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  • 1
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 54 (1999), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In Lake Baikal, three morphotypes of omul Coregonus autumnalis migratorius are recognized; the littoral, pelagic, and deep-water forms. Morphotype assignment is difficult, and similar to that encountered in pelagic and deep-water coregonines in the Laurentian Great Lakes. Principal component analysis revealed separation of all three morphotypes based on caudal peduncle length and depth, length and depth of the body between the dorsal and anal fin, and distance between the pectoral and the pelvic fins. Strong negative loadings were associated with head measurements. Omul of the same morphotype captured at different locations were classified to location of capture using step-wise discriminant function analysis. Jackknife correct classifications ranged from 43 to 78% for littoral omul from five locations, and 45–86% for pelagic omul from four locations. Patterns of location misclassification of littoral omul suggested that the sub-population structure, hence stock affinity, may be influenced by movements and intermixing of individuals among areas that are joined bathymetrically. Pelagic omul were more distinguishable by site and may support a previous hypothesis of a spawning-based rather than a foraging-based sub-population structure. Omul morphotypes may reflect adaptations to both ecological and local environmental conditions, and may have a genetic basis.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    HNO 46 (1998), S. 815-820 
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Knalltrauma ; Spielzeug ; Knallpistolen ; Normung ; Knallmessung ; Key words Acute acoustic trauma ; Toy pistols ; Loudness standards ; Impulse noise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary In order to understand the repeated occurrences of auditory impairments caused by toy pistols, an analysis of the circumstances involved was performed at Justus-Liebig University of Giessen. The accoustic impact of toy pistols on the ear was determined with a special measuring system for impulse noise. Results were compared with the acoustic impacts of the G3 common rifle of the German military on the ear of the soldier. It was apparent that all of the five randomly selected types of toy pistols were much louder than the military rifle, if fired close to the ear. The current standard of the European Union related to the safety of toys (EN 71-1) tolerates peaks of impulse noise from toy pistols that are actually illegal for workplaces without auditory protection. Measurements showed that the toy pistols tested were even louder than that tolerated by the EU standard. Problems related to acute acoustic trauma caused by these toys are discussed using recent examples. In order to prevent such injuries, we suggest limiting the loudness of the ”worst case” instead of using unrealistic measurements.
    Notes: Zusammenfassung Das Gefahrenpotential von Kinderpistolen für das kindliche Gehör wurde näher untersucht, nachdem mehrfach bleibende Hörschäden beobachtet wurden. Mittels eines Kunstkopfmeßsystems wurden die Schallpegel gemessen, die Knallpistolen am Ohr des Betroffenen erzeugen können. Zum Vergleich wurden die Spitzenpegel gemessen, die beim Schießen mit dem Gewehr der Bundeswehr (G3) auf das Ohr des Schützen einwirken. Es zeigte sich, daß alle gemessenen Spielzeugpistolen (Revolver), wenn sie in Ohrnähe abgefeuert werden, wesentlich lauter waren als der Knall des G3 für das Ohr des Soldaten. Sie waren ebenfalls lauter als es die für Kinderpistolen geltende EU-Norm (EN 71-1) zuläßt. Diese erlaubt Spitzenpegel, die an Lärmarbeitsplätzen der EU ohne Gehörschutz verboten sind. Die Problematik des durch solche Pistolen hervorgerufenen Knalltraumas wird anhand aktueller Beispiele diskutiert. Zur Vermeidung von Hörschäden durch Kinderspielzeug wird gefordert, daß bei der Normung keine realitätsfernen Meßverfahren Anwendung finden. Statt dessen sollte der schlimmst mögliche Fall (worst case) bei der Messung und Bewertung zugrunde gelegt werden.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    HNO 47 (1999), S. 535-540 
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Hörschäden ; Knalltrauma ; Kinder ; Tinnitus ; Erweiterte Hochtonaudiometrie ; Key words Hearing loss ; Acoustic trauma ; Children ; Tinnitus ; High-frequency audiometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The study presents an analysis of 20 cases of acute acoustic trauma caused by toy pistols. The problem generally involves boys within the age range from 6 to 11 years. Half of the incidents involved attacks with toy pistols used as weapons. Auditory damage appeared in two types, each of which had a notch in the audiogram at the frequency range between 10 and 14 kHz. In children, a shot close to one ear can damage both ears. Great differences in the severity of tinnitus were apparent. The most severe cases of tinnitus were observed in the children with no or minor premanent auditory damage. Children experiencing long periods of uninterrupted tinnitus suffer significantly. This is not only detrimental to family-life but also to the performance of the children at school. The total expenses of treatment for these 20 cases were estimated to be approximately 80,000 DM (40.000 Euro).
