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  • Digitale Medien  (25)
  • 1995-1999  (25)
  • 1999  (15)
  • 1998  (10)
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 29-37 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The upconversion emission intensities of Er3+ ion around 550 and 660 nm in fluorozirconate glasses were measured under 800 nm excitation. Though energy transfer processes played an important role in upconversion mechanism at high concentration of ErF3, those have not been treated quantitatively. The energy transfer rates were calculated from the optical parameters assuming some distribution of Er3+ ions. We calculated the upconversion intensities around 550 and 660 nm by using rate equations. It was found that the dependence of upconversion emission intensities on the ErF3 concentration could be reproducible and the principal upconversion mechanism could be evaluated. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 6262-6267 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A mechanism explaining the breakdown of dielectrics with high intrinsic inhomogeneity like natural rocks and concrete is proposed and proved experimentally. This work has a very promising industrial application in the drilling and demolition of natural and artificial solid materials by electric pulses. The mechanism includes the breakdown of gas cavities inside the dielectric and on its surface. At a very high applied voltage, the high electric field causes the breakdown in the cavities. The displacement and conduction currents flowing through a number of such cavities result in the heating of the plasma and high pressure pulse generation. The pulsed pressure results in crack formation and finally, in the destruction of a solid material. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 6143-6149 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Er3+ singly- and Er3+/Yb3+-codoped fluorozirconate glasses were prepared. The upconversion emission intensities of the Er3+ ion around both 550 and 660 nm were measured under 800 nm excitation. The absorption band of the Yb3+ ion is located around 980 nm. Though the absorption band of Yb3+ does not interact directly with the incident light at 800 nm, both upconversion intensities around 550 and 660 nm emission increased with the increasing YbF3 concentration. We calculated the upconversion intensities around 550 and 660 nm by using rate equations and evaluated the principal upconversion mechanism in Er3+ singly- and Er3+/Yb3+-codoped samples quantitatively. We also investigated the reason for the increase of the upconversion emission intensities with the codoping of Yb3+ under 800 nm excitation. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 26 (1999), S. 0 
    ISSN: 1365-2842
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The authors attempted to clarify the primary factors affecting the timing of the initial electromyographic discharges in the jaw depressor muscles (EMG onset). The changes in EMG onset in the inferior head of the lateral pterygoid (Lpt) and the anterior belly of the digastric muscles (Dig) were measured by varying duration of the open–close movement or occlusal force during the open–close–clench cycle (OCC). EMG onset tended to precede the beginning of the opening movement during OCC. The duration of opening and closing phase and the duration of occluding phase showed no significant correlation with the time-lag between EMG onset and the beginning of the opening movement (onset time).The mean EMG activity of the masseter muscle (Mm), corresponding to the occlusal force, showed a highly significant correlation with the onset time. The maximal opening velocity was highly correlated with the mean EMG activity of the jaw depressors before jaw opening. In conclusion, it was found that occlusal force is a major factor in EMG onset in the jaw depressors. It is suggested that smooth opening needs tooth contact with some degree of occlusal force.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The origin of the cosmic X-ray background radiation, has remained mysterious since its discovery thirty-five years ago. Investigation of its origin has been difficult because instruments have had insufficient resolution to distinguish small, faint sources in the hard X-ray band (above ...
