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  • 11
    Electronic Resource
    Electronic Resource
    Electrochemical observation of instabilities of the Belousov-Zhabotinskii reaction in CSTR (1994)
    Springer
    Journal of applied electrochemistry 24 (1994), S. 647-651 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The instabilities of the Belousov-Zhabotinskii reaction were studied in an isothermal CSTR by varying the space velocity as bifurcation parameter. The time-dependent concentration of bromide ion and redox potential were observed, respectively, by a Ag-AgBr electrode and a platinum-wire electrode under reaction-controlling conditions. The single-peak periodic and the chaotic oscillations occur alternately with increasing space velocity. The multipeak oscillations were also observed at higher space velocities. Two kinds of chaotic oscillations were observed, chaotic oscillations with amplitudes varying irregularly in the periodic-chaotic sequence region and chaotic mixing of large and small amplitude in the multipeak oscillations region. An analysis of the phase portraits for these chaotic oscillations indicates that they correspond to low dimensional and fractal structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00252090
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  • 12
    Electronic Resource
    Electronic Resource
    Nonlinear processes in UV optical materials at 248 nm (1990)
    Springer
    Applied physics 50 (1990), S. 55-59 
    Details
    ISSN: 1432-0649
    Keywords: 42.55.Gp ; 42.55.Rz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nonlinear processes in UV optical materials were investigated by using 280-fs, 248-nm pulses. Nonlinear absorption in CaF2 was confirmed to be a two-photon process by using the luminescence of self-trapped excitons, which was also used for the single shot pulse width measurement. The absorption bands due to F centers were identified in CaF2, MgF2, and LiF after several hundred shots at 100 GW/cm2. Absorption at 248 nm was considerable especially in MgF2 and LiF. Self-focusing and self-phase modulation were observed in CaF2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330094
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  • 13
    Electronic Resource
    Electronic Resource
    Gas density measurement of pulsed gas jets using XeF four-photon fluorescence induced by a KrF laser (1992)
    Springer
    Applied physics 55 (1992), S. 323-326 
    Details
    ISSN: 1432-0649
    Keywords: 34.00 ; 42.55.Gp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The gas densities of two pulsed gas jets were measured together with spatial and temporal distributions by the XeF fluorescence induced by a KrF laser. The B-X and C-A transitions of XeF showed a biquadratic dependence on laser intensity when SF6 was used as the F donor instead of F2, and quadratic and cubic dependences on gas density, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333074
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  • 14
    Electronic Resource
    Electronic Resource
    Phase advances of circadian rhythms in somatostatin depleted rats: effects of cysteamine on rhythms of locomotor activity and electrical discharge of the suprachiasmatic nucleus (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 677-685 
    Details
    ISSN: 1432-1351
    Keywords: Circadian rhythm ; Suprachiasmatic nucleus ; Cysteamine ; Somatostatin ; Brain slice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Somatostatin is synthesized in the suprachiasmatic nucleus (SCN), a circadian pacemaker in mammals. To explore the functional significance of somatostatin in the circadian system, we examined rhythms of rat locomotor activity and electrical firing rate of SCN neurons in the brain slice after temporal depletion of somatostatin levels in the SCN. Intraperitoneal administration of cysteamine (200 mg/kg), a somatostatin depletor, significantly reduced somatostatin level in the in vivo SCN 5 min after injection and kept low level as long as 3 to 4 days. This administration, on the other hand, induced significant phase advances of about 51 min in the subsequent free-running rhythm of locomotor activity of the rat. A marked phase advance in the circadian rhythm of firing rate in the SCN was also observed after administration of cysteamine in coronal hypothalamic slices. These persistent phase shifts after administration of a somatostatin depletor may suggest that the change of somatostatin level in the SCN have a feedback influence on the circadian pacemaker.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191840
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  • 15
    Electronic Resource
    Electronic Resource
