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  • 1
    Digitale Medien
    Digitale Medien
    Light-illumination-induced transformation of electron traps in hydrogen-implanted n-type silicon (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5630-5635 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Light-illumination-induced transformation of electron traps in 170 keV hydrogen-implanted n-type silicon with a dose of 2×1010 cm−2 has been studied with deep level transient spectroscopy for fabricated gold Schottky diodes. In addition to the well-known vacancy-related traps, two hydrogen-related E(0.32) and E(0.49) traps are produced by hydrogen implantation. It is observed that the concentration of vacancy-related traps decreases with illumination of light with a photon energy above the band-gap energy in zero-biased Schottky diodes, while that of hydrogen-related traps increases. No effects of light illumination are found in reverse-biased diodes. It is suggested that the vacancy–oxygen pair is transformed into the E(0.32) trap by adding hydrogen which is liberated from shallow-level, hydrogen-containing defects. The hydrogen liberation is thought to occur through induced instability of them by changing their charge states with electron capture. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.371572
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  • 2
    Digitale Medien
    Digitale Medien
    Estimation of the degree of acclimatization to high altitude by a rapid and simple physiological examination (1995)
    Springer
    International archives of occupational and environmental health 67 (1995), S. 347-351 
    Details
    ISSN: 1432-1246
    Schlagwort(e): High altitude ; Acclimatization ; Pulse oximetry ; Exercise ; Arterial hemoglobin saturation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The recent expansion in the geographical areas open to human activity has made it desirable to have an objective method to evaluate the degree of high-altitude acclimatization. In this study, we measured the arterial oxygen saturation value at rest and just after exercise in healthy high-altitude trekkers using a transportable pulse oximeter. During a 100-day stay at high altitude (around 4000 m), the degree of arterial hemoglobin saturation measured at rest was relatively stable. However, shortly after arrival at high altitude, even light exercise induced an acute reduction in the degree of arterial hemoglobin saturation; this reduction was ameliorated as the trekkers became acclimatized to the high altitude. Preliminary short trekking to high altitudes does not appear sufficient to induce this response. It is suggested that this rapid and simple physiological examination, the measurement of arterial oxygen saturation value after light exercise, could be a convenient means of estimating the level of high-altitude acclimatization among healthy subjects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00385651
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  • 3
    Digitale Medien
    Digitale Medien
    Rate pressure product and oxygen saturation in tourists at approximately 3000 m above sea level (1998)
    Springer
    International archives of occupational and environmental health 71 (1998), S. 520-524 
    Details
    ISSN: 1432-1246
    Schlagwort(e): Key words Master's two-step test ; Mountain sickness ; Ischemic heart disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: AbstractObjectives: Using modern transportation technology, many travelers easily access moderate altitudes of approximately 3000 m above sea level. In the present study the effects of this altitude on cardiovascular parameters were studied among office workers dwelling at sea level. Methods: Heart rate, blood pressure, arterial oxygen saturation (SpO2), and electrocardiography were monitored before and after Master's double-step exercise at 2700 and 3700 m. The test consisted of stepping onto and off of two 23-cm steps for 3 min at a predefined rate. Results: The resting values recorded for the heart rate and mean blood pressure at 2700 and 3700 m did not statistically significantly differ from those noted at sea level. However, the increases in these values after exercise were significantly greater at high altitude. The rate pressure product more than doubled after exercise at 3700 m. Electrocardiographic abnormalities were observed in some cases. The postexercise blood lactate concentration was significantly higher at 3700 m than at sea level or at 2700 m, suggesting that the oxygen supply-demand relationship was not balanced at this altitude. Furthermore, exercise provoked an acute reduction in SpO2 at 2700 and 3700 m but showed no effect at sea level. Conclusion: These observations suggest that the oxygenation status of the heart might be at risk in many travelers and workers during and after exercise load at an altitude of approximately 3000 m.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004200050317
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  • 4
    Digitale Medien
    Digitale Medien
    Alteration of regional brain oxygen saturation (rSO2) in a patient with cerebral damage after aortic arch replacement: carbon dioxide reactivity monitored by near-infrared spectroscopy suggested inverse steal phenomenon (1998)
    Springer
