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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4365-4375 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A technique for the heteroepitaxy of GaAs/Si films having reduced threading dislocation density is presented. The important attribute of this technique is the suppression of three-dimensional Volmer–Weber island formation during initial deposition. This suppression is achieved by deposition of a stoichiometric GaAs buffer layer by a migration-enhanced epitaxy technique on silicon at 348 K to a thickness greater than the "monolithic thickness," hm. Subsequent GaAs films deposited by conventional molecular beam epitaxy on buffer layers of thickness greater than hm possess structural and optical characteristics that exceed those for state-of-the-art GaAs/Si layers: an x-ray full width at half maximum (FWHM) of 110 arcsec with a dislocation density at the film surface of 3×106 cm−2 and a concomitant 4 K photoluminescence FWHM of 2.1 meV. The p-i-n structures suitable for use as light-emitting diodes (LEDs) that were grown on the reduced threading dislocation density GaAs/Si and by means of forward- and reverse-bias measurements, demonstrated an ideality factor of n=1.5, an increased reverse-bias breakdown electric field of 2.1×107 V/m, and an intrinsic region resistivity of 4×107 Ω cm for LEDs of increasingly smaller mesa size. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The anisotropy ratios (parallel to the c axis versus perpendicular to the c axis) for the electrical resistivity, Seebeck coefficient, and thermal conductivity of horizontal Bridgman-grown n-type (Bi2Te3)90 (Sb2Te3)5 (Sb2Se3)5 and p-type (Sb2Te3)72 (Bi2Te3)25 (Sb2Se3)3 were measured at 300 K. The orientation having the largest thermoelectric figure of merit was perpendicular to the zone axis of the c planes (along the natural growth direction). For the n-type alloy, the maximum thermoelectric figure of merit was determined to be 3.2×10−3/K. For the p-type alloy, the maximum thermoelectric figure of merit was determined to be 3.6×10−3/K when compensated with tellurium only, and 3.8×10−3/K when compensated with both tellurium and iodine. These values represent a significant increase over previously reported p-type thermoelectric figure of merit values. Hall coefficient data coupled with Seebeck coefficient measurements suggest a difference in carrier transport phenomena caused by an increased compensation of holes in the p-type alloy without the deleterious precipitation of the tellurium-rich second phase. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 107 (2000), S. 0 
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To determine whether routine testing for serum Chlamydia trachomatis antibodies, considered in combination with a woman's clinical features, may avoid the need for diagnostic laparoscopy in routine investigation for infertility.Design Retrospective case notes analysis.Setting Secondary level care infertility clinic.Population Eighty women who had undergone both laparoscopy and serum Chlamydia trachomatis antibody testing.Methods Ascertainment of any history of suspected pelvic inflammatory disease, pelvic pain, cervical intraepithelial neoplasia, pelvic surgery or appendicectomy; any abnormality on clinical pelvic examination; the findings at laparoscopy; the result of serum Chlamydia trachomatis antibody testing by enzyme-linked immunosorbent assay (ELISA) screening with microimmunofluorescence (MIF) confirmatory diagnostic testing. The usefulness of clinical features, the serum Chlamydia trachomatis antibody test and these two variables combined in the detection of tubal disease and pelvic pathology of relevance to infertility were measured statistically.Main outcome measures Specificity, sensitivity, positive predictive value, negative predictive value and likelihood ratio for each of the tests.Results The combination of any positive clinical feature with a positive test for serum Chlamydia trachomatis antibodies detects tubal disease with sensitivity 92%, specificity 70%, positive predictive value 72%, negative predictive value 91% and likelihood ratio 3.1; it detects bilateral tubal obstruction with sensitivity 84%, specificity 51%, positive predictive value 35%, negative predictive value 91% and likelihood ratio 1.7; it detects pelvic pathology relevant to infertility with sensitivity 76%, specificity 71%, positive predictive value 80%, negative predictive value 65% and likelihood ratio 2.6. The negative predictive value for pelvic pathology from the use of clinical features in addition to the chlamydia antibody test is not significantly higher than that from the chlamydia antibody test alone (53%).Conclusions A policy of selective laparoscopy in routine investigation for infertility, based on the result of the test for serum Chlamydia trachomatis antibodies and a woman's clinical features, is not supported.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of business finance & accounting 2 (1975), S. 0 
    ISSN: 1468-5957
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    British journal of political science 10 (1980), S. 515-521 
    ISSN: 0007-1234
    Source: Cambridge Journals Digital Archives
    Topics: Political Science
    Notes: This paper describes an empirical procedure for analysing the difference between the proportion of votes a major party attracts and the proportion of seats it subsequently wins in a plurality election. This difference will be referred to as the electoral bias with respect to that particular party at the election being analysed:B = S — V, (1)where S is the seat proportion and V the vote proportion gained by the party. This bias is the basic concept underlying much of the debate about electoral reform but curiously it has been an under-researched topic in political science literature. Apart from a small continuing debate over the cubic law of seat proportions and some analyses of Australian and New Zealand elections most attention in election studies has been concerned with determining the proportion of votes rather than the subsequent proportion of seats.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 171 (1953), S. 37-38 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] These difficulties can be overcome by slowly injecting a suspension of the particles into a faster stream of fluid flowing in the same direction. Provided there is no turbulence, the wide column of particles will then be accelerated to form a narrow column surrounded by fluid of the same refractive ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Community dentistry and oral epidemiology 8 (1980), S. 0 
    ISSN: 1600-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Reorganisation of dental services in Britain gives new opportunities for planning. Geographical methodology provides new techniques. An elementary spatial analysis of variations in dental health in Newcastle Area Health Authority (Teaching) shows that dental health varies with availability and access to treatment facilities. Opposite types of geographical distribution of community (School) and general dental services are illustrated showing location biases for each type of service. The evaluation of the spatial distribution of dental services is shown to be basic to planning and a key to improved dental health.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 541 (1988), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 9
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    London : Periodicals Archive Online (PAO)
    Community development journal. 5:4 (1954:Sept.) 79 
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  • 10
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 211 (1966), S. 626-626 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In many applications it would be useful to be able to count calcium-45 directly in larger volumes of aqueous solutions without quenching corrections, even if at low efficiency. An apparatus designed for this purpose which has proved useful in this laboratory is shown in Fig. 1. It consists of an ...
    Type of Medium: Electronic Resource
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