocal connections ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The prevalence of reciprocal connections in the cerebral cortex indicates that they play a fundamental role in the processing of sensory information. We have investigated the laminar termination patterns of such paired connections between different visual cortical areas of the rat, and have found two basic projection types: one which includes layer 4 and a second which includes layer 1 and avoids layer 4. The projections from primary visual cortex (area 17) to extrastriate visual cortical targets in the cytoarchitectonical areas 18a and 18b, and from 18a to a site in 18b, are of the first type. In contrast, the return projections from 18a and 18b to area 17 and from 18b to 18a, are of the second type. Thus each pair of connections has one element of each type, giving every circuit a nearly identical asymmetric structure. These laminar patterns resemble those of forward and feedback connections in primate cortex, indicating that cortico-cortical connectivity patterns are highly conserved through evolution, and that, as in monkeys, these connections define a hierarchical organization of areas in rat visual cortex.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 1448-1456 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Described here is the design and construction of a pulse-power generator capable of discharging at high repetition rates. It consists of eight triaxial Blumleins stacked in series at one end. These lines are charged in parallel and synchronously commuted with a single thyratron at the other end to produce an open circuit voltage across a stack of six times the charging voltage. An x-ray diode has been constructed and matched to this pulse-power source making possible the emission of an average bremsstrahlung exposure rate of 17 R/S from a sequence of 40-ns pulses. When operated at 60-kV charging voltage, direct spectral measurements show the output to be a true continuum, peaking at intensities in excess of 5×108 photons/keV/shot and containing useful intensities of photons having energies of 300 keV.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 2062-2064 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this work we report the first observation of the screening effect in large-area, cold-cathode diodes. A framing camera was used to observe the formation of emission centers (ECs) on a 200 cm2 velvet emitter. The density of ECs increased as a function of applied magnetic field as predicted. The current per EC decreased as the magnetic field was increased. These phenomena suggest methods of increasing the spatial and temporal uniformity of high-power electron beams.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0851
    Keywords: Lewis lung carcinoma ; TGFβ ; Bone marrow ; Immunosuppressor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Normal bone marrow cells become immunosuppressive when cultured with supernatants of metastatic Lewis lung carcinoma (LLC-LN7) cells. The suppressorinducing activities in the LLC-LN7 supernatants are interleukin-3 and granulocyte/macrophage-colony-stimulating factor. In the present study, the mechanisms by which these induced suppressor cells (LLCsup-BM) mediate their immunosuppression were investigated. The suppression by LLCsup-BM of splenic concanavalin CA blastogenesis was not dependent on cell contact since immunosuppression occurred regardless of whether the LLCsup-BM were separated from the responder spleen cells by a permeable membrane or if the LLCsup-BM were cocultured with the spleen cells. Culture supernatants of LLCsup-BM also inhibited T cell blastogenesis, being more suppressive than were supernatants of control bone marrow cells, which had been precultured with medium. The suppression by the soluble inhibitors elaborated from the LLCsup-BM was not restricted to the inhibition of T cell function as the supernatants also inhibited the natural killer activity of normal spleen cells. Studies to determine the identity of the suppressive activity produced by the LLCsup-BM showed increased levels of transforming growth factor β (TGFβ) in their supernatants. Immunosuppressive bone marrow and spleen cells obtained from mice bearing metastatic LLC-LN7 tumors also secreted more TGFβ than did the cells obtained from normal mice. When anti-TGFβ antibodies were added to the LLCsup-BM supernatants, the suppressive activity was diminished. These results suggest that the LLCsup-BM mediate at least part of their immunosuppression through production of TGFβ.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Plasma destruction of toxins, and volatile organic compounds in particular, from gas streams is receiving increased attention as an energy efficient means to remediate those compounds. In this regard, remediation of trichloroethylene (TCE) in silent discharge plasmas has been experimentally and theoretically investigated. We found that TCE can be removed from Ar/O2 gas streams at atmospheric pressure with an energy efficiency of 15–20 ppm/(mJ/cm3), or 2–3 kW h kg−1. The majority of the Cl from TCE is converted to HCl, Cl2, and COCl2, which can be removed from the gas stream by a water bubbler. The destruction efficiency of TCE is smaller in humid mixtures compared to dry mixtures due to interception of reactive intermediates by OH radicals.
    Type of Medium: Electronic Resource
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