    Enhancement of protein secretion by optimizing protein synthesis: isolation and characterization of Escherichia coli mutants with increased secretion ability of alkaline phosphatase (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 163-169 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Overexpression of the Escherichia coli phoA gene, coding for alkaline phosphatase, on multicopy plasmids caused the accumulation of the precursor form of alkaline phosphatase. The cells lost their viability by a half-life of 60 min and exhibited high sensitivity to 1% sodium dodecyl sulfate (SDS), suggesting that the assembly of the surface proteins were affected by overexpression of the phoA gene. From the cells exhibiting resistance to 1% SDS, we obtained 20 mutants that secrete more alkaline phosphatase into the periplasmic space. Three representatives of the mutants accumulated no precursor molecules and secreted alkaline phosphatase by five- to six-fold that of the wild-type cells carrying multicopy phoA. In all of the three mutants, the amount of phoA transcripts were two to four times less than those in the wild-type cells, indicating that the ability to secrete a large amount of alkaline phosphatase was conferred by decreasing the synthetic rates of the phoA gene product. When the promoter of phoA was replaced with the tacI promoter and the expression level of the phoA gene was regulated with isopropyl-1-thio-β-d-galactoside, the secretion of alkaline phosphatase into the periplasm decreased as the synthetic rate of the phoA gene product increased over a threshold. All these results indicate that overproduction of the phoA gene product causes defects in the secretion of alkaline phosphatase and that the regulation of the expression level is essential for efficient translocation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00186954
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  • 16
    Electronic Resource
    Electronic Resource
    Enhancement of protein secretion by optimizing protein synthesis: isolation and characterization of Escherichia coli mutants with increased secretion ability of alkaline phosphatase (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 163-169 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Overexpression of the Escherichia coli phoA gene, coding for alkaline phosphatase, on multicopy plasmids caused the accumulation of the precursor form of alkaline phosphatase. The cells lost their viability by a half-life of 60 min and exhibited high sensitivity to 1% sodium dodecyl sulfate (SDS), suggesting that the assembly of the surface proteins were affected by overexpression of the phoA gene. From the cells exhibiting resistance to 1% SDS, we obtained 20 mutants that secrete more alkaline phosphatase into the periplasmic space. Three representatives of the mutants accumulated no precursor molecules and secreted alkaline phosphatase by five- to six-fold that of the wild-type cells carrying multicopy phoA. In all of the three mutants, the amount of phoA transcripts were two to four times less than those in the wild-type cells, indicating that the ability to secrete a large amount of alkaline phosphatase was conferred by decreasing the synthetic rates of the phoA gene product. When the promoter of phoA was replaced with the tacI promoter and the expression level of the phoA gene was regulated with isopropyl-1-thio-β-D-galactoside, the secretion of alkaline phosphatase into the periplasm decreased as the synthetic rate of the phoA gene product increased over a threshold. All these results indicate that overproduction of the phoA gene product causes defects in the secretion of alkaline phosphatase and that the regulation of the expression level is essential for efficient translocation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050125
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  • 17
    Electronic Resource
    Electronic Resource
    Salivary cortisol for monitoring circadian rhythm variation in adrenal activity during shiftwork (1993)
    Springer
    International archives of occupational and environmental health 64 (1993), S. 499-502 
    Details
    ISSN: 1432-1246
    Keywords: Salivary cortisol ; Circadian rhythm ; Shiftwork
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To examine the validity of salivary cortisol for monitoring circadian rhythm variation in adrenal activity during shiftwork, saliva and blood samples were collected at 4-h intervals in experimental short-term shifts, i.e., day (work 0830–1600 h; sleep 0030–0800 h), evening (work 1630–2400 h; sleep 0430–1200 h), and night (work 0030–0800 h; sleep 1230–2000 h) shifts over 2 days. Cortisol levels, determined by radioimmunoassay, and the circadian profiles of saliva and sera were compared. The salivary cortisol showed relatively low levels, the 2-day mean value being 3.1%–3.3% that of serum total cortisol through all shifts. Significant differences in the serum to saliva cortisol ratios were noted among shifts and subjects. When expressed as a relative percentage of a 2-day mean value, however, salivary cortisol paralleled the modified circadian profiles of serum total cortisol of the evening and night shifts, with no significant time lag and no difference in magnitude. The cosinor analysis supported this finding. Thus, salivary cortisol appears to be an excellent measure for monitoring circadian rhythm variation in adrenal activity in healthy individuals during shiftwork.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381098