    Notes: Zusammenfassung Im Rahmen einer Studie wurden 20 Fälle von Knalltraumata durch Kinderpistolen erfaßt und ausgewertet. Die Problematik betrifft fast nur männliche Personen und schwerpunktmäßig den Altersbereich von 6–11 Jahren. Die Hälfte der Vorfälle waren Angriffe, bei denen die Kinderpistole als Waffe eingesetzt wurde, 2 Typen von Hörschäden sind festzustellen, die jedoch beide durch eine Senke im Bereich von 10–14 kHz charakterisiert sind. Bei Kindern kann der Schuß in eines der Ohren auch das andere Ohr schädigen. Sehr große Unterschiede bestehen im Auftreten von Tinnitus. Die Fälle mit starkem Tinnitus haben keine oder nur geringe bleibende Hörschäden. Die von Knalltraumata betroffenen Kinder leiden oft sehr stark unter langanhaltendem Tinnitus. Dabei wird nicht nur das Leben der Familien beeinträchtigt, sondern auch die schulischen Leistungen der Kinder leiden teilweise sehr stark darunter. Für die Therapie dieser 20 Fälle entstanden Gesamtkosten von ca. 80.000,- DM
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-1536
    Keywords: Key words Poly(propylene)glycole ; transient entanglements ; field gradient NMR ; self-diffusion ; dielectric relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  We report measurements of the temperature dependence of the self-diffusion of a poly(propylene glycole) in the melt. Two kinds of magnetic field gradient NMR are used: pulsed field gradient NMR with large field gradients and static field gradient NMR in a specially designed cryomagnet. The emphasis is put on large field gradients. The (true) long-time self-diffusion coefficients are compared with those calculated from normal-mode relaxation times in dielectric spectroscopy using the Rouse model. They agree very well. For temperature below about 270 K, a time-dependent self-diffusion coefficient appears which is an indication of anomalous diffusion. At 253 K we observe complete transient entanglement behaviour of the PPG melt. These results are discussed in comparison with dielectric and other experimental data.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-1536
    Keywords: Key words Copolymers ; restricted self-diffusion ; interfaces ; pulsed field gradient NMR ; static light scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The self-diffusion behavior of a triblock copolymer (PEO–b– PPO–b–PEO) in an aqueous solution of 20% (m/m) was investigated during a temperature-induced phase transition from liquid to gel state using pulsed field gradient NMR and static light scattering. The measured self-diffusivity shows a strong dependence on the observation time in the gel phase indicating the existence of diffusion barriers in the size range of about 0.6 μm. Additional static light-scattering measurements show a structure in the same size range of several hundred nanometers, which is far above molecular or micellar sizes and thus, has to be caused by larger clusters. The similarity in the space scales suggests that the restriction of molecular propagation is correlated with the grain boundaries between the domains of the poly-crystalline structure formed by the arranged micelles.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 274 (1996), S. 89-91 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 275 (1997), S. 807-813 
    ISSN: 1435-1536
    Keywords: Key words Polymer melt ; asymmetric diblock copolymer ; polyisoprene-b-polystyrene ; disorder-to-order transition ; micelles ; chain self-diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The self-diffusion in a polystyrene-b-polyisoprene diblock copolymer with a strongly asymmetric composition was investigated with dependence on temperature by pulsed field gradient (PFG) NMR. The diblock shows with decreasing temperature a disorder-to-order-transition at T ODT=393 K from a micellar liquid-like to a bcc ordered state which was recently measured by SAXS [M. Schwab and B. Stühn, Phys. Rev. Lett. (1996) 76: 924]. Two diffusivities were observed, one of the free diblock chains and one of the diblock chains fixed in micelles. The volume fraction of free chains decreases with decreasing temperature. The diffusivity of the free chains must be related to chain stretching. The experiments show that within the time of the NMR experiment (300 ms) there is no exchange between the diblock chains in the free state and those fixed in the core of the micelles.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1435-1536
    Keywords: Key words Diblock copolymers ; Micelles ; Solutions ; Self-diffusion ; Pulsed field gradient nuclear magnetic resonance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The self-diffusion of a polystyrene-b-poly(ethylene-co-propylene) diblock copolymer dissolved in a preferential solvent for the aliphatic block, n-decane, was investigated by pulsed field gradient NMR. The diblock copolymer forms micelles in solution, the structure of the solid polymer being preserved in the native solution because the polystyrene is in the glassy state. The equilibrium state is attained upon heating which again freezes in upon cooling to room temperature. The hydrodynamic radius of the micelles decreases by about 50% during this heating–cooling process. The concentration dependence of the self-diffusivity shows typical colloidlike behaviour, and it can be described by a Vogel–Fulcher–Tammann-like equation. No indications of crystallization at higher concentrations are observed in the micellar solution because the micellar sizes are slightly polydisperse. The self-diffusivity was measured up to the glasslike state, where in-cage- diffusion and dynamic heterogeneities could be detected.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The composition, f, and concentration, φ, dependence of the self-diffusion coefficients of diblock copolymers in solutions in a common good solvent have been investigated by pulsed-field-gradient nuclear magnetic resonance and photon correlation spectroscopy. The difference in the entanglement characteristics of the parent homopolymers was found to be very important in determining the diffusion coefficients. The investigation on toluene solutions for a series of poly(styrene-b-isoprene) diblocks, possessing almost similar molecular weights and compositions ranging from 0.18 to 0.74, showed that the dependence of the diffusivity on diblock composition f conforms with the progressive transition from the Rouse to the entanglement regime at different concentrations due to the different critical molecular weights for entanglement of the parent homopolymers. The same idea can account for the diblock composition dependence of the self-diffusivity for poly(styrene-b-butadiene) diblocks. Moreover, the self-diffusivities for three poly(styrene-b-methyl methacrylate) diblocks in toluene are insensitive to copolymer composition (0.35 to 0.69) in accord with the very similar entanglement characteristics of the two blocks.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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