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  • Electronic Resource  (11)
  • 1990-1994  (5)
  • 1985-1989  (2)
  • 1980-1984  (4)
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  • Electronic Resource  (11)
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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3648-3648 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optimization of magneto-optic media for data storage applications involves a detailed consideration of the impact of material properties on the overall performance and reliability characteristics of the complete media design, which includes both the active layer structure and the substrate material. Currently, the most highly developed materials for the active layer are the amorphous rare earth-transition metal (RE-TM) alloys. The RE-TM composition determines both the Curie temperature and the compensation temperature, both of which parameters affect the sensitivity, and therefore the data rate which can be achieved using currently available diode lasers. The thermal and optical characteristics of the active layer thin-film structure affect the sensitivity, and also determine the degree of enhancement of the shot-noise-limited SNR during playback. Reliability of magneto-optic media is affected by uniform surface oxidation of RE-TM alloys, which leads to reduced Kerr rotation through the formation of an absorptive surface layer with only in-plane anisotropy. The proper choice of dielectric passivation layers and deposition process can significantly limit this and other degradation mechanisms. The choice of substrate material must be compatible with the coating process for the active layer structure, provide a stable mechanical interface to the drive mechanisms, and also possess good optical properties, most notably low birefringence. This talk will review the current directions in materials research on magneto-optic media, and relate the physical characteristics of the materials involved to the major requirements of the data storage application.
    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 57 (1985), S. 3918-3918 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: At the present time, the two major approaches to reversible optical data storage are based on either the magneto-optic effect in rare-earth–transition-metal alloys, or on the amorphous-to-crystalline phase transition in a variety of tellurium-based materials. The phase transition approach is attractive because of the relatively large optical read-signal modulation which results. However, careful optimization of these materials is required to satisfy all of the requirements of data retention, fast erasure and a high number of record/erase cycles. The data retention characteristics and cyclability of magneto-optic storage media are not considered to be critical issues. However, the inherently small magnitude of the magneto-optic effect has led, historically, to relatively limited values for playback signal to noise ratio. Antireflective thin-film structures can be used to provide enhancements to the signal to noise ratio of magneto-optic media. The underlying principles and effect of such approaches to the design of magneto-optic media will be reviewed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 297 (1982), S. 104-106 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] RESEARCH and development in the field of high-density optical data storage media and devices continue to move forward at a brisk pace - in the eighteen months since last reviewed in these columns1, several companies have committed themselves to development efforts and the introduction of commercial ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Educational studies in mathematics 24 (1993), S. 1-4 
    ISSN: 1573-0816
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Educational studies in mathematics 24 (1993), S. 115-137 
    ISSN: 1573-0816
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Three teaching experiments are reported which study aspects of a diagnostic teaching methodology based on identifying key conceptual points and misconceptions, focusing on these, giving substantial open challenges, provoking cognitive conflict, and resolving it through intensive discussion. An experiment in the field of directional quantities showed a positive relation between the intensity of discussion and amount of learning; one on fractions and another on geometric reflections both showed — in comparison with individualized booklets, for which retention was very low — strikingly good two-month retention under the experimental teaching methods. The particular misconceptions found in each topic are also described.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Behavior genetics 23 (1993), S. 313-322 
    ISSN: 1573-3297
    Keywords: Homosexuality ; sexual orientation ; familiality ; environment ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract We examined data from a large cohort of homosexual and heterosexual females and males concerning their siblings' sexual orientations. As in previous studies, both male and female homosexuality were familial. Homosexual females had an excess of homosexual brothers compared to heteroxual subjects, thus providing evidence that similar familial factors influence both male and female homosexuality. Furthermore, despite the large sample size, homosexual females and males did not differ significantly from each other in their proportions of either homosexual sisters or homosexual brothers. Thus, results were most consistent with the possibility that similar familial factors influence male and female sexual orientation. However, because results conflicted with those of some other studies, and because siblings' sexual orientations were obtained in a manner likely to yield more errors than in these other, smaller studies, further work is needed using large samples and more careful methods before the degree of cofamiliality of male and female homosexuality can be resolved definitively. We also examined whether some parental influences comprised shared environmental effects on sexual orientation. Scales attempting to measure such influences failed to distinguish subjects with homosexual siblings from subjects with only heterosexual siblings and, thus, did not appear to measure shared environmental determinants of sexual orientation.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Educational studies in mathematics 12 (1981), S. 399-420 
    ISSN: 1573-0816
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This article examines the conceptual problems that children experience when attempting to solve verbal problems which contain decimal numbers. After discussing the existing research, we then describe an experiment that was designed in three phases: 1. Exploratory interviews to discover existing conceptions and difficulties and to discover how pupils made use of diagrams, simpler numbers, and strategies. These interviews exposed difficulties with the understanding of place value, the effect of multiplying and dividing by a positive number less than one, the symbolisms of division and its noncommutative nature, the units associated with the numbers and also with familiar names for the operations. The three strategies were all found to be unfamiliar to pupils and their difficulties are discussed. 2. The design and administration of a diagnostic test, based on the results of these interviews, to a class of less able 14 year olds. 3. The preparation and use of calculator enriched teaching materials designed to remedy the identified misconceptions. From the pre- and post-test results we note the dramatic success of the teaching in improving pupils' understanding of place value, although there is a more modest improvement in enabling pupils to choose the correct operation by drawing diagrams, using easier numbers and estimating.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Educational studies in mathematics 24 (1993), S. 5-34 
    ISSN: 1573-0816
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this introductory article, after some initial discussion of an appropriate approach to mathematics as a curriculum subject, we sketch a theory for designing teaching, based on mathematical activity, situations, tasks, and interventions, exposing and resolving cognitive conflicts, changes of structure and context, feedback, reflection and review. We next review the main psychological principles underlying this theory, then consider some examples of teaching designs in the light of the theory. Thus we open the discussion of the theme of this issue, which continues with the fuller discussion of other examples in the remaining articles.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Educational studies in mathematics 15 (1984), S. 129-147 
    ISSN: 1573-0816
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract 12-and 13-year-olds were tested with two types of tasks to test their understanding of applications of the multiplication and division of positive numbers: (i) writing down calculations required to solve verbal problems, and (ii) making up stories to fit given calculations. Selected pupils were interviewed to investigate further the thinking processes involved. The results indicate (a) the pervasive nature of certain numerical misconceptions, (b) the effects of structural differences among the items; particularly whether multiplication can be conceived as repeated addition or not, and whether division has the structure of partition, quotition or rate, (c) specific effects of context attributable to such aspects as relative familiarity, and (d) various interactions between these three sets of factors.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Archives of sexual behavior 23 (1994), S. 475-486 
    ISSN: 1573-2800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Psychology
    Type of Medium: Electronic Resource
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