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  • Biochemistry and Biotechnology
  • Chemistry
  • General Chemistry
  • Geophysics
  • Humans
  • Inorganic Chemistry
  • Numerical Methods and Modeling
  • Springer  (10)
  • 1995-1999  (10)
  • 1950-1954
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  • 1
    Digitale Medien
    Digitale Medien
    Analysis of otolith chemistry in Nassau grouper (Epinephelus striatus) from the Bahamas and Belize using solution-based ICP-MS (1999)
    Springer
    Coral reefs 18 (1999), S. 171-178 
    Details
    ISSN: 1432-0975
    Schlagwort(e): Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract  We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003380050176
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  • 2
    Digitale Medien
    Digitale Medien
    An Approach to a Visual Language for Convective Fluid Flows: Visualization of Geophysical Simulations (1998)
    Springer
    Visual geosciences 3 (1998), S. 1-19 
    Details
    ISSN: 1610-2924
    Schlagwort(e): Geophysics ; Numerical modelling ; Visualization ; Language ; Convection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract It was known that deep within numbers and binary data from simulations of geophysical convective flows resided various patterns. Two models of convective fluid flows were being considered. One was a model of two-dimensional (768 × 256) air convection with finite Prandtl number of one and Rayleigh number of 108−1010, and another was a model of three-dimensional (up to 120 × 120 × 90) mantle convection with infinite Prandtl number and Rayleigh number of 106−108. Clearly, phenomena existed which superceded each individual dimensionless computer model to provide a piece of information regarding actual fluid flows. The problem was how to find, prove, and communicate these patterns and phenomena for convection simulations with gigabytes of data. In a search for such an analytical and communicative tool, the alternative of visualization was considered. The need for visualization was recognized and discussed. Then, utilizing both two- and three-dimensional models of high Rayleigh number convection, basic techniques of style and content were developed. Applications of the visualization techniques were designed utilizing IBM’s Data Explorer in order to create communicative images and movies, and after the applications, the problems of data storage and transfer became apparent. Throughout the process though, it became clear how important the language of vision actually could be in the geophysics community. In a field in which words such as plumes and internal waves have in ways replaced mathematics as the basic language for science, there is a need for another resource, another language-the visualization of convective fluid flows.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s10069-998-0001-3
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  • 3
    Digitale Medien
    Digitale Medien
    Perception of shape from shading in chimpanzees (Pan troglodytes) and humans (Homo sapiens) (1998)
    Springer
    Animal cognition 1 (1998), S. 25-35 
    Details
    ISSN: 1435-9456
    Schlagwort(e): Key words Shape from shading ; Visual search ; Texture segregation ; Chimpanzees ; Humans
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The perception of shape from shading was tested in two chimpanzees (Pan troglodytes) and five humans (Homo sapiens), using visual search tasks. Subjects were required to select and touch an odd item (target) from among uniform distractors. Humans found the target faster when shading was vertical than when it was horizontal, consistent with results of previous research. Both chimpanzees showed the opposite pattern: they found the target faster when shading was horizontal. The same difference in response was found in texture segregation tasks. This difference between the species could not be explained by head rotation or head shift parallel to the surface of the monitor. Furthermore, when the shaded shape was changed from a circle to a square, or the shading type was changed from gradual to stepwise, the difference in performance between vertical and horizontal shading disappeared in chimpanzees, but persisted in humans. These results suggest that chimpanzees process shading information in a different way from humans.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100710050004
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  • 4
    Digitale Medien
    Digitale Medien
    Turbulent mixing of reactive gases in the convective boundary layer (1997)
    Springer
    Boundary layer meteorology 85 (1997), S. 197-222 
    Details
    ISSN: 1573-1472
    Schlagwort(e): Turbulence ; Chemistry ; Closure ; Convective boundary layer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract We study the interactions of chemistry and turbulent mixing of tracersin the convective boundary layer with a second-order closure model,including higher order chemistry terms. In order to limit the number of predictive equations we prescribe the profiles for ¯w¯Θ, ¯w¯θ ¯θ and the lengthscale l. However, for model validation we treat temperature and humidity asinert tracers, and compare the results with profiles observed during theAir Mass Transformation Experiment, and with similarity expressions for thesurface layer. We find good agreement of the mean profiles, but the (co-)variances are slightly underpredicted. Furthermore, the model usesdiagnostic equations expressing third moments of concentration in terms ofsecond moments and their vertical derivatives. They are compared withlarge-eddy model results, showing good agreement and, therefore, thesimplifications are justified. The model is applied to the transport of two gases subject to one bimolecular reaction. The importance of concentration correlations on themean transformation rate is studied. For two gases diffusing in oppositedirections we find for moderate and fast chemistry a 50% and90% decreased transformation rate due to the negatively correlatedconcentrations. These values are similar to large-eddy results of Schumannand Sykes et al. For two bottom-up tracers we find that the covariance ofboth reactive species is either positive or negative, increasing or reducingthe effective transformation rate depending on the Damköhler number (the ratio of the turbulent and the chemistry timescale). A significantdirect influence of chemistry on the flux divergence is found in bothcases. According to the model the effective transport to mid-levels of theboundary layer is increased when two reactive tracers diffuse in oppositedirections, and decreased in the case of two bottom-up tracers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1000414710372
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  • 5
    Digitale Medien
    Digitale Medien
    Perceptions of chemistry: Why is the common perception of chemistry, the most visual of sciences, so distorted? (1996)
