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  • 1
    ISSN: 1573-9120
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The radiation-driven plasma-turbulence problem is in essence an application problem of electrodynamics. In electrodynamics, electromagnetic fields at any point are determined by all charges and currents in the underlying physical system, the fields' history and physical constraints. Starting from this standpoint, we have proved that radiation-driven electromagnetic turbulence in a plasma can be studied in the same way we study the electrostatic turbulence excited by electromagnetic waves in a plasma by means of a two-fluid approximation, a two-timescale technique, and a two-spacescale technique. The main difference between electromagnetic turbulence model equations and the Zakharov equations governing electrostatic turbulence is that a driving term appears in the former. The physical origin of this driving term is the current that emits the radiation which supplies the free energy source that gives rise to both electromagnetic and electrostatic turbulences. Simulated electromagnetic emissions, large scale density perturbation and anomalous absorption can be calculated quantitatively based on the electromagnetic turbulence model equations.
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  • 2
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Aldehydes, aliphatic ; 1,3-Cyclohexanedione (CHD) ; Fluorimetric detection ; Plasma analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and sensitive method is proposed for the measurement of aldehydes in plasma. The plasma samples are treated with 1,3-cyclohexanedione (CHD) and after addition of the internal standard (the CHD derivative of octaldehyde) are analysed by reversed-phase high-performance liquid chromatography with an acetonitrile-water gradient as the mobile phase. Detection is by fluorimetry with excitation at 395 nm and emission at 457 nm. In plasma samples spiked with aldehydes, the calibration curves showed good linearity in the range 0–10 μg mL−1. The recoveries of aldehydes were quantitative; coefficients of within-day and between-day variation were less than 13% and 11%, respectively. Applications to human and some animal plasma samples are reported.
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  • 3
    ISSN: 1612-1112
    Keywords: Thin-layer chromatography ; Secondary ion mass spectrometry ; Nicergoline ; Semisynthetic alkaloid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A direct combination of thin-layer chromatography with secondary ion mass spectrometry (TLC/SIMS) provides a method for the quantitative analysis of thermally unstable compounds or compounds of low volatility such as nicergoline. The method is very simple and has excellent precision. The analysis was performed by using an aluminium TLC plate and a mixture of methylene chloride, acetone, and distilled water as a developing solvent. After development the portion of the plate with the nicergoline and the internal standard spots was cut off the TLC plate, and was attached to the SIMS holder directly. The amount of nicergoline was determined from the ratio of the fragment ion intensity of the nicergoline to the internal standard. The calibration curve was linear, and the detection limit was 10 ng at a signal-to-noise ratio of 5. This method should be considered for application to the determination of drugs in biological samples and also for the determination of possible impurities and decomposition products in drugs.
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  • 4
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Atmospheric pressure chemical ionization-mass spectrometry ; Dried yeast ; Thiamine ; Ion-pair extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography (HPLC) and high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (HPLC/APCI-MS) have been applied to the analysis of thiamine in dried yeast. Thiamine was extracted from dried yeast with isobutanol containing sodium 1-octanesulfonate as an ion-pairing agent and determined by HPLC on a reversed phase ODS column with UV detection at 254 nm. Response was linear in the range 25–300 μg/g of thiamine in dried yeast with a coefficient of variation in the reproducibility of 8.0%. Thiamine was recovered in good yield (109.2%, n=5). Identification of the thiamine peak was obtained by the mass spectrum using the HPLC/APCI-MS system. The utility of the selected ion monitoring technique using the HPLC/APCI-MS was also investigated. The results obtained by this method are in good agreement with those obtained by the thiochrome method [1].
