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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of interventional cardiology 15 (2002), S. 0 
    ISSN: 1540-8183
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Cavities formed in ruby (99.46Al2O3·0.54Cr2O3) by the healing and annealing of indentation cracks at 1600°C are more equiaxed than similar cavities in sapphire. Surface energies for the observed facet planes (R, S, and A) relative to the surface energy of the basal plane, C, were γA/C= 1.00 ± 0.03, γR/C= 1.05 ± 0.07, and γS/C= 1.02 ± 0.04, with the uncertainty representing 95% confidence limits. Thus, the surface energies of all observed facets were statistically indistinguishable. Unlike sapphire, P-plane facets were not observed. The substantial rounding of the cavities in ruby indicated that portions of the Wulff shape were above the roughening transition temperature. Thus, even though Cr2O3 and Al2O3 form ideal solutions, Cr3+ ions are sufficiently surface active to modify the relative free energy of the surfaces.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The molecular mechanisms underlying the activity-linked plasticity of acetylcholinesterase (AChE) mRNA levels in mammalian skeletal muscle have yet to be established. Here, we demonstrate that denervation of adult muscle induces a dramatic (up to 90%) and rapid (within 24 h) decrease in the abundance of AChE mRNAs. By contrast, denervation of 14-day-old rats leads to a significantly less pronounced reduction (50% of control) in the expression of AChE mRNAs. Assessment of the transcriptional activity of the AChE gene reveals that it remains essentially unchanged in adult denervated muscles, whereas it displays an approximately two- to three-fold increase (p 〈 0.05) in denervated muscles from 2- to 14-day-old rats. In addition, we observed a higher rate of degradation of in vitro transcribed AChE mRNAs upon incubation with protein extracts from denervated muscles. Finally, UV-crosslinking experiments reveal that denervation increases the abundance of RNA-protein interactions in the 3′ untranslated region of AChE transcripts. Taken together, these data suggest that the abundance of AChE transcripts in mature muscles is controlled primarily via posttranscriptional regulatory mechanisms, whereas in neo- and postnatal muscles, both transcriptional and posttranscriptional regulation appears critical in dictating AChE mRNA levels. Accordingly, the activity-linked transcriptional regulation of the AChE gene appears to demonstrate a high level of plasticity during muscle development when maturation of the neuromuscular junctions is still occurring.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Staufen is an RNA-binding protein, first identified for its role in oogenesis and CNS development in Drosophila. Two mammalian homologs of Staufen have been identified and shown to bind double-stranded RNA and tubulin, and to function in the somatodendritic transport of mRNA in neurons. Here, we examined whether Staufen proteins are expressed in skeletal muscle in relation to the neuromuscular junction. Immunofluorescence experiments revealed that Staufen1 (Stau1) and Staufen2 (Stau2) accumulate preferentially within the postsynaptic sarcoplasm of muscle fibers as well as at newly formed ectopic synapses. Western blot analyses showed that the levels of Stau1 and Stau2 are greater in slow muscles than in fast-twitch muscles. Muscle denervation induced a significant increase in the expression of Stau1 and Stau2 in the extrasynaptic compartment of both fast and slow muscles. Consistent with these observations, we also demonstrated that expression of Stau1 and Stau2 is increased during myogenic differentiation and that treatment of myotubes with agrin and neuregulin induces a further increase in the expression of both Staufen proteins. We propose that Stau1 and Stau2 are key components of the postsynaptic apparatus in muscle, and that they contribute to the maturation and plasticity of the neuromuscular junction.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 86 (2003), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Dystonia musculorum (dt) mice suffer from a severe sensory neuropathy caused by mutations in the gene encoding the cytoskeletal cross-linker protein dystonin/bullous pemphigoid antigen 1 (Bpag1). Loss of function of dystonin/Bpag1 within neurons leads to a loss in the maintenance of cytoskeletal organization and to the development of focal axonal swellings prior to death of the neuron. In the present study, we demonstrate that neurons within the sciatic nerves of dt27J mice undergo axonal degeneration as has been previously reported for the dorsal roots. Furthermore, ultrastructural studies reveal a perturbed organization of the neurofilament and microtubule networks within the axons of sciatic nerves in dt27J mice. The disrupted cytoskeletal organization suggested that axonal transport is affected in dt mice. To address this, we assessed fast axonal transport by measuring the rate of accumulation of acetylcholinesterase (AChE) proximal and distal to a surgically introduced ligature on the sciatic nerves of normal and dt27J mice. Our findings demonstrate that axonal transport of AChE in both orthograde and retrograde directions is markedly affected, and allow us to conclude that axonal transport defects do exist in the sciatic nerves of dt27J mice.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Bingley : Emerald
