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  • 1
    Electronic Resource
    Electronic Resource
    Retinoic acid in the anteroposterior patterning of the zebrafish trunk (1995)
    Springer
    Development genes and evolution 205 (1995), S. 103-113 
    Details
    ISSN: 1432-041X
    Keywords: Retinoic acid ; Axis formation ; Disulfiram ; Notochord ; Zebrafish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Retinoic acid has been linked to pattern formation in the vertebrate anteroposterior axis. This report describes the spatial and temporal distributions of both endogenous retinoic acid and retinoic acid synthase activity along the anteroposterior axis of neurulating zebrafish embryos, as detected by a transient transgenic assay and by a zymography bioassay. Both retinoic acid levels and synthase activity were found to be highest in anterior regions of the trunk at all of the stages which were analysed. The drug disulfiram inhibited retinoic acid synthase activity in the zebrafish trunk both in vitro and in vivo, and reduced retinoic acid levels in vivo. Disulfiram treatment of neurulating embryos resulted in larvae with hypertrophic wavy notochords, shortened spinal cords and deformed pectoral fins. The results support the hypothesis that retinoic acid plays a role in the coordination of axial patterning at the developing node/zone of involution, as well as in the subsequent development of anterior trunk structures such as the fins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357756
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  • 2
    Electronic Resource
    Electronic Resource
    Comments on the Role of H2S in the Chemistry of Earth's Early Atmosphere and in Prebiotic Synthesis (1998)
    Springer
    Journal of molecular evolution 47 (1998), S. 127-132 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Prebiotic atmospheres — H2S — CO2— Sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract: Free energy calculations and experimental measurements have been used to show that H2S/CO2 mixtures outgassing from a prebiotic Earth's crust would have produced a reducing gas mixture containing CO, H2, H2O, and S x as principal components. Due to rapid recombination of H2, CO, and S x to H2S and CO2 on cooling from a high temperature to ambient conditions, reducing components would have been retained only if efficient quenching of the reduced gas mixture had been possible. Consequently, subsea vents or vents with efficient infusion of water would have been ideal sites for retention of reduced species and for prebiotic organic synthesis. It is suggested that C/H/O/S ratios are important factors in controlling the degree of prebiotic organic synthesis and, hence, the emergence of life, since if oxygen is abundant, CO2 and SO2 would have been dominant species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006369
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  • 3
    Electronic Resource
    Electronic Resource
    Isodicentric Y chromosome: cytogenetic, molecular and clinical studies and review of the literature (1995)
    Springer
    Human genetics 〈Berlin〉 96 (1995), S. 119-129 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Dicentrics are among the most common structural abnormalities of the human Y chromosome. Predicting the phenotypic consequences of different duplications and deletions of dicentric Y chromosomes is usually complicated by varying degrees of mosaicism (45,X cell lines), which may, in some cases, remain undetected. Molecular studies in patients with dicentric Y chromosomes have been few, and only two studies have attempted to determine the presence of SRY (the putative testis-determining factor gene). We report an 18-year-old female with short stature, amenorrhea, hirsutism, hypoplastic labia minora, and clitoromegaly who has a 45,X/46,X,idic(Y)(p11.32)/47,X,idic(Y)(p11.32),idic(Y) (p11.32) karyotype. Southern analysis using Y-specific probes (Y97, 2D6, 1F5, pY3.4) and polymerase chain reaction (PCR) analysis using primers for ZFY and SRY were positive for all loci tested, indicating that almost all of the Y chromosome was present. Our findings and an extensive review of the literature emphasize the importance of molecular analyses of abnormal Y chromosomes before any general conclusions can be reached concerning the relative effects of the Y-chromosome abnormality and mosaicism on sexual differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214200
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  • 4
    Electronic Resource
    Electronic Resource
    Increased H-2Dd expression following infection by a molecularly cloned ecotropic MuLV (1990)
    Springer
    Immunogenetics 31 (1990), S. 94-103 
    Details
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The biological consequences of radiation leukemia virus (RadLV) infection include the stimulation of H-2Dd antigen expression in resistant mouse strains and thymoma induction in susceptible strains. In an effort to understand the genetic basis of these phenomena, the integrated ecotropic RadLV genome has been examined in a number of primary RadLV-induced tumors, as well as thymomas adapted to in vitro passage; considerable heterogeneity was observed. Examination of these polymorphic viral sequences should help define the viral gene(s) involved in the biological effects of RadLV infection; toward this end, integrated RadLV genomes were molecularly cloned and examined. The genomes and their flanking sequence were characterized by restriction enzyme analysis. Three unique viral genomes were obtained which represent four integration sites. The three RadLV genomes are shown to carry polymorphisms of the original tumor. Following DNA transfection, one of the three genomes replicated in and reinfected both mouse thymocytes and fibroblasts, but not mink fibroblasts in vitro. Virus encoded by the other two DNA genomes could not be recovered following transfection into any of the three cell types. One of these two apparently defective retroviruses encodes a truncated p15E molecule, while the other has elongated long terminal repeats (LTRs). The non-defective ecotropic isolate was collected from in vitro tissue culture supernatants, concentrated, and used to infect mice. Thymocytes of infected, resistant mice were shown to express elevated levels of H-2Dd antigen as early as 12 days post infection, a hallmark of RadLV infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00661219
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  • 5
    Electronic Resource
    Electronic Resource
    Bias correction and forward-backward averaging in frequency/DOA tracking problems (1996)
    Springer
    The journal of VLSI signal processing systems for signal, image, and video technology 14 (1996), S. 93-105 
    Details
