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  • 1
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3432-3434 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report on pulse laser oscillation from a p-Ge intervalence band (IVB) laser composed of a Ga-doped Ge crystal measuring about 1×1×5 mm3 which is a very small volume compared with those reported so far for shallow-acceptor-doped Ge. Laser oscillation is only achieved under uniaxial stresses greater than 1300 kg/cm2. We find that the optimum stress for lasing is around 3500–4100 kg/cm2 when the p-Ge IVB lasers are operated at liquid helium temperature. The minimum electric power needed for lasing is only 280 W at a peak period of pulse emission. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 1052-1058 
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The stabilization of low-frequency density fluctuations is evidenced in the Nagoya Bumpy Torus (NBT-1M) [Plasma Physics and Controlled Nuclear Fusion Research (IAEA, Vienna, 1985), Vol. 2, p. 551] in the presence of microwave-heated hot-electron rings. Flute-type fluctuations, which are considered to be stabilized by the charge-uncovering effect of the rings, are found to cause large plasma losses, and to affect radial density profiles in the way that the lower fluctuation level yields the steeper density gradient. The particle confinement is, therefore, improved by the hot-electron rings to some extent, but is mainly determined by the plasma convection, which is expected from the discrepancy between density and potential profiles. It is also found that fluctuations in a toroidal plasma inside the ring grow when a weak negative ambipolar potential and a steep density gradient are formed, and are reduced to a low level when a deep potential well is achieved.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 9354-9360 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The photodissociation of p-methoxytoluene and p-methoxybenzyl alcohol at 266 nm in n-heptane solution is studied by nanosecond fluorescence and absorption spectroscopy. The formation of a p-methoxybenzyl radical is identified by its fluorescence which is induced by excitation at 308 nm. The yields of the radical are of the order of ∼10−3 for dissociation of p-methoxytoluene and p-methoxybenzyl alcohol. The growth rate of 1.5×108 s−1 for the radical is equal to the decay rate of (1.5±0.3)×108 s−1 for the precursor fluorescence in dissociation of p-methoxytoluene, whereas the growth rate of 〉1.0×109 s−1 for the radical is much faster than the decay rate of (1.8±0.3)×108 s−1 for the precursor fluorescence in dissociation of p-methoxybenzyl alcohol. The formation of the radical depends linearly on the photolysis pulse fluence for dissociation of p-methoxytoluene and p-methoxybenzyl alcohol. The data show existence of two distinct dissociation channels. p-Methoxytoluene dissociates from thermally equilibrated levels of the S1 state after vibrational relaxation, whereas p-methoxybenzyl alcohol dissociates from vibrationally excited levels of the S1 state in competition with vibrational relaxation. The difference of these channels is explained on a model of electronic coupling between the precursor and product states in the geometry where the C–H and C–O bonds are stretched in a plane perpendicular to the benzene rings. For p-methoxytoluene, the S1 state does not correlate adiabatically to the ground state of the C–H bond fission products, so intersystem crossing or internal conversion precedes dissociation. For p-methoxybenzyl alcohol, avoided crossing between the ππ* (benzene) configuration and the np(O)σ*(C–O) repulsive configuration results in the adiabatic potential-energy surface which evolves to the ground state of the C–O bond fission products allowing rapid dissociation. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 1359-1365 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The photodissociation of diphenylmethane by excitation to the S1 state at 266 nm in n-heptane solution is studied by nanosecond fluorescence and absorption spectroscopy. The formation of the diphenylmethyl radical is identified by its fluorescence, which is induced by excitation at 308 nm, and by its absorption. The growth rate of (3.7±0.4)×107 s−1 for the radical is equal to the decay rate of (3.8±0.4)×107 s−1 for the precursor fluorescence. The quantum yield of the radical is of the order of ∼10−3. Neither dissociation to the radical nor intersystem crossing to the T1 state is thermally activated, whereas activated internal conversion to the S0 state is observed. The formation of the radical depends linearly on the photolysis pulse fluence. The data are consistent with a mechanism that the molecule undergoes intersystem crossing from thermally equilibrated levels of the S1 state to vibrationally excited levels of the T1 state at which it dissociates in competition with vibrational relaxation. The mechanism is explained in terms of electronic coupling between the precursor and product states. The S1 state does not correlate adiabatically to the ground state of the C–H bond fission products, so intersystem crossing to the T1 state precedes dissociation. In the T1 state, avoided crossing between the ππ* (benzene) configuration and the σσ* (C–H) repulsive configuration results in the adiabatic potential energy surface which evolves to the ground state of the C–H bond fission products allowing rapid dissociation. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 45 (1994), S. 0 
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The day and night pattern of upstream and downstream dispersal of masu salmon fry of wild and domestic origin was compared in artificial channels (45 m long), for two ages of planting: unfed alevins and eyed eggs. Early dispersal was important for the wild stock (48–50%) compared with the domestic one (16–36%). More wild fry moved downstream than upstream, and more domestic fry dispersed upstream. Upstream movement in wild and domestic fry was more active by day than by night, except for wild fry planted as eyed eggs, where upstream migration was higher at night. In contrast, downstream movement in wild and domestic fry was more common by night than by day, but daylight catches were not negligible for the wild stock.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1546-1718
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Medizin
    Notizen: [Auszug] The rat small eye strain (rSey) lacks eyes and nose in the homozygote, and is similar to the mouse Sey strain with mutations in the Pax-6 gene. We isolated Pax-6 cDNA clones from an rSey homozygote library, and found an internal deletion of about 600 basepairs in the serine/threonine-rich domain. ...
