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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Accreditation and quality assurance 1 (1996), S. 3-13 
    ISSN: 1432-0517
    Keywords: Key words Traceability ; Mole ; Definition ; Measurements ; Chemical metrology ; Calibration ; Validation ; Reference materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  By the definition of the mole as a base unit for amount-of-substance measures within the International System of Units (SI), chemists can make chemical measurements in full compliance with established metrological principles. Since the mole requires exact knowledge of the chemical entity, which is often neither available nor of practical relevance to the purpose of the measurement, the SI units of mass or length (for volume) are unavoidable in the expression of results of many chemical measurements. Science, technology, and trade depend upon a huge and ever increasing number and variety of chemical determinations to quantify material composition and quality. Thus, international harmonization in the assessments of processes, procedures, and results is highly desirable and clearly cost effective. The authors, with relevant experience and responsibilities in Europe and America, have found some consensus in the interpretation of the metrological principles for chemical measurements, but believe open discussion should precede wide implementation by chemical communities. In fostering this dialogue, this paper shows, for instance, that more precise interpretation of the definitions for "traceability," "calibration," and "validation" is needed for present-day chemical measurements. Problems that face scientists in making measurements do not all vanish just by adherence to the SI. However, such compliance can improve communication among chemists and metrologists.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Accreditation and quality assurance 2 (1997), S. 168-179 
    ISSN: 1432-0517
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The authors propose definitions and terminology for protocols on traceability links, generally to the international system of units, for specific chemical-analytical measurements in accordance with recognized principles of science. These definitions and terms could be useful in science, technology, commerce or law. A chain of such links leads from a measurand in a sample up to a unit in the International System of Units or, if unavailable, to a value on an internationally recognized measurement scale. The quality of such a chain is quantified by combining all recognized uncertainties estimated for all its links. These uncertainties of the measured values arise from many potential error sources. The protocols should give details of specific uses of reference materials, measuring instruments and standard measurement methods.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Environmental geology 36 (1998), S. 235-258 
    ISSN: 1432-0495
    Keywords: Key words Delta lagoons ; Fish resources ; Manzala Lagoon ; Nile Delta ; Pollution ; Waste water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The Manzala Lagoon in Egypt's Nile Delta has become a sediment sink of reduced area and depth, with increased contaminant levels. Loss of much-needed fresh to brackish water reserves and decreased fish catches have serious ramifications. Herein, maps of temporal and regional sediment distributions in Manzala incorporate petrological and statistical analyses of 200 surficial and short core samples. These provide baseline information needed to help implement protection measures for this vital wetland. Four periods are considered: 1920s, 1940s, ∼1965, and 1990. Important depositional changes between 1940s and ∼1965 resulted from anthropogenic effects on this quasi-closed lagoon system, including industrial buildup, wetland conversion to agricultural land, and irrigation waterway development. Further modification from ∼1965 to 1990 is associated with closure of the Aswan High Dam, continued construction of waterways that discharge waste water into lagoon margins, and marine incursion into the northern lagoon. If current practices continue, the lagoon could be reduced to about one-third of its present area by 2050 AD.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Environmental geology 34 (1998), S. 183-193 
    ISSN: 1432-0495
    Keywords: Key words Manzala lagoon ; Nile delta ; Chernobyl ; Radionuclides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  This study was undertaken to determine whether recent anthropogenic changes in the Nile basin have affected the modern rate of sediment accumulation in the Nile delta. Excess 210Pb, 137Cs, and 239,240Pu were used to develop a sediment chronology for a core from central Manzala lagoon, the delta sector which has had the highest average rate of sediment accumulation during the Holocene (to about 0.7 cm year–1). Excess 210Pb was detected in the top 32 cm of the core, yielding an accumulation rate of 1.2 cm year–1, higher than the mean rate for the Holocene. A high 137Cs/239,240Pu ratio requires a reactor source (possibly Chernobyl) for these nuclides. Low concentrations of excess 210Pb and weapons-fallout nuclides precluded recognition of changes in sediment accumulation rate in Manzala lagoon during this century and may limit the use of tracer radionuclides for modern sediment chronology in the Nile delta.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK and Boston, USA : Blackwell Publishers Ltd
    Journal of business finance & accounting 26 (1999), S. 0 
    ISSN: 1468-5957
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: On April 26, 1982, Moody’s Investors Service refined its rating system for the first time in its seventy-three year rating history. We examine the information content of the rating refinement in the study. We find a statistically significant change in the yields on bonds whose ratings were downgraded. The detection of the impact of refinement on bond prices implies that rating agencies perform an important function in financial markets, that is they provide information to investors.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Osney Mead, Oxford OX2 0EL, UK : Blackwell Science Ltd
    Molecular microbiology 18 (1995), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The study of pathogenic is often limited to ex vivo assays and cell-culture correlates. A greater understanding of infectious diseases would be facilitated by in vivo analyses. Therefore, we have developed a method for detecting bacterial pathogens in a living host and used this method to evaluate disease processes for strains of Salmonella typhimurium that differ in their virulence for mice. Three strains of Salmonella were marked with bioluminescence through transformation with a plasmid conferring constitutive expression of bacterial luciferase. Detection of photons transmitted through tissues of animals infected with bioluminescent Salmonella allowed localization of the bacteria to specific tissues. In this manner progressive infections were distinguished from those that were persistent or abortive. We observed patterns of bio-luminescence that suggested the caecum may play a pivotal role in Salmonella pathogenesis. In vivo efficacy of an antibiotic was monitored using this optical method. This study demonstrates that the real time non-invasive analyses of pathogenic events and pharmacological monitoring can be performed in vivo.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 60 (1995), S. 767-771 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 11131-11140 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Arid and semiarid climates comprise roughly 40% of the earth’s terrestrial surface. Deserts are predicted to be extremely responsive to global change because they are stressful environments where small absolute changes in water availability or use represent large proportional changes. Water and carbon dioxide fluxes are inherently coupled in plant growth. No documented global change has been more substantial or more rapid than the increase in atmospheric CO2. Free Air CO2 Enrichment (FACE) technology permits manipulation of CO2 in intact communities without altering factors such as light intensity or quality, humidity or wind. The Nevada Desert FACE Facility (NDFF) consists of three 491 m2 plots in the Mojave Desert receiving 550 μL L–1 CO2, and six ambient plots to assess both CO2 and fan effects. The shrub community was characterized as a Larrea–Ambrosia–Lycium species complex. Data are reported through 12 months of operation.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1527-3458
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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