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Quantitative Basis (quantitative + basis)
Selected AbstractsThe Relationship of Cycloaddition Reactions to Spontaneous Vinyl PolymerizationsHELVETICA CHIMICA ACTA, Issue 6 2005Henry The zwitterionic,biradical tetramethylene proposed by Huisgen as the key intermediate in stepwise [2+2] cycloaddition reactions has been shown to be the crucial intermediate in spontaneous vinyl polymerizations as well. Predominantly biradical tetramethylenes initiate free-radical copolymerizations, while predominantly zwitterionic tetramethylenes initiate cationic or anionic homopolymerizations. Stepwise cycloaddition is viewed as a spontaneous polymerization lacking a propagation step. These tendencies could be correlated in the form of an ,organic chemist's Periodic Table', which has recently been put on a quantitative basis. Huisgen also showed experimentally that [4+2] Woodward,Hoffman -allowed cycloadditions are completely concerted. Spontaneous copolymerizations accompanying these cycloadditions, therefore, were ascribed to the s- trans diene form. This concept was given support by kinetics studies, as well as by exclusive cycloaddition from s- cis cyclopentadiene, and exclusive copolymerization from s- trans verbenene. [source] Space-group determination from powder diffraction data: a probabilistic approachJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2004Angela Altomare Experimental powder diffraction diagrams, once indexed and decomposed into single diffraction intensities, can be submitted to statistical analysis for the determination of space-group symmetry. A new algorithm is illustrated, which is able to provide, on a quantitative basis, a probability value for each extinction symbol compatible with the previously established lattice symmetry. The algorithm has been implemented in EXPO2004 [Altomare, Caliandro, Camalli, Cuocci, Giacovazzo, Moliterni & Rizzi (2004). J. Appl. Cryst.37, 1025,1028] and has been successfully tested using a large set of experimental data. [source] Population-based research on occupational and environmental factors for leukemia and non-Hodgkin's lymphoma: The Northern Germany Leukemia and Lymphoma Study (NLL),AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 4 2008W. Hoffmann MPH Abstract Background The Northern Germany Leukemia and Lymphoma Study (NLL) is a population-based study designed to provide a quantitative basis for investigations into occupational and environmental risk factors for leukemia and lymphoma. Methods All incident cases of leukemia and lymphoma diagnosed between 1/1/1986 and 12/31/1998 in six counties in Northern Germany were actively ascertained. Controls were selected from population registries. Use of pesticides, sources of food supply, time spent at home and work, medical and family history were assessed via face-to-face interview. This self-reported information was used in conjunction with direct environmental measurements of pesticides in household dust and electromagnetic fields (EMFs). In addition, geographical information system (GIS) data were used to derive estimates of environmental exposure to pesticides, EMFs associated with transmission lines, and ionizing radiation from routine nuclear power reactor operations. Occupational exposure assessment was based on lifetime work history. For each job, information on branch of industry, company, job description, and duration of employment were ascertained. Results Fourteen hundred thirty cases and 3041 controls were recruited. Lifetime residential and workplace histories totaled 49,628 addresses. Occupational exposure to pesticides was reported by 15% of the male participants (women: 16%). Four percent of the men (women: 8%) were occupationally exposed to ionizing radiation for ,1 year over their lifetime. Sixty four percent of the participants had lived in the vicinity (20 km) of a nuclear power plant in operation. Conclusions The NLL illustrates the successful application of innovative methods to simultaneously assess occupational and environmental risk factors for leukemia and lymphoma including radiological hazards, pesticides, and EMFs. Am. J. Ind. Med. 51:246,257, 2008. © 2008 Wiley-Liss, Inc. [source] Überwachung und Analyse der Lebensdauer von TunnelbauwerkenBETON- UND STAHLBETONBAU, Issue 1 2007Konrad Bergmeister Prof. Dipl.-Ing. Im Tunnelbau bildet die Überwachung der signifikanten Einwirkungs- und Strukturparameter während der Bauphase und des Betriebs die Basis für die Bewertung des Zustands und der Sicherheit des Bauwerks. Die erfassten Daten stellen des Weiteren die Grundlage zur nummerischen und mechanischen Modellbildung dar, um eine effiziente Entscheidungsfindung und Maßnahmenplanung zu gewährleisten. Die Überwachung beinhaltet die Erfassung und Bewertung der geologischen Gegebenheiten, der induzierten Auswirkungen während des Vortriebs und die kontinuierliche Kontrolle für den weiteren Betrieb und Unterhalt des Bauwerks. Methoden der Bauwerksüberwachung und Diagnose stellen aufgrund der quantitativ erfassten Systemparameter ein wesentliches Element für die Zuverlässigkeitsanalyse dar. Die geeignete Wahl von Kontroll- und Messinstrumenten ist jedoch nur einen Teilaspekt der Bauwerksüberwachung. Die Auswertung und Interpretation der erhobenen Daten, die Gegenüberstellung mit den normativen Anforderungen und Grenzwerten, die Anpassung der analytischen Modellannahmen aufgrund des Vergleichs von gemessenen und berechneten Daten zeigen die Komplexität dieses Aufgabengebietes. Monitoring and Analysis of Durability of Tunnels Monitoring continuously the decisive parameters, during both the construction and the operation phase, provides the quantitative basis for safety and condition assessment, analytical modelling and decision making. This includes evaluating the conditions and induced effects during excavation and construction, and continues during operation in terms of maintenance decision making and reliability assessment. The utilisation of monitoring devices and measurement elements is however only the start of monitoring field performance. Interpretation of the acquired data is equally important, namely the validation of compliance with normative specifications and the comparison of measured and calculated data in order to evaluate analytical model assumptions. [source] Development of Auxotrophic Agrobacterium tumefaciens for Gene Transfer in Plant Tissue CultureBIOTECHNOLOGY PROGRESS, Issue 3 2004Jason I. Collens Auxotrophic strains of Agrobacterium tumefaciens were generated for use in liquid co-culture with plant tissue for transient gene expression. Twenty-one auxotrophs were recovered from 1,900 tetracycline-resistant insertional mutants generated with a suicide vector transposon mutagenesis system. Twelve of these auxotrophs were characterized on a nutrient matrix. Isolates were screened for growth in plant cell and root culture, and three auxotrophs were identified that had limited growth: adenine (ade-24), leucine (leu-27), and cysteine (cys-32). Ade-24 displayed poor T-DNA delivery in a transient expression test delivering GUS from a binary vector, while cys-32 displayed the best ability to deliver DNA of these three auxotrophs. The growth yield of cys-32 on cysteine was assessed to provide a quantitative basis for co-culture nutrient supplementation. The utility of cys-32 for delivering T-DNA to plant tissues is demonstrated, where an 85-fold enhancement in GUS expression over wild-type A. tumefacienswas achieved. [source] | ||||||||||