    Journal of anesthesia 12 (1998), S. 106-108 
    Details
    ISSN: 1438-8359
    Schlagwort(e): rSO2 ; hyperventilation ; Cerebrovascular response
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02480782
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  • 5
    Digitale Medien
    Digitale Medien
    Neuromuscular effects of sevoflurane in patients with myasthenia gravis (1996)
    Springer
    Journal of anesthesia 10 (1996), S. 157-162 
    Details
    ISSN: 1438-8359
    Schlagwort(e): Myasthenia gravis ; Sevoflurane ; Neuromuscular function ; T1 ; TOFR
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The current study evaluated the neuromuscular responses following administration of sevoflurane in 14 patients with myasthenia gravis (MG) (I–IIb in Osserman's classification) scheduled for thymectomy and in 11 control patients (ASA I–II) who underwent elective surgery. The electromyographic (EMG) response of the abductor digiti minimi was measured following train-of-four (TOF) stimulation of the ulnar nerve every 20 s. After induction of anesthesia with a combination of 3–4 mg·kg−1 thiopental and 1–2 μg·kg−1 fentanyl with 66% N2O and oxygen, an inspired concentration of 4% sevoflurane was administered via a face mask for 7 min. Anesthesia was maintained during surgery with 66% N2O in oxygen and with 1 minimum alveolar concentration (MAC) of end-tidal concentration of sevoflurane. The T1 (the amplitude of the first response) values decreased more profoundly in the MG patients than in the control patients at the end of surgery (P〈0.05). Following administration of 4% sevoflurane for 7 min, the TOFR (the ratio of the fourth TOF to the first response) values revealed depressions greater than 10% of preinhalation values in 11 of 14 MG patients with a marked individual variation. This attenuated response was followed by a further depression of the TOFR values with increasing time of 1 MAC sevoflurane anesthesia. On the other hand, no notable changes were observed in patients with normal neuromuscular functions. The most significant factor that correlated with the depression of the TOFR values induced by 1 MAC sevoflurane was the anti-AchR antibody titers (P=0.029). Our results indicate that MG patients have an increased neuromuscular sensitivity to sevoflurane.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02471383
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  • 6
    Digitale Medien
    Digitale Medien
    Ca2+-activated K+-channels in the nuclear envelope isolated from single pancreatic acinar cells (1995)
    Springer
    Pflügers Archiv 430 (1995), S. 148-150 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Nuclear envelope ; Patch-clamp technique ; Ca2+-activated K+-channels ; Pancreatic acinar cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The patch-clamp techniques are applied to the outer membrane of the nuclear envelope isolated from rat pancreatic acinar cells. The nucleus identified under an inverted microscope was removed by cell surgery from enzymatically dispersed single cells. All the patch-clamp techniques, in situ, excised, and whole-material recordings were applied to the envelope. We have found voltage- and Ca2+-activated K+-channels with an unitary conductance of 200 pS in the outer membrane. The channels are activated by lumen positive potentials and by an increase in luminal Ca2+ concentration. They may play a role for controlling Ca2+-release from the lumen of the nuclear envelope (endoplasmic reticulum) to the nucleoplasm and the perinuclear cytoplasm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00373851
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  • 7
    Digitale Medien
    Digitale Medien
    Ca2+-dependent unidirectional vesicular release detected with a carbon-fibre electrode in rat pancreatic acinar cell triplets (1994)
    Springer
    Pflügers Archiv 428 (1994), S. 69-75 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Polarized secretion ; Pancreatic acinar cells ; Oxidation currents ; Carbon fibre electrode ; Ca2+-dependent exocytosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract An amperometric constant-voltage method for detection of serotonin oxidation currents was applied to pancreatic acinar cell triplets to determine the site of release of granular content following an increase in [Ca2+]i. The carbon fibre electrode, fabricated to be compatible with a conventional patch-clamp amplifier, was voltage-clamped at 600 mV exceeding the serotonin oxidation voltage, 300 mV. The electrode was placed on the different regions of cell surface of acinar cell triplets loaded with exogenous serotonin. Transient oxidation currents were detected only when the electrode was placed on the acinar lumen after stimulation with a Ca2+ ionophore, A23187, but never observed on the basal or lateral cell surface, or paracellular clefts. No such current responses were observed in the acinar cells without serotonin loading. The results indicate that the A23187-induced sustained increase in [Ca2+]i discharges serotonin specifically into the lumen, and provides direct evidence for the presence of Ca2+-dependent unidirectional release of granular contents in pancreatic acinar cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00374753
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