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  • 5
    ISSN: 1614-7456
    Keywords: Hippocampal neural network ; Hebbian learning ; Phase coding ; Self-orientation ; Home-navigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We propose an artificial neural network model for autonomous agents, i.e., mobile robots, to learn maps of environments and acquire the ability to perform home-navigation autonomously. The networks consists of two subnetworks, each of which has a similar structure with hippocampal lamellar neuronal circuits. Hebbian learning procedures self-organize the first subnetwork to output the distributed sinusoidal activity of the cells by accumulating motor information generated during movement, and the second subnetwork to output localized activity by prototyping sensory information. These patterns represent a homing vector providing the relative coordinates of the agent from a starting point, and a place code corresponding uniquely to a point of the environment. By attaching homing vectors to the sensor map, the homing vector is associated with the sensory stimuli. Then the agents can perform home-navigation autonomously by this association.
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  • 6
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 7
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Solution condition of the lithium electrolyte of LiCF3SO3 salt dissolved in propylene carbonate (PC), dimethoxyethane (DME) and tetrahydrofuran (THF) were investigated based on the measurements of the self-diffusion coefficients of lithium (DLi) and anion (DF) species using the pulsed-field gradient (PFG) NMR, viscosity and conductivity. DLi and DF decreased with the increase in the solution concentration for these electrolytes. This result reflects the change in the dissociation degree of the salt and the viscosity depending on the solution concentration. In the case of PC solution (the dielectric constant (∈) of PC: ∼65), measured DLi and DF were separated each other with the decrease in the concentration because the dissociation of the salt was promoted to increase the content of dissociated ions. With an increase in the concentration, the dissociation would be restricted and DLi and DF approximated each other, which means that the associated ion pairs are dominant in the solution. The effective ionic radius (reff) of cation species of PC solution estimated from the Stokes-Einstein relation using the diffusion coefficient and the viscosity results was four times greater than that of the naked lithium ion and independent of the dissociation degree. On the other hand, the reff of anion species changed depending on the dissociation degree. This suggests that the dissociated lithium ions are solvated by the PC solvent in the solution. DME and THF solutions did not show the solvation effect from the result of the change in reff with the concentration. This suggests that the dissociation degree of the dissolved salt was low due to the low ∈ of their solvents (∈ ∼ 7.2) and the ion pairs would dominant in the solutions independent of the solution concentration.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 210 (1993), S. 245-257 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract AGN (Active Galactic Nuclei) have their profound time variability over a wide range of time scales. Although many results of AGN variability have been provided from wide band wavelength observations, I would like to concentrate the recent problems concerning a nearby region of their central engine based on the X-ray observations which are most efficient to investigate this region. In this paper we will investigate mainly the result of Seyfert galaxies which would be generalized to other AGN.
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  • 9
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the record of the balloon observation which was performed on 27 September, 1970, a transient burst of X-rays was found. This event is concluded to be a cosmic gamma-ray burst of a smaller size or of a larger distance compared to the Vela bursts observed over the X-ray energy range. The energy spectrum is consistent with that of some of the Vela bursts. The time profile of the event is qualitatively similar to the 27 April, 1972 event studied by Apollo 16. The detection of small bursts over the X-ray energy range by the balloon observation during a period of the order of 10 to 100 h is not surprising considering a probable frequency-size distribution of the burst.
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  • 10
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Results of rocket observations of SCO X-1 over the spectral range of 2∼20 keV are presented. The observations have been performed partly in India and partly in Japan under the collaboration of the three groups. The present results are compared with results of similar observations carried out by the LRL (Lawrence Radiation Laboratory) group. Some of these X-ray observations were accompanied by simultaneous optical observations. Relationships between the hardness of the X-ray spectrum and the X-ray intensity and between the hardness and the optical luminosity are compiled. The relationships among the parameters (temperature, density and size) which characterize the postulated isothermal cloud model of SCO X-1 are given. They indicate that SCO X-1 is characterized by a temperature of about 107–108K, a density of about 1016–1017 cm−3 and a radius of about 108–109 cm respectively. We further show that the temperature is inversely correlated with the size of the source; an increase in temperature corresponds to a decrease in the radius and an increase in density.
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