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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 5756-5777 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dissociation of CH4 physisorbed on Ni(111) at 46 K is observed to be induced by the impact of incident inert gas atoms. The dynamics and mechanism of this new process, collision induced dissociative chemisorption, are studied by molecular beam techniques coupled with ultrahigh vacuum electron spectroscopies. The absolute cross section for collision induced dissociation is measured over a wide range of kinetic energies (28–109 kcal/mol) and incident angles of Ne, Ar, and Kr atom beams. The cross section displays a complex dependence on the energy of the impinging inert gas atom characteristic of neither total nor normal energy scaling. Quantitative reproduction of the complex dependence of the cross section on the Ar and Ne incident energy by a two-step, dynamical model establishes the mechanism for collision induced dissociation. Collision induced dissociation occurs by the impulsive transfer of kinetic energy upon collision of Ar or Ne with CH4, followed by the translationally activated dissociative chemisorption of the CH4 upon its subsequent collision with the Ni surface. The dependence of the probability of activated dissociation on the resultant CH4 normal energy derived from the fit of the model to the experimental cross section is in excellent agreement with the results of a previous study of the translationally activated dissociative chemisorption of CH4 on Ni(111). Collision induced activation and translational activation are shown to be consistent mechanisms for providing energy to CH4 to surmount the barrier to dissociative chemisorption.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 16 (1989), S. 0 
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Kaposi's sarcoma is associated with an increased frequency of HLA-DR5. The hypothesized model of a susceptibility gene in linkage disequilibrium with DR5 may be tested by haplotype analysis in familial Kaposi's sarcoma. Our finding of no common haplotype among afflicted members of a family provides evidence against the hypothesized linkage.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Child 22 (1996), S. 0 
    ISSN: 1365-2214
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Summary This study was set up to compare the frequency of health, educational and behavioural problems in a geographically defined birth cohort of 7-year-old children grouped by weight at birth. The study design was based on a multi-stage postal survey, with sampling stratified by birthweight. It took place in the four counties of Oxfordshire, Buckinghamshire, Berkshire and Northamptonshire which make up the former Oxford region. We studied 1319 live births to women resident in the former Oxford region in1985, including all those with birthweights under 1500 g, or whose weight was not recorded, and a sample of those who weighed 1500–2499 g, and of those who weighed 2500 g or more at birth. The children in the sample were traced through the National Health Service Central Register (NHSCR) and self-administered questionnaires were sent to their parents, general practitioners (GP) and teachers. Of the 1169 children who were alive at the age of 7 years and were successfully traced, 805 (75%) were followed up by postal survey. The use of health services, and of additional educational support was higher, and school performance was poorer among children who had weighed less than 1500 g at birth than among children who had weighed 2500 g or more, with the rates for children who had weighed 1500–2499 g falling in between. This survey method identifies the higher rate of health and educational problems in children weighing under 2500 g at birth, particularly those with birthweight under 1500 g, compared with other children. The method could be developed to provide a way of monitoring any changes over time in the prevalence of these problems. This information can be used to assess the health and educational needs of 7-year-old children in the population.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 111 (1989), S. 8748-8749 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Landscape ecology 3 (1989), S. 193-205 
    ISSN: 1572-9761
    Keywords: hierarchy theory ; nonequilibrium ; thermodynