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  • 1
    Electronic Resource
    Electronic Resource
    Antarctic marine life under the McMurdo Ice Shelf at White Island: A link between nutrient influx and seal population (1984)
    Springer
    Polar biology 2 (1984), S. 229-231 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Throughout 1981, the first routine collections of a variety of fish were made under the McMurdo Ice Shelf near White Island, Antarctica. Estimates of their local biomass were calculated using food consumption patterns of resident seals. Since no significant primary production occurs at White Island, the resident fauna must be maintained by a large nutrient influx from the Ross Sea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263629
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  • 2
    Electronic Resource
    Electronic Resource
    Nonpositive curvature of blow-ups (1998)
    Springer
    Selecta mathematica 4 (1998), S. 491-547 
    Details
    ISSN: 1420-9020
    Keywords: Key words. Aspherical, blow up, hyperplane arrangement, zonotope.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000290050039
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  • 3
    Electronic Resource
    Electronic Resource
    Central nervous system control of mucous gland secretion from frog skin (1979)
    Springer
    Cellular and molecular life sciences 35 (1979), S. 1339-1339 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Surface electrical stimulation of the diencephalic roof of the frog,Rana berlandieri forreri, brain initiates integumental mucous gland secretion which is abolished by pithing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01963995
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of the ugatA gene of Ustilago maydis, isolated by homology to the gatA gene of Aspergillus nidulans (1996)
    Springer
    Current genetics 29 (1996), S. 360-369 
    Details
    ISSN: 1432-0983
    Keywords: Key words Ustilago maydis ; GABA aminotransferase ; Heterologous expression ; Sequence conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A gene encoding a putative GABA aminotransferase (ugatA) was isolated from the basidiomycete Ustilago maydis via heterologous hybridization to the GABA aminotransferase gene (gatA) of Aspergillus nidulans . The derived amino-acid sequence of ugatA shows strong identity throughout the protein to the GABA aminotransferase enzymes from A. nidulans and Saccharomyces cerevisiae. Northern analysis in U. maydis indicated that the ugatA transcript is inducible by the ω-amino acids GABA and β-alanine, and is not subject to nitrogen catabolite repression. With the use of ugatA promoter-lacZ fusion constructs, it was demonstrated that the removal of sequences located approximately 250 bp 5′ to the translational start site of ugatA (including multiple copies of a 7-bp direct repeat) resulted in the loss of induction by ω-amino acids. While the ugatA gene under the control of the A. nidulans gatA promoter was able to fully complement a gatA - phenotype in A. nidulans, the full-length ugatA gene was not, suggesting a lack of expression from the U. maydis promoter in A. nidulans. A U. maydis strain with a gene disruption at the ugatA locus showed decreased growth on β-alanine as a sole nitrogen source, but was able to grow on GABA as a sole nitrogen source, indicating an alternative pathway for the utilization of GABA in U. maydis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002940050057
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  • 5
    Electronic Resource
    Electronic Resource
    The Aspergillus nidulans gltA gene encoding glutamate synthase is required for ammonium assimilation in the absence of NADP-glutamate dehydrogenase (1999)
    Springer
    Current genetics 34 (1999), S. 467-471 
    Details
    ISSN: 1432-0983
    Keywords: Key wordsAspergillus nidulans ; Ammonium assimilation ; Glutamate synthase ; Gene inactivation ; Glutamate dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mutants of Aspergillus nidulans lacking NADP-glutamate dehydrogenase activity grow more poorly than wild-type strains on ammonium as a sole nitrogen source. The leaky growth of these mutants is indicative of an alternative pathway of ammonium assimilation and glutamate biosynthesis. We have PCR-amplified a portion of the A. nidulans gene encoding glutamate synthase and used this sequence to inactivate the genomic copy. This gene, designated gltA, was found to be dispensable for growth on ammonium in the presence of NADP-glutamate dehydrogenase activity. However, a strain carrying the gltA inactivation together with an NADP-glutamate dehydrogenase structural gene mutation (gdhA) was unable to grow on ammonium or on nitrogen sources metabolized via ammonium. The gltA gene was located to linkage group V of the A. nidulans genetic map.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002940050421
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  • 6
    Electronic Resource
    Electronic Resource
    Recurrent inhibition: Its influence upon transduction and afferent discharges in slowly-adapting stretch receptor organs (1979)
    Springer
    Biological cybernetics 33 (1979), S. 167-178 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The crayfish stretch receptor organs provide the opportunity to study recurrent inhibition (RI) in pure experimental conditions. The slowly adapting organ (SAO) from the cephalothoraxabdomen joint of Procambarus darkii was isolated and its length set by anchoring one end and clamping the other with a movable forceps. Each impulse from the SAO triggered a shock to the common inhibitory fiber, after an adjustable delay called “phase”. Thus, RI acted upon the SAO. Under steady length conditions, the discharge rate with RI was proportional to the spontaneous discharge rate (i.e. to that without RI), and negatively correlated to the ratio of the phase to the spontaneous interspike interval. Under dynamic conditions, with the SAO submitted to under 0.3 mm length variations, sine-like with or without “white” noise, and periodic at 0.2, 1.0, or 3.0 cps, the effect of RI was basically the same in all conditions. While the lower rates of discharge were unchanged, the higher rates were reduced: thus the overall sensitivity of the SAO was decreased. The RI also decreased the discharge variability at the low rates; variability remained unaffected at the high rates. The general form of the response of the SAO was unaffected by RI, as indicated by displays of rate versus length, of rate versus velocity, or of change in rate versus velocity: only the widness of the loops changed. The effects of RI were compared to those of randomly arriving, Poisson-like IPSP's at the same overall rate: the latter did not exhibit the same dependence on the SAO firing rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337295