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Amino acids 1 (1991), S. 375-378 
    ISSN: 1438-2199
    Schlagwort(e): Amino acids ; Cysteic acid analysis ; Taurine analysis ; Gas chromatography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We have reported preparations and gas chromatographic analyses of volatile derivatives of sulfuric acid and taurine (Masuoka et al., 1988; 1989). By extending these studies, we have developed a method for the gas chromatographic determination of cysteic acid. Cysteic acid was converted to the N-isobutoxycarbonyl derivative by the reaction with isobutyl chloroformate in the presence of sodium hydroxide. After desalting with a cation-exchange column, the derivative was converted to the silver salt by reacting with silver oxide. The resulting silver salt was quantitatively esterified with methyl iodide in the presence of dimethyl sulfate and silver oxide. Dimethyl N-isobutoxy-carbonylcysteate [methyl 2-(N-isobutoxycarbonylamino)-3-(methoxysulfonyl) propanoate] formed was analyzed by gas chromatography. The calibration curve was linear up to 5.0µmol per ml of cysteic acid and the recovery was more than 95%.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1572-9591
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract The largest superconducting fusion machine, Large Helical Device (LHD), is now under construction in Japan and will begin operation in 1997. Design and construction of related R&D programs are now being carried out. The major radius of this machine is 3.9 m and the magnetic field on the plasma center is 3 T. The NbTi superconducting conductors are used in both helical coils and poloidal coils to produce this field. This will be upgraded in the second phase a using superfluid coil cooling technique. A negative ion source is being successfully developed for the NBI heating of LHD. This paper describes the present status and progress in its experimental planning and theoretical analysis on LHD, and the design and construction of LHD torus, heating, and diagnostics equipments.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 64 (1999), S. 144-147 
    ISSN: 1432-0827
    Schlagwort(e): Key words: Osteoporosis — Leprosy — Hypogonadism — Male.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract. We measured the bone mineral density (BMD) of 353 leprosy patients (197 males 50–89 years old, average age 70.2; and 156 females 53–90 years old, average age 72.9) and serum levels of free testosterone (FT) in 81 males. The BMD of the lumbar vertebrae (L2–L4), diaphysis of the radius (1/3 radius), and the neck of the femur (neck) was measured using DXA (QDR 4500). The BMD of −2.5 SD YAM (young adult mean) in Japanese men and women was used as the cutoff value for osteoporosis in the respective genders: BMD of L2–L4, 0.751 g/cm2 (male), 0.747 g/cm2 (female); 1/3 radius, 0.655 g/cm2 (male), 0.550 g/cm2 (female); neck, 0.581 g/cm2 (female). The percentages of males with osteoporosis were 31.3% in the 50th, 32.9% in the 60th, 44.9% in the 70th, and 40.7% in the 80th decade at L2–L4. Similarly, the percentages were 33.3%, 58.3%, 74.3%, and 75.0%, respectively, at 1/3 radius. Among females, the percentages were 22.2%, 41.3%, 44.9%, and 68.8%, respectively, at L2–L4; 0%, 42.9%, 89.5%, and 78.6%, respectively, at 1/3 radius; and 11.1%, 38.6%, 67.7%, and 84.6% respectively, at neck. FT in men ranged from almost 0 to normal at each decade and BMD levels were significantly correlated with FT in all three regions of the skeleton (P 〈 0.0001). More than 30% of osteoporosis was found at each decade and FT may be one of the main factors affecting BMD in male leprosy patients.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1432-1114
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract This article presents a simple technique for temperature visualization using liquid crystals in an aqueous solution during the process of cooling and solidification. This method provides a clear picture of the role of double-diffusive convection in producing vertical compositional and density stratification in an initially homogeneous liquid during solidification.
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