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  • 1
    ISSN: 1573-4846
    Keywords: GDLC ; sol-gel ; gel-glass ; electrooptical ; liquid crystal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Liquid crystal microdroplets can be trapped into silica gel-glasses by sol-gel processes. Several silica matrices containing different non-reacting organic radicals have been employed for preparing gel-glass dispersed liquid crystals (GDLC). The optical properties of thin GDLC layers may be modified by coating the material with transparent electrodes and applying external AC-voltage signals. Switching between opaque and transparent states is achieved. The sample transmission depends on the scattering properties of the material; no polarizers are required. The transmission of the transparent state is improved by matching the refractive indices of the gel-glass matrix and the liquid crystal. This can be achieved by adding high refractive index dopants to the starting mixture, or by substituting the non-reacting organic group of the silica matrix. Both approaches have been tested. Phenyl and methyl monomers have been used as well as titanium-based dopants. The resulting GDLC materials have been optimized by controlling the starting mixture composition, the reaction conditions, and the film preparation. The optics, dynamics, and stability of GDLC films are analyzed.
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  • 2
    ISSN: 1573-5044
    Keywords: daylength ; in vitro ; microtuber ; photoperiod ; potato ; secondary tuber ; Solanum tuberosum ; stolons ; tissue culture ; tuberization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Single-node cuttings of potato cultivars ‘Jemseg’, ‘Katahdin’, ‘Russet Burbank’ and ‘Superior’ were cultured on a multiplication medium containing MS salts and no growth regulators. Cultures were exposed to 8 h (SD) and 16 h (LD) photoperiodic regimes. The subsequent plantlets were excised and single node cuttings from each photoperiodic regime were placed under SD or LD on a second medium containing growth regulators which promoted tuberization. Production of microtubers was strongly influenced by genotype and by photoperiodic treatments. ‘Superior’ produced stunted plantlets and some microtubers under SD conditions in the multiplication medium. The number of microtubers formed by ‘Jemseg’ was not influenced by photoperiod. However, ‘Katahdin’ and ‘Russet Burbank’ formed fewer microtubers under LD-LD conditions compared to LD-SD, SD-SD and SD-LD regimes. Compared with the other regimes, LD-SD photoperiod generally promoted microtuber formation with larger diameters and significantly (p〈0.05) greater fresh weight. The intensity of the tuberization stimulus was affected by daylength, and this was characterized by microtubers with secondary tubers, the growth of more than one axillary microtuber, and microtubers subtended by stolons. The maturity group of the potato cultivars and photoperiodic regime in vitro strongly influenced the production of microtubers. These results can be employed to adapt light regimes for multiplication and tuberization to the specific requirements for cultivars from different maturity groups, and thus increase the efficiency of potato multiplication protocols.
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  • 3
    ISSN: 1573-6784
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An optimized procedure has been developed for production andpurification of the human interferon a receptor (IFNAR) expressed inE. coli as fusion protein with glutathione S-transferase (GST).Expression induced at 30° cell disruption performed at pH = 9.0in presence of detergents reduced the inclusion body formation andgenerated up to 20% of the fusion protein in the soluble form. Therecombinant IFNAR, recovered in soluble andrenaturated forms, wasable to block the antiviral and antiproliferative activities of IFNaB.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Space science reviews 85 (1998), S. 523-545 
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The discovery of Comet Shoemaker-Levy 9 in March 1993 opened an extraordinary few years in the study of the history of impacts in the solar system. This review paper offers a background that attempts to set the events of 1993 and 1994 into a historical context, and describes events leading to the discovery and the mounting of a unique and unprecedented international effort to observe the comet's collision with Jupiter. A selection of the results is presented to explore how the fate of Comet Shoemaker-Levy 9 has affected scientific and popular understanding of impacts in the solar system.
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  • 5
    ISSN: 1572-9931
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The species specificity of interferons (IFNs) depends on restricted recognition of these ligands by multisubunit cell surface receptors. Expression of the human receptor subunit IFNAR in mouse cells conferred sensitivity only to one subtype of human IFN, IFN-αB. Other genes on human chromosome 21 were required for responses to other subtypes of type I IFN. In contrast, IFNAR expression in hamster cells did not confer sensitivity to any human IFN tested, including IFN-αB. Using human-hamster somatic cell hybrids, we mapped theIfnabr gene, encoding a ligand-binding subunit of the IFN-α/β (type I) receptor, to human chromosome 21.Ifnabr colocalized withIfnar to the distal region of q22.1. The presence of a chromosomal fragment encoding IFNABR and IFNAR was also not sufficient to confer sensitivity to human IFN. In contrast, hybrids carrying in addition the region 21q22.2 showed a full response to human IFN-αB, suggesting that a gene located in this region encodes a third factor required for type I IFN receptor activity.
