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  • 1
    Digitale Medien
    Digitale Medien
    Loss calculations in bent multimode optical waveguides (1979)
    Springer
    Optical and quantum electronics 11 (1979), S. 173-183 
    Details
    ISSN: 1572-817X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract We present a straightforward geometric optics method to calculate the power attenuation induced by a circular bend in the axis of a multimode optical waveguide. The method involves tracing of rays and use of generalized power transmission coefficients. Both slab and fibre waveguides (with either step-index or parabolic core profiles) have been considered; the source has been assumed to be Lambertian.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00624396
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  • 2
    Digitale Medien
    Digitale Medien
    Comptel analysis of GRB 940217 (1995)
    Springer
    Astrophysics and space science 231 (1995), S. 153-156 
    Details
    ISSN: 1572-946X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract COMPTEL on board CGRO has observed a very strong (S[〉 0.3 MeV] = 2.03 × 10−4 erg cm−2), complex, and long lasting (162 s) gamma-ray burst on February 17, 1994 (GRB 940217). Temporal fluctuations occur on timescales as short as 100 ms. Hard-to-soft spectral evolution has been observed during the burst emission and also within individual peaks. The photon spectra obtained within the 6 peaks can be modelled by single power law spectra and by broken power laws with break energies at around 1 MeV. The best-fit power law slopes vary between 1.1 and 3.5 throughout the event. The burst is located at [α 2000,δ 2000] = [29.5°, 3.8°] with a 3σ error radius of 0.9°. COMPTEL does not detect any significant “post-burst” emission (as reported by EGRET) at low energies (〈 30 MeV), and our upper limits are marginally consistent with the EGRET detections. Using high energy spectral and temporal information, distance limits to GRB 940217 have been derived.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00658606
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  • 3
    Digitale Medien
    Digitale Medien
    Analysis of COMPTEL gamma-ray burst locations and spectra (1995)
    Springer
    Astrophysics and space science 231 (1995), S. 231-234 
    Details
    ISSN: 1572-946X
    Schlagwort(e): gamma-ray bursts: observations ; locations ; spectra
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract In its first three years of operation, the COMPTEL instrument on theCompton Gamma-Ray Observatory has measured the locations (mean accuracy ∼1°) and spectra (0.75-30 MeV) of 18 gamma-ray bursts and continues to observe new events at a rate of ∼1/month. With good angular resolution and sensitivity at MeV energies, the growing COMPTEL burst catalog is an important new piece of evidence in the on-going GRB mystery. The COMPTEL burst locations are consistent with an isotropic distribution of sources, yet the spatial coincidence of two of the bursts indicates the possibility of repetition. The COMPTEL burst spectra are in most cases consistent with a single power law model with spectral index in the range 2–3. However, two bursts show evidence of a spectral break in the MeV range. Measurement of rapid variability at MeV energies in the stronger bursts provides evidence that either the sources are nearby (within the Galaxy) or the gamma-ray emission is relativistically beamed. We present an overview of analysis results obtained from the COMPTEL burst catalog concentrating on the search for burst repetition and the implications of highly variable MeV emission.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00658622
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  • 4
    Digitale Medien
    Digitale Medien
    Untersuchungen über das Verhalten einer Reihe von Elementen gegenüber Brenzcatechin in wäßriger Lösung (1965)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 210 (1965), S. 27-34 
    Details
    ISSN: 1618-2650
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Pyrocatechol has been added to solutions of many elements at pH 5,0 (concentrations up to 200 mg/250 ml) under the conditions used for the potentiometric titration of germanium. It was observed that many elements react with pyrocatechol to give hydrogen ions, among others all elements Investigated which forminsoluble hydroxides or oxide hydrates at pH 5. Only the reactions of germanium and lead can be used for volumetric analysis (titration with sodium hydroxide) because of their accurate reproducibility. Germanium is separated from interfering elements by suitable methods. For lead an immediate titration is possible but many elements interfere and their concentrations should be very small except in the case of thallium, zinc and cadmium. Buffering substances must be absent. On the other hand, pyrocatechol can be determined in the presence of other organic compounds especially resorcinol and hydroquinone by a neutralized solution of lead and titration with sodium hydroxide. It is assumed that the other compounds do not react with lead and give no buffering effect.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00515693
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  • 5
    Digitale Medien
    Digitale Medien
    Untersuchung von Fleisch, Fisch und Fleischbrüherzeugnissen (1941)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 121 (1941), S. 269-271 
    Details
    ISSN: 1618-2650
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01388042
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  • 6
    Digitale Medien
    Digitale Medien
    Spectral characterisation of gamma-ray bursts with COMPTEL and BATSE (1995)
    Springer
    Astrophysics and space science 231 (1995), S. 157-160 
    Details
    ISSN: 1572-946X
    Schlagwort(e): Gamma-ray bursts ; spectra
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Although the earliest observed gamma-ray burst spectra were well described by thermal bremsstrahlung models, subsequent observations above 1 MeV showed the existence of high energy power law tails in ∼60% of events. In order to accurately characterise burst spectra, both the low energy turnover and the high energy tail must be accounted for. We have addressed this issue by jointly deconvolving spectra obtained by BATSE and COMPTEL onboard theCompton Observatory. We present preliminary results obtained by application of this method to the gamma-ray burst of February 17, 1994.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00658607