    Springer
    Journal of science education and technology 5 (1996), S. 193-201 
    Details
    ISSN: 1573-1839
    Schlagwort(e): Chemistry ; chemistry education ; multiple intelligences ; imagery ; visual-spatial thinking
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Allgemeine Naturwissenschaft , Technik allgemein
    Notizen: Abstract Chemistry has evolved from a science dominated by mathematics into a science highly dependent on spatial-visual intelligence. Yet the chemical content of introductory courses remains taught essentially the same as 40–50 years ago. Chemistry, today, is recognized by chemists as the molecular science. Yet, school chemistry is alienated from that perception. Thanks to the computer, young people are more comfortable with visual imaging than their instructors were at the same age. Thus the time is rife to reinvigorate chemistry education by means of the visual-spatial approach, an approach wholly in conformance with the way modern chemistry is thought about and practiced.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575303
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  • 6
    Digitale Medien
    Digitale Medien
    The importance of radioactivity in geoscience and mining (1995)
    Springer
    Cellular and molecular life sciences 51 (1995), S. 703-709 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Geophysics ; geology ; natural radioactivity ; radiometry ; mining ; uranium ores ; radon ; disposal of radioactive waste
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Almost simultaneously with Roentgen rays, natural radioactivity was discovered. Its investigation led to important fundamentals of the geosciences: petrophysics, terrestrial heat flow, isotope geology, and absolute geological chronology. In applied geophysics and geology, exploration of radioactive ores and of tectonic faults, and radiometric well loggings, are used. Production of radioactive water and mining for uranium ores are discussed, including their development (especially in the Saxon ore mountains) and the consequences on health (radon in underground air and houses). Disposal of radioactive waste is touched on briefly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01941267
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  • 7
    Digitale Medien
    Digitale Medien
    Observations of chemical processing in the circumstellar environment (1995)
    Springer
    Astrophysics and space science 224 (1995), S. 81-84 
    Details
    ISSN: 1572-946X
    Schlagwort(e): Chemistry ; Depletions ; Shocks ; IRAS 05338-0624 ; NGC 1333 IRAS 4
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract High resolution interferometer and single-dish observations of young, deeply embedded stellar systems reveal a complex chemistry in the circumstellar environments of low to intermediate mass stars. Depletions of gas-phase molecules, grain mantle evaporation, and shock interactions actively drive chemical processes in different regions around young stars. We present results for two systems, IRAS 05338-0624 and NGC 1333 IRAS 4, to illustrate the behavior found and to examine the physical processes at work.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00667826
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  • 8
    Digitale Medien
    Digitale Medien
    The role of the Hermanus Magnetic Observatory in geomagnetic field research (1995)
    Springer
    Astrophysics and space science 230 (1995), S. 439-456 
    Details
    ISSN: 1572-946X
    Schlagwort(e): Geophysics ; geomagnetic field
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Geomagnetic field research carried out at the Hermanus Magnetic Observatory over the past decade is reviewed. An important aspect of this research has been the study of geomagnetic field variations, with particular emphasis on ULF geomagnetic pulsations. Features of geomagnetic pulsations which are unique to low latitude locations have been investigated, such as the cavity mode nature of low latitude Pi 2 pulsations and the role played by ionosphericO + ions in the field line resonances responsible for Pc 3 pulsations. A theoretical model has been developed which is able to account for the observed relationships between geomagnetic pulsations and oscillations in the frequency of HF radio waves traversing ionospheric paths. Other facets of the research have been geomagnetic field modelling, aimed at improving the accuracy and resolution of regional geomagnetic field models, and the development of improved geomagnetic activity indices.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00658201
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  • 9
    Digitale Medien
    Digitale Medien
    The importance of chemical data for the study of interstellar shocks (1995)
    Springer
    Astrophysics and space science 233 (1995), S. 125-137 
    Details
    ISSN: 1572-946X
    Schlagwort(e): Interstellar Medium ; Dark Clouds ; Chemistry ; Bistability ; C-shock Waves
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Shock waves perturb the chemical state of the interstellar gas. We consider the effects of C-shocks on the composition of molecular clouds, for a range of values of the pre-shock gas density and magnetic induction. The time required to re-establish equilibrium in the post-shock gas depends on the initial conditions and can become very large. The significance of the two known chemical phases of dark clouds and of bistability is considered in this context.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00627340
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  • 10
    Digitale Medien
    Digitale Medien
    Molecular diagnostics of diffusive boundary layers (1995)
    Springer
    Astrophysics and space science 233 (1995), S. 161-164 
    Details
    ISSN: 1572-946X
    Schlagwort(e): Stars ; Chemistry ; Diffusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We have assessed the role of diffusion in determining chemical abundances in molecular interface regions. Chemical models have been developed which include the appropriate diffusion terms and that are appropriate to a narrow diffusion region (∼0.01pc) that may exist at the interface between a dark core and a hot, shocked T-Tauri wind. We have assumed pressure balance throughout and have calculated the chemical abundances as functions of time and position through the interface. The results show that significant enhancements of detectable molecules/transitions are expected (e.g. CO J=6→5, OH and CH). Using a realistic value of the diffusion coefficient a diffusive region of dimension 0.01pc may be established within about 104 years. In general it seems likely that diffusion processes are highly significant on these and smaller lengthscales.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00627344
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