    Internet research 10 (2000), S. 317-328 
    ISSN: 1066-2243
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Computer Science
    Notes: Examines the use of query reformulation, and particularly the use of relevance feedback by users of the Excite Web search engine. A total of 985 user search sessions from a data set of 18,113 user search sessions containing 51,473 queries were examined. Includes a qualitative and quantitative analysis of 191 user sessions including more than one query, to examine patterns of user query reformulation; and second, all 804 user sessions including relevance feedback were examined. Results show limited use of query reformulation and relevance feedback by Excite users - only one in five users reformulated queries. Most relevance feedback sessions were successful. Identifies the most common pattern of searching and discusses implications for Web search system design.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Bingley : Emerald
    Internet research 14 (2004), S. 19-33 
    ISSN: 1066-2243
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Computer Science
    Notes: Much previous research on improving information retrieval applications has focused on developing entirely new systems with advanced searching features. Unfortunately, most users seldom utilize these advanced features. This research explores the use of a software agent that assists the user during the search process. The agent was developed as a separate, stand-alone component to be integrated with existing information retrieval systems. The performance of an information retrieval system with the integrated agent was subjected to an evaluation with 30 test subjects. The results indicate that agents developed using both results from previous user studies and rapidly modeling user information needs can result in an improvement in precision. Implications for information retrieval system design and directions for future research are outlined.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Journal of documentation 60 (2004), S. 266-278 
    ISSN: 0022-0418
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Information Science and Librarianship
    Notes: The Web is a communication and information technology that is often used for the distribution and retrieval of personal information. Many people and organizations mount Web sites containing large amounts of information on individuals, particularly about celebrities. However, limited studies have examined how people search for information on other people, using personal names, via Web search engines. Explores the nature of personal name searching on Web search engines. The specific research questions addressed in the study are: "Do personal names form a major part of queries to Web search engines?"; "What are the characteristics of personal name Web searching?"; and "How effective is personal name Web searching?". Random samples of queries from two Web search engines were analyzed. The findings show that: personal name searching is a common but not a major part of Web searching with few people seeking information on celebrities via Web search engines; few personal name queries include double quotations or additional identifying terms; and name searches on Alta Vista included more advanced search features relative to those on AlltheWeb.com. Discusses the implications of the findings for Web searching and search engines, and further research.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of grain size on the tensile creep of silicon nitride was investigated on two materials, one containing 5% by volume Yb2O3, the other containing 5% by volume Yb2O3 and 0.5% by mass Al2O3. Annealing of the Al2O3-free silicon nitride for a longer period during processing increased the grain size by a factor of 2. This increase did not affect the tensile creep rate; the grain size exponent of the creep rate differed little from zero, p=−0.20 ± 1.37 (95% confidence level). This finding supports the more recent theories of tensile creep for which p= 0 or −1 and rejects the more classical theory of solution-precipitation. In compression, a more limited data set showed p=−1.89 ± 1.72 (95% confidence level). In contrast to the Al2O3-free material, a longer term anneal of the Al2O3-containing material during processing did not increase its grain size. Despite this, the longer-annealed Al2O3-containing material crept 10 to 100 times slower than the short-annealed material. The enhancement of creep resistance may be a consequence of SiAlON formation during the additional annealing, which reduces the Al content in the amorphous phase and increases its viscosity. Such changes in chemical composition of the grain boundaries are more effective in controlling tensile creep rate than is the grain size.
    Type of Medium: Electronic Resource
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