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  • 18
    Electronic Resource
    Electronic Resource
    Temporary threshold shift of temperature sensation caused by vibration exposure (1992)
    Springer
    International archives of occupational and environmental health 63 (1992), S. 531-535 
    Details
    ISSN: 1432-1246
    Keywords: Human skin ; Temperature sensation ; Vibration exposure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The temporary threshold shift of temperature sensation due to vibration exposure was studied to clarify the significance of frequency and acceleration on it. The discrete frequencies of the vibrations tested were 32, 63, 125, 250 and 500 Hz, and the accelerations were at the level of 2, 4, 8 and 16 g. The threshold shift of warm sensation (TTSw) was markedly, but that of cool sensation was small and not significantly different from the control value. TTSw increased with a rise in the level of acceleration and was largest at 125 Hz among the frequencies examined. The most effective frequency among the vibrations tested for warm sensation was inferred to be lower than that for vibratory sensation. After exposure, TTSw or the increment of the neutral zone decayed exponentially but bounced slightly in the later period. These patterns of TTSw are similar to those of the vibration-induced TTS of vibratory sensation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386341
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  • 19
    Electronic Resource
    Electronic Resource
    Reductions in recruitment force thresholds in human single motor units by successive voluntary contractions (1990)
    Springer
    Experimental brain research 82 (1990), S. 227-230 
    Details
    ISSN: 1432-1106
    Keywords: Motor units ; Voluntary contraction ; Muscle force ; Potentiation ; Stretch reflex ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recruitment force thresholds of biceps brachii single motor units were studied in 4 male subjects before and after an isometric muscle contraction, passive muscle stretch, or following successive muscle contractions, muscle stretches or during alternations between muscle stretches and muscle contractions. Isometric muscle contractions of 5 s duration decreased subsequent single motor unit force thresholds. These force thresholds could usually be reset at or near precontraction force threshold values by passive muscle stretch induced by elbow extension. Single motor units showing reduced force thresholds following contraction were momentarily derecruited during and/or after muscle stretch. Successive muscle stretches alone did not significantly alter single motor unit force thresholds. In contrast, single motor unit recruitment force thresholds during successive weaker contractions were progressively lowered. Intercontraction muscle stretches maintained the single motor unit force thresholds at or near the initial force threshold level. The mechanism(s) underlying a muscle contraction-induced lowering of single motor unit force thresholds may reside in stretch reflex pathways.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230858
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  • 20
    Electronic Resource
    Electronic Resource
    Detection of manganese superoxide dismutase mRNA in the theca interna cells of rat ovary during the ovulatory process by in situ hybridization (1994)
    Springer
    Histochemistry and cell biology 102 (1994), S. 173-176 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract To determine the possible involvement of reactive oxygen species in ovulation, dynamic aspects of superoxide dismutase (SOD) isozyme were studied in the ovaries of rats by in situ hybridization histochemistry. Previously, mRNA levels of ovarian manganese superoxide dismutase (Mn-SOD) were reported markedly to increase whilst enzymic activity of Mn-SOD decreased during the ovulatory process after treating immature rats with 10 and 5 Units, respectively, of pregnant mare serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG). Levels of Cu/Zn-SOD activity and Cu/Zn-SOD mRNA were reported to remain unchanged throughout ovulation. This increase in the Mn-SOD mRNA level was shown in the present study by in situ hybridization to be localized to the theca interna cells throughout the PMSG/HCG-induced ovulatory process. The observations suggest that the turnover rate of Mn-SOD but not Cu/Zn-SOD increases specifically in the mitochondria of these cells. SOD has been postulated to play important roles in steroidogenesis. The relationship is discussed between mitochondrial functions in steroid-secreting cells and superoxide radicals and related metabolite(s).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00268893
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