    ISSN: 1573-109X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper, we discuss some issues relevant to frequency and direction of arrival (DOA) tracking problems. First, we develop a linear Frequency Modulated (FM) signal model for accurately describing windowed, slowly time varying narrowband signals that typically occur in tracking problems. We then derive first order bias expressions for the peak locations of a Discrete Time Fourier Transform (DTFT) spectrum of a windowed, slowly time varying linear FM signal. We also show that Forward-Backward (FB) averaging is generally inappropriate for nonstationary data, but that it is appropriate when applied to tracking the frequencies of windowed, slowly time varying narrowband signals. A major motivation for using FB averaging is to increase the efficiency of subspace based frequency/DOA estimation in tracking problems. Finally, simulations confirm our first order bias expressions, and show that FB averaging does not significantly alter (or degrade) the time varying MUSIC based frequency estimation performance over that of Forward only averaging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00925271
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of selection and fate of substrates supplied to anaerobic bacteria involved in the corrosion of pipe-line steel (1992)
    Springer
    Journal of industrial microbiology and biotechnology 10 (1992), S. 207-215 
    Details
    ISSN: 1476-5535
    Keywords: Corrosion ; Sulphate=reducing bacteria ; Impedance spectroscopy ; Carbon steel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The corrosion of AISI C1020 carbon steel in an anoxic, marine, sulphide-containing environment was examined as a function of bacterial physiology and consortial complexity. The carbon steel was exposed to three organism;Eubacterium limosum, Desulfovibrio sp. andDesulfobacter sp. which were provided with H2/CO2, butanol, glucose, and acetate as carbon and electron sources. A consortium of these bacteria utilizing hydrogen gave rise to relatively high corrosion rates (5.7×10−4 mhos cm−2) with respect to corrosion resulting from bacteria supplied with organic electron sources (0.6–1.6×10−4 mhos cm−2). Disproportionation of electrons between sulphate reduction and fermentation had a significant effect on the corrosion rate in the case ofDesulfovibrio. Surface examination using scanning electron microscopy coupled with electrochemical impedance spectroscopy supported the hypothesis that the corrosion rate was controlled by the relative intactness of a ferrous sulphide film in which the bacteria were embedded.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569768
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  • 7
    Electronic Resource
    Electronic Resource
    Adolescent idiopathic scoliosis as developmental instability (1995)
    Springer
    Genetica 96 (1995), S. 247-255 
    Details
    ISSN: 1573-6857
    Keywords: scoliosis ; developmental instability ; directional asymmetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adolescent idiopathic scoliosis is the most common spinal deformity affecting children, with a prevalence from mass screening programmes of 1–3%. Despite centuries of study, it remains a problem with no generally accepted theory of aetiology, and disagreement on its natural history and management. Because the deformity consists ultimately of gross left-right asymmetry, a study was undertaken to test the hypothesis that it might be a manifestation of developmental instability. Palmar dermatoglyphics in 112 normal subjects, 62 with non-scoliosis trunk asymmetry and 85 with defined adolescent idiopathic scoliosis were examined and both the absolute right-left difference and the ratio of this to the total were considered. There was increased fluctuating asymmetry of atd difference in those with any asymmetry, scoliotic or not, and increased directional asymmetry of ab and cd ridge counts only in those with pure scoliosis. This suggests that, at adolescence, developmental instability may result in a loss of symmetry in growth, and that in the presence of an increased developmental left-right gradient, this may be of sufficient severity to be classified as deformity and come to the attention of orthopaedic surgeons. This interpretation changes the focus of many previous observations on scoliosis and raises the prospect that developmental stability in humans has relevance to problems hitherto restricted to clinical practice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01439579
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  • 8
    Electronic Resource
    Electronic Resource
    An improved laser-Rayleigh scattering photodetection system (1989)
    Springer
    Experiments in fluids 7 (1989), S. 435-440 
    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 An improved photodetection system for high resolution laser-Rayleigh scattering measurements has been developed that utilizes a solid state detector coupled to a custom-designed, low-noise, transimpedance amplifier. The resulting system, based on a PIN photodiode is less expensive, inherently safer, less delicate and, depending on the detected light level, may exhibit higher signal-to-noise ratios than photodetection systems based on photomultiplier tubes. The frequency response of the system was designed to be uniform (3% peak variation) from DC to nearly 100 kHz. Concentration fluctuation spectra of a high scattering cross-section label (jet fluid) gas discharging into a density-matched, low scattering cross-section quiescent reservoir gas were measured using this system. Spectral signal-to-noise ratios as high as 7 decades were achieved under some conditions in parts of the spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00187060
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  • 9
    Electronic Resource
    Electronic Resource
    In situ force-balance tensiometry (1999)
    Springer
    Experiments in fluids 27 (1999), S. 157-166 
    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  Although a fundamental physical parameter, surface tension is difficult to measure. Common tensiometry inaccuracy comes from failure to control air–liquid–solid contact conditions, or account for liquid meniscus geometry and buoyancy corrections. This paper describes an in situ tensiometry technique, based on withdrawal of a thin-walled tube from the liquid interface, that enforces a known air–liquid–solid contact condition. This technique can be pursued at any level of experimental hygiene. Experimental results for filtered tap water, an alcohol–water solution, and a surfactant–water solution show that results repeatable to three significant digits are obtained with modest effort for a variety of geometrical parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050340
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  • 10
    Electronic Resource
    Electronic Resource
    Combinations of methods for monitoring the microcirculation of the brain (1995)
    Springer
    Neuroscience and behavioral physiology 25 (1995), S. 266-272 
    Details
    ISSN: 1573-899X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02360216
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