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  • 7
    Digitale Medien
    Digitale Medien
    Mission aspects of GRASP ESA's prospective gamma-ray astronomy satellite (1989)
    Springer
    Space science reviews 49 (1989), S. 173-177 
    Details
    ISSN: 1572-9672
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Mission aspects of the project GRASP (Gamma-Ray Astronomy with Spectroscopy and Positioning) are described as documented in the ESA assessment study at the end of 1986. The goals of this study addressed scientific objectives, technical solutions and feasibility of the mission. Two accommodation studies accompanied the assessment study. Their results show that GRASP can be accommodated on two existing space platforms, EURECA-B and ROBUS, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173752
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  • 8
    Digitale Medien
    Digitale Medien
    The GRASP telescope (1989)
    Springer
    Space science reviews 49 (1989), S. 157-171 
    Details
    ISSN: 1572-9672
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The GRASP mission Gamma-Ray Astronomy with Spectroscopy and Positioning addresses the scientific goals of fine spectroscopy with imaging and accurate positioning of gamma-ray sources, an unexplored area within gamma-ray astronomy. The assessment of GRASP as a future space astronomy mission in the mid-1990s has led to the design of the instrument outlined in this article. Thus GRASP is a third generation gamma-ray telescope and is designed to operate as a high quality spectral imager in the mid-1990s, when, following the GRO, SIGMA, and GAMMA-1 missions, there will be requirement for a more sophisticated instrument to maintain the momentum of advance in gamma-ray astronomy. The telescope will be capable of locating point sources with a precision of typically 1 arc min, whilst making a fine spectral analysis (E/ΔE ∼ 1000) of any gamma-ray line features. The high sensitivity of this instrument and the long (〉 2 year) lifetime of the mission will enable a large number (∼ 1000) of astronomical objects to be studied. The GRASP mission has the potential to move gamma-ray astronomy from an era of basic exploration to one in which detailed and novel measurements can be used to gain a better understanding of many astrophysical problems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173751
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  • 9
    Digitale Medien
    Digitale Medien
    Production and stability of oxygen cluster cations and anions, revisited (1991)
    Springer
    The European physical journal 20 (1991), S. 201-203 
    Details
    ISSN: 1434-6079
    Schlagwort(e): 36.40
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Stoichiometric and non-stoichiometric, positive and negative oxygen cluster ions (n up to 70) have been produced in a crossed neutral beam/electron beam ion source. The abundance and stability of the ions formed have been analyzed with a double focussing sector field mass spectrometer in a series of experiments. Positive and negative ion mass spectra observed exhibit distinct abundance anomalies, however, at different cluster sizes. Abundance maxima and minima correlate with correspondingly small and large metastable fractions of (O2) n + and (O2) n − ions, respectively. (O2) n + ions may also lose up top=(n−1) monomers by collision induced dissociation with monotonously decreasing probability with increasingp. Metastable fractions determined for (O2) n − ions produced with appr. zero eV electrons are in general larger than those for ions produced with appr. 7 eV electrons. (O2) n − ions are also observed to decay via autodetachment, with lifetimes increasing with increasing cluster size. Finally, here we were able to prove that an apparent loss of the monomer fragment O (and higher homologues) observed in the metastable time regime is due to ordinary metastable monomer evaporation in the acceleration region. Moreover, we will also present here some new data and interpretation concerning the electron attachment cross section function for O2 clusters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543973
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  • 10
    Digitale Medien
    Digitale Medien
    Comparative evaluation of labelling patterns and turnover of lipids, tagged by 15 /p-123I-phenyl-/ pentadecanoic and 1-14C-palmitic acid (1984)
    Springer
    Journal of radioanalytical and nuclear chemistry 86 (1984), S. 231-245 
    Details
    ISSN: 1588-2780
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Energietechnik
    Notizen: Abstract Uptake and turnover of chloroform/methanol extractable tissue lipids labelled in vivo simultaneously with 15/p-123I-phenyl-/pentadecanoic and l-14C-palmitic acid were compared. Lipid turnover studies were performed in fasted pentobarbital-anaesthetized Wistar rats in tissues with highly varying free fatty acid turnover rates. In all tissues investigated, i.e. heart, lung, liver, spleen and kidneys, both tracers labelled nearly identical lipid fraction. Main tracer uptake was found in free fatty acids, phospholipids, diglycerides and triglycerides. A highly significant correlation of uptake and turnover in main tissue lipid fraction indicated an essentially identical metabolic pathway of both tracers in intermediary tissue lipid metabolism. Concordant tracer uptake and turnover patterns in tissue of lipids with highly varying free fatty acid metabolic rates suggested that intrinsic metabolic activity of the tissue and respective lipid fraction was the major determinant of metabolic handling of both iodophenyl fatty- and palmitic acid. Thus, the feasibility of iodophenylpentadecanoic acid as free fatty acid tracer for studying tissue lipid metabolism is demonstrated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02166719
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