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  • 1995-1999  (4)
  • 1990-1994  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 305-307 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A reliable process has been developed for the fabrication of multilevel single-electron tunneling (SET) devices. Using this process, we have fabricated SET devices with Au-SiO-Al and Al-AlOx-SiO-Al overlap capacitors. The SET transistors exhibit voltage gain and, despite the complex device structure, have a low charge noise (7×10−5e/(square root of)Hz). Moreover, the use of overlap capacitors in SET devices results in a reduction of cross capacitances down to 8%. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2014-2016 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A single-electron tunneling transistor has been directly coupled on-chip to a high electron mobility transistor. The high electron mobility transistor (HEMT) is used as an impedance matching circuit with a gain close to unity. The HEMT transformed the 1.4 MΩ output impedance of the single electron tunneling (SET) transistor by two orders of magnitude down to 5 kΩ, increasing its bandwidth to 50 kHz. This circuit makes it possible to observe the motion of individual electrons at high frequencies. The requirements for the bandwidth in high frequency applications is discussed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Annals of oncology 8 (1997), S. 1023-1029 
    ISSN: 1569-8041
    Keywords: double-staining ; glioma ; growth factors ; immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Growth factors play a role in proliferation and motility of malignant glial cells, through autocrine and paracrine mechanisms. Also, proliferation of non-tumour cells, e.g., endothelial cells, is likely to be controlled by growth factors. Several growth factors with their appropriate receptors can be involved, but studies on tissue specimens evaluating this in glioma are rare. Materials and methods: We evaluated the potential role of Transforming growth factor-α (TGF-α) and Epidermal growth factor receptor (EGF-R), the Platelet-derived growth factor A- and B-chain (PDGF-A and PDGF-B) and its receptors (PDGFRα and PDGFRβ), and basic fibroblast growth factor (bFGF) in gliomas by analysing 86 of these tumours on the single cell level for the presence of immunoreactive growth factors and receptors. In a few cases double-staining experiments were done to directly visualize co-expression of factor and receptor. Results: Multiple growth factors and their receptors are present in astrocytic tumours; the higher the grade, the more growth factors and the more positive cells are found. Oligodendroglial tumours and pilocytic astrocytomas showed little expression. Autocrine and paracrine mechanisms were frequently possible in the astrocytic tumours, often more than one loop could be involved. Interestingly, it was also frequently possible that non-tumour cells produced a growth factor for which the tumour cells expressed the receptor. Conclusions: Multiple growth factors appear to be involved in astrocytic tumours, with frequent autocrine and paracrine loops. Expression of these molecules seems to increase with increasing grade. The results argue for a contribution of non-tumour cells to the growth of a tumour.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical microbiology & infectious diseases 9 (1990), S. 864-868 
    ISSN: 1435-4373
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Sequences derived from the endogenous plasmid ofChlamydia trachomatis and from the genes coding for ribosomal 16S RNA ofChlamydia psittaci were used as primers and oligonucleotide probes for detection of chlamydiae by the polymerase chain reaction. The endogenous plasmid primers generated specific amplified products of 517 bp with all knownChlamydia trachomatis serovars. No specific products ofChlamydia psittaci andChlamydia pneumoniae could be detected using these primers. With the rRNA primers specific amplified products of 208 bp were generated withChlamydia psittaci, Chlamydia trachomatis andChlamydia pneumoniae. No specific amplified products were detected with DNA isolated from a variety of microorganisms from the urogenital and the respiratory tract. Of 156 clinical specimens used for evaluation of the polymerase chain reaction, 26 were found to be positive forChlamydia trachomatis on culture. All 26 culture positive samples were also found to be positive forChalmydia trachomatis DNA by the polymerase chain reaction with both primer sets. Two culture negative samples were also found to be positive by this technique. The polymerase chain reaction thus seems to be a sensitive and reliable method for detection ofChlamydia trachomatis.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 40 (1995), S. 609-614 
    ISSN: 1573-2568
    Keywords: serology ; gastritis ; Helicobacter pylori ; healthy volunteers ; pepsinogens ; gastrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study was undertaken in healthy volunteers to determine the relation between serum levels of pepsinogen A, pepsinogen C, pepsinogen A:C ratio, and gastrin on the one hand and histology of the gastric mucosa on the other. The grade of gastritis was scored separately for antral and fundic mucosa by three different classifications: Whitehead, activity, and the Sydney score. Among 48 healthy volunteers studied, 17 were found to have gastritis according to the criteria of Whitehead. Fourteen of these 17 subjects with gastritis hadH. pylori in gastric biopsies. In all 48 subjects serum pepsinogen A (r=0.298−0.506;P〈0.01−P〈0.05), pepsinogen A:C ratio (r between −0.377 and −0.495;P〈0.001−P〈0.05) and gastrin (r=0.38−0.695;P=0.007−P〈0.01) were significantly correlated to the severity of both antral and body gastritis as assessed by all three classifications. In contrast, there was no significant correlation between serum pepsinogen C and any of the gastritis scores. When the 17 subjects with gastritis were analyzed separately, there were no correlations between the parameters studied and gastritis of the antrum. Regarding the corpus mucosa, serum PgA correlated significantly with the activity score (r=0.520;P=0.03), weakly with the Sydney score (r=0.465;P=0.06), but not with the Whitehead score. Serum PgC correlated with the Whitehead (r=0.555;P=0.02) and Sydney score (r=0.523;P=0.03), but only weakly with the activity score (r=0.441;P=0.08). The pepsinogen A:C ratio showed only a weak inverse correlation with the Whitehead gastritis score (r=−0.471;P=0.06), but not with the two other scores. Serum gastrin was significantly correlated with the Whitehead (r=0.634;P=0.006) and the Sydney score (r=0.501;P=0.04), but not with the activity score of the fundic mucosa. It is concluded that among healthy volunteers with gastritis, serological parameters are only correlated to the severity of corpus but not of antral gastritis. Serum PgC and gastrin correlated to the severity of corpus gastritis only if atrophy is comprised in the classification. In contrast, serum PgA correlates only with the activity of corpus gastritis. Thus, serological parameters reflect specific histologic features of gastritis of the gastric body, but not of the antrum.
    Type of Medium: Electronic Resource
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