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Journal of cancer research and clinical oncology 125 (1999), S. 646-652 
    ISSN: 1432-1335
    Schlagwort(e): Key words Osteosarcoma ; CD44 ; Immunohisto-chemistry ; Prognosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The standard form of CD44 (CD44H) is a transmembranous glycoprotein, widely distributed on a variety of human lymphoid cells, epithelial cells and tumours. CD44 has many variant forms, which are generated by alternative splicing. In recent years, CD44 has been reported to be related to the degree of tumour differentiation, tumour cell invasion, and metastasis. We investigated 44 tumour specimens in 39 patients with osteosarcoma immunochemically to analyse the expression of CD44 standard (CD44H) and variant exon-encoded gene products (CD44v3, v4, v5, v6, v7, v9, and v10). Furthermore, the relationship between CD44 expression and the clinical outcome of patients with osteosarcoma was analysed. Membrane accentuation and exclusive cytoplasmic reactivity were analysed as separate staining patterns. Tumour cells and some multinucleated giant cells were markedly stained. CD44H, v3, v4, v5, v6, v7, v9, and v10 were expressed in 85%, 49%, 54%, 59%, 46%, 5%, 28%, and 10% of the specimens respectively. The cumulative 5-year metastasis-free survival was 58% in CD44v6-negative cases and 24% in CD44v6-positive cases (P=0.046). However, the cumulative 5-year metastasis-free survival was not significantly different between cases positive and negative for other variants of CD44. Multivariate analysis (Cox proportional-hazard model) with CD44v6 expression (positive or negative), chemotherapy (intensive or non-intensive), tumour site (proximal or distal), and age (at least 30 years or less than 30 years) showed that expression of CD44v6 and chemotherapy were important prognostic factors in patients with osteosarcoma. Overexpression of CD44 isoforms containing variant v6 is correlated with poor prognosis in patients with osteosarcoma.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1437-7799
    Schlagwort(e): Key words SMP30 ; Calcium efflux ; Tubular epithelia ; Calcium pump ; Calmodulin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Background. Senescence marker protein-30 (SMP30), a calcium binding protein, is preferentially expressed in the renal proximal tubules and hepatocytes and is presumed to play a role in Ca2+ homeostasis. Methods. To explore its physiological functions in the tubular cells, we investigated the effect of SMP30 on Ca2+ efflux via the ATP-dependent plasma membrane calcium pump. LLC-PK1 cells were stably transfected with a cDNA encoding SMP30, and the established transfectants were subjected to ATP responses. Results. Overexpression of SMP30 significantly increased Ca2+ efflux under both basal and ATP-stimulated conditions. Inhibition of calmodulin by trifluoperazine abrogated the enhanced Ca2+ efflux, suggesting that SMP30 activated the calmodulin-dependent Ca2+ pump. It is known that Ca2+ superfluous influx induces cellular injury. Compared with mock-transfected cells, LLC-PK1 cells expressing SMP30 showed resistance to cellular death triggered by Ca2+ superfluous influx. Conclusion. These results suggest the possibility that, in renal tubular cells, endogenous SMP30 participates in Ca2+ efflux via activating the calmodulin-dependent Ca2+ pump and thereby confers resistance of the cells against injury caused by high intracellular Ca2+ concentrations.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Archives of orthopaedic and trauma surgery 118 (1998), S. 136-139 
    ISSN: 1434-3916
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We performed five reconstructions by bone transport in patients with bone sarcoma: three osteosarcomas, one Ewing’s sarcoma and one chondrosarcoma. Four sacromas were in the distal femur and one in the shaft of the tibia. Four patients received multidrug chemotherapy. The average length of the skeletal defect after tumour resection was 17 (range 10–25) cm. All patients underwent double elongation from both proximal and distal sites of the bone defect. The average follow-up period was 48 (range 40–66) months, and the average duration of external fixation was 32 months (range 579–1340 days). In one case, bone formation was satisfactory, but in the other cases, it was poor and slow. The average treatment index was 95 (range 53–191) days per 1 cm of elongation. In one case, the bone fragment disappeared during the bone transport. In one case, the end of the bone protruded from the skin, and osteomyelitis set in. This patient underwent above-knee amputation due to failure of infection control. Three patients suffered talipes equinus. One patient died of pulmonary metastasis. Two patients had fair and three had poor function. This method is not recommended for patients with bone sarcoma who may have a poor prognosis, as it has an unacceptably high complication rate.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1432-069X
    Schlagwort(e): Key words Alginate oligosaccharides ; Collagen ; Human skin fibroblasts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Effects of alginate oligosaccharides on cell proliferation and expression of collagen in cultured skin fibroblasts were studied. The oligosaccharides were found to suppress fibroblast proliferation to half the level in control cultures at a dose of 10 mg/ml during a period of 5 days. The inhibition was accompanied by a change in cell shape. The inhibition of cell proliferation was reversible, since depletion of these oligosaccharides led to a recovery of cell motility. Treatment of confluent cells with 10 mg/ml oligosaccharides for 5 days resulted in a reduction in collagen synthesis to one half of that in control cultures and inhibition of steady state levels of α1(I), α2(I), α1(III) and α1(VI) collagen mRNAs. These results suggest that alginate oligosaccharides are potential modulators of dermal fibroblasts and may provide a useful tool for the treatment of disorders related to abnormal collagen metabolism.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1432-0630
    Schlagwort(e): PACS: 61.16.-d; 68.35.Bs; 73.20.At
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: 9  atoms/cm2. In this study, in order to achieve an elementary analysis of each atom on the Si surface, metal atoms on the Si(001) surface are analyzed by STS and the result is evaluated with the first principles calculations of quantum mechanics. As metallic contaminations, sub-monolayer of Aluminum is evaporated on Si(001)2×1. The Local Density of State (LDOS) on the Al/Si(001)2×1 is measured by STS at room temperature. The measured LDOS at an Al dimer is in good agreement with that obtained from the calculation.
    Materialart: Digitale Medien
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