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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3381-3385 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The low frequency noise properties of organic thin film transistors are studied here as a function of frequency and bias. Various n-channel and p-channel devices were evaluated and found to exhibit 1/f-type of noise in the 1 Hz–10 kHz range. The drain current noise is found to vary proportionally with drain current. The noise level is comparable to that found in Si metal–oxide–semiconductor field-effect transistors within the operation region of the devices, owing to the smaller drain currents in organic transistors, although the intrinsic noise is considerably higher in the organic transistors. The viability of using the organic materials in low noise circuits is demonstrated by a ring oscillator. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 435-445 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method is presented for the analysis of magnetic force microscopy (MFM) measurements that allows the quantitative determination of the sample stray field. It is shown how measurements on an easily obtainable calibration sample can be used to calibrate the MFM measurement as a function of the wavelength of the sample stray field at the tip apex. It is demonstrated that the thus obtained MFM calibration can be used to determine the stray field distribution of the tip. Furthermore, the effect of the tip on the MFM imaging mechanism is analyzed by comparing it to some simple tip models. From the analysis, it is shown that the point–monopole and dipole models do not accurately describe the MFM imaging mechanism. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 23 (2000), S. 649-711 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Changing the strength of connections between neurons is widely assumed to be the mechanism by which memory traces are encoded and stored in the central nervous system. In its most general form, the synaptic plasticity and memory hypothesis states that "activity-dependent synaptic plasticity is induced at appropriate synapses during memory formation and is both necessary and sufficient for the information storage underlying the type of memory mediated by the brain area in which that plasticity is observed." We outline a set of criteria by which this hypothesis can be judged and describe a range of experimental strategies used to investigate it. We review both classical and newly discovered properties of synaptic plasticity and stress the importance of the neural architecture and synaptic learning rules of the network in which it is embedded. The greater part of the article focuses on types of memory mediated by the hippocampus, amygdala, and cortex. We conclude that a wealth of data supports the notion that synaptic plasticity is necessary for learning and memory, but that little data currently supports the notion of sufficiency.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: In order to develop a microsatellite typing system for Lepeophtheirus salmonis (Krøyer), a DNA preparation method for individual sea lice suitable for analysis by polymerase chain reaction (PCR) was designed, and the DNA sequences of 50 L. salmonis microsatellite elements were determined. The microsatellites were composed of 60% perfect, 25% imperfect, and 15% compound repeats. Based on the flanking DNA sequences, four microsatellite-PCR assays were optimized and used in a pilot study to analyse L. salmonis samples collected in Ireland, Norway and Scotland. Two of the microsatellite-PCR assays targeted polymorphic loci amplifying seven and 10 alleles respectively. The results showed that microsatellite-PCR typing could detect genetic variation both within and between the L. salmonis groups, and also was capable of amplifying group-specific alleles.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The paradigm for differential antigen expression in Borrelia burgdorferi, the agent of Lyme disease, is the reciprocal expression of its outer surface (lipo)proteins (Osp) A and C; as B. burgdorferi transitions from its arthropod vector into mammalian tissue, ospC is upregulated, and ospA is downregulated. In the current study, using B. burgdorferi cultivated under varying conditions in BSK-H medium, we found that a decrease in pH, in conjunction with increases in temperature (e.g. 34°C or 37°C) and cell density, acted interdependently for the reciprocal expression of ospC and ospA. The lower pH (6.8), which induced the reciprocal expression of ospC and ospA in BSK-H medium, correlated with a drop in pH from 7.4 to 6.8 of tick midgut contents during tick feeding. In addition to ospC and ospA, other genes were found to be regulated in reciprocal fashion. Such genes were either ospC-like (e.g. ospF, mlp-8 and rpoS) (group I) or ospA-like (lp6.6 and p22) (group II); changes in expression occurred at the mRNA level. That the expression of rpoS, encoding a putative stress-related alternative sigma factor (σs), was ospC-like suggested that the expression of some of the group I genes may be controlled through σs. The combined results prompt a model that allows for predicting the regulation of other B. burgdorferi genes that may be involved in spirochaete transmission, virulence or mammalian host immune responses.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Pty
    Australasian journal of dermatology 41 (2000), S. 0 
    ISSN: 1440-0960
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: There are limited reports of the prevalence of positive reactions in healthy adults to patch tests with standard allergens; there are no recent comprehensive studies from Australia. Healthy adult volunteers (n = 219) from the Western Australian community were patch tested using the European standard series of allergens. Seventy-seven (35%) reacted to at least one allergen, positive patch tests being most prevalent to nickel sulfate (20%), potassium dichromate (9%), cobalt chloride (6%) and fragrance mix (4%). Prevalence of positive patch tests to nickel and chromate was higher than that reported for another healthy population, which may stem from self-selection of volunteers or geographical differences, including extent of exposure to allergens.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 406 (2000), S. 681-682 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Attempted solutions to the problems caused by modern agriculture, such as the overuse of fertilizers and pesticides, are usually expensive and often lead to new problems. But this need not be so, as Zhu and colleagues show on page 718 of this issue. By growing a simple mixture of rice ...
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1534-4681
    Keywords: Gastric cancer ; Familial screening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: This investigation was undertaken to define the demographic, clinicopathological, and prognostic factors relevant to young patients with gastric adenocarcinoma. Methods: A prospective database of all patients with gastric cancer who presented to Memorial Sloan-Kettering Cancer Center was started in 1985. Clinical, pathological, and operative records and follow-up data on 92 patients, 40 years of age or younger, with a primary diagnosis of gastric cancer were reviewed. Results: The mean patient age was 35 6 4.9 years (range, 17–40 years), and 52 were male. The male-to-female ratio of patients younger than 30 was 0.85/1; whereas in those older than 30, the ratio was 1.45/1. Sixty-six percent of the patients were white, 15% Asian, 11% Hispanic, and 8% were black American. Nineteen percent of patients reported a family history of gastric cancer. Sixty-six patients (71%) presented with stage III or IV disease, whereas 13 patients, each, presented with stage I or II disease. Poorly differentiated lesions were present in 71%. Resection with curative intent was undertaken in 47 patients, and resection with palliative intent was performed in 24 patients. Tumor site (proximal vs. distal vs. linitus plastica), advanced T stage, and the presence of nodal disease were significant predictors of disease-free survival on both univariate and multivariate analyses. The mean survival time and disease-specific 5-year survival rates for individual Union International Contre le Cancer tumor stages were similar to those observed in older populations of patients with gastric cancer; and eight patients, who presented with early (T1/T2) node-negative tumors, are alive and well a minimum of 60 months after resection. Conclusions: The high frequency of a positive family history in young patients suggests an opportunity to identify a high-risk population for screening.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 338-342 (May 2000), p. 889-892 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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