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  • 6
    ISSN: 1619-1560
    Keywords: Pupillometry ; Diabetic neuropathy ; Autonomic neuropathy ; Sensory thresholds ; Sweat function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The relationship between dynamic pupillary function and peripheral nerve function was studied in 85 randomlyselected diabetic patients and 67 age-matched normals using a portable infrared pupillometer (Pupilscan Version 5). Seven measurements were chosen to represent different components of the pupillary constriction-redilatation curve after a standardized light stimulus. Constriction latency was significantly prolonged in diabetic patients (p = 0.05), as was time to 63% redilatation (p = 0.001). Thermal thresholds at the feet weakly correlated with relative reflex amplitude (warm:r = −0.22,p = 0.05; cool:r = −0.23,p = 0.05), but vibration perception thresholds were more strongly associated with constriction and redilatation velocity (r = −0.42,p = 0.001;r = −0.28,p = 0.03). Among the cardiovascular autonomic function tests, only respiratory R—R variation correlated with constriction velocity (r = 0.47,p 〈 0.001), and Valsalva ratio with redilatation velocity (r = 0.25,p = 0.04), but postural systolic blood pressure change was also correlated with reflex amplitude and latency time (r = −0.42,p 〈 0.001;r = 0.41,p = 0.001). There were no significant associations with three measures of sweating function in the feet. Pupil measurements were abnormal in 4–11% of diabetic patients, while other neurological tests were abnormal in 8–35%, consistent with the length-dependence of diabetic neuropathy. Median coefficients of variation were 2.0–7.2% in diabetic patients. Portable pupillometry using this device is currently the simplest method available for measuring a cranial autonomic pathway, though the measurements obtained with it are only weakly associated with the results of other tests of somatic and autonomic function in diabetes, and are unrelated to measurements of distal sudomotor function.
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  • 7
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Prominent and persistent cyclic fluctuations in the abundance of consecutive year-classes occur in some sockeye salmon populations throughout the species' range. We review and test a number of explanations for the existence of these cycles using qualitative biological arguments, including a consideration of the synchrony of cycles among populations. Most of the hypotheses involve mechanisms that would reinforce synchronous population fluctuations within watersheds. However, the 4-year cycles characteristic of many Fraser River sockeye populations are sometimes out of phase with each other, both among populations which migrate together as mixed stocks while vulnerable to commerical fisheries, and among populations whose juveniles share the same nursery lake habitat (Shuswap Lake). Such asynchrony suggests that the mechanism(s) causing population cycles can operate independently within reproductively isolated populations. Of the mechanisms reviewed here, only those involving genetic effects on age at maturation, or on resistance to disease or parasites, or those involving depensatory predation soon after fry emergence, appear to offer satisfactory explanations.
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  • 8
    ISSN: 1432-2161
    Keywords: Subungual keratoacanthoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The subungual keratoacanthoma is a benign neoplasm which simulates and must be differentiated from squamous cell carcinoma. Subungual keratoacanthomas are rapidly growing tumors, causing bone destruction which usually heal spontaneously. The lesion most often presents as a painful, enlarging mass in middle-aged Caucasian patients. Radiographic examination demonstrates a lytic cup-shaped erosion of the underlying distal phalanx. It is essential to recognize keratoacanthoma and separate it from squamous cell carcinoma, both for prognostic and therapeutic reasons. We present two cases of proven subungual keratoacanthoma and discuss their radiographic and histologic characteristics, as well as the current treatment alternatives for this entity.
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  • 9
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 366 (1993), S. 583-585 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Interferon-dependent tyrosine phosphorylation of Jakl and Jak2 was examined in mouse 3T3 cells treated for various times with IFN-a or IFN-/ (Fig. la). IFN-/ stimulation resulted in time-dependent tyrosine phosphorylation of Jak2, with peak IFNa Jak2 Jak2 Jakl Blot Ab: Jakl ...
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