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  • 7
    Electronic Resource
    Electronic Resource
    Identification of vortex motions in turbulent mixing of choked jets (1988)
    Springer
    Experiments in fluids 6 (1988), S. 335-343 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A specially adapted schlieren system is used to generate fluctuating signals which respond strongly to large scale coherent components of a turbulent mixing jet flow and which have a relatively reduced response to random disturbances. The schlieren signals also provide a direct indication of the presence of vortex-like structures in the turbulent mixing layers by virtue of the phase relationship of the schlieren signals to the pressure field. This system gives a clear resolution of the fluctuating periodic effects associated with vortex structures in the flow from a choked convergent nozzle. It has thus been possible to determine that vortex-like eddies are associated with the feedback screech mechanism, and also generate periodic disturbances due to their passage through the diamond shaped wave structure in the flow. The regular disturbances in the flow move at 0.77 of the fully expanded flow velocity. Phase spectral observations demonstrate clearly the vortex like structure of coherent disturbances in the flow by virtue of the quadrature phase relation between the schlieren and microphone signals. Movement of the sensing microphone in the pressure field external to the flow shows disturbance propagation at the acoustic velocity, and also shows that disturbances at Strouhal numbers above 0.7 emanating from the inner mixing zone can be identified by an additional time delay to reach the microphone and only influence the microphone when it is located downstream of the flow sensing schlieren system due to confinement of pressure disturbances within Mach cones of the flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00538825
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  • 8
    Electronic Resource
    Electronic Resource
    Laser velocimetry measurements in a laboratory vaned diffuser (1990)
    Springer
    Experiments in fluids 9 (1990), S. 33-42 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Laser velocimetry measurements were made within a laboratory radial vaned diffuser with three different blade configurations. Measurements were made through passages with four, six and eight blades installed at off design conditions. Also, in the eight blade diffuser measurements were made between the blade passage exit and diffuser exit so that the complete secondary flow could be defined. The flow was found to separate from the blades and form large separation zones. The separation zones consisted primarily of two vortices rotating in opposite directions. At the passage exit the separation region encompassed 23% of the circumferential area for the four blade diffuser, 45% for the six blade and 40% in the eight blade diffuser. Separation occurred at 23%, 27% and 50% from the leading edge of the blades for the 4, 6 and 8 bladed diffusers, indicating that more blades better controlled the separation. Turbulence intensities ranged from approximately 5% to 15% in the primary flow and reached a few hundred percent in the secondary flow within the separation regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00575333
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  • 9
    Electronic Resource
    Electronic Resource
    Olivine-normative dolerite dikes from western South Carolina: Mineralogy, chemical composition and petrogenesis (1985)
    Springer
    Contributions to mineralogy and petrology 90 (1985), S. 386-400 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract This investigation describes five Mesozoic dolerite dikes which intrude Paleozoic metamorphic and igneous rocks of the Inner Piedmont of western South Carolina. The dikes are vertical or nearly so and strike approximately N40° W. Three major northeast-trending faults also occur in the study area. Left lateral displacement of one dolerite is documented at a locality near Cleveland, South Carolina. Elsewhere, several of the dolerite dikes appear to terminate at or near the faults. — The dolerite dikes have subophitic to microporphyritic textures and consist principally of plagioclase (generally An70–80), olivine (dominantly Fo80–90) and augite with subordinate pigeonite, titanomagnetite, chromite and brown, partly glassy mesostasis. In one dike pyroxene compositions trend from augite to ferroaugite in contrast to an augite→subcalcic augite→pigeonite trend characteristic of the other dolerites. The contrasting trends primarily result from differences in SiO2 abundance in the dolerite magmas. — Major and trace element analyses indicate the presence of two different olivine-normative dolerite magma types. The two magma types are not related by near surface crystal fractionation. Models for genesis of the olivine-normative dolerite magmas by partial melting of a plagioclase peridotite upper mantle source region are presented. The models require that the source region be enriched in LREE and incompatible elements such as Rb, Ba, Hf and Th relative to Cl chondritic abundances. One magma type appears to represent a primary dolerite magma that ascended from the source region with little subsequent compositional change. The second magma type most likely experienced assimilation of clinopyroxene-garnet (eclogite) during ascent, thereby acquiring a REE pattern with a less steep negative slope for the LREE and a slight positive slope in the HREE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384717
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  • 10
    Electronic Resource
    Electronic Resource
    Evaluation of fractal dimension for mixing and combustion by the schlieren method (1996)
    Springer
    Experiments in fluids 21 (1996), S. 248-258 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The evaluation of fractal dimension values from schlieren flow images has been investigated. It was found for passive mixing heated jet flows that a value of 2.31, close to that obtained by tomographic imaging, was obtained. For turbulent diffusion flames a value of 2.40 was obtained, and this increased slightly with axial movement and with acoustic excitation of the flame. Broadly counteracting effects due to the transverse differentiation and integration along the imaging beam inherent in the schlieren method was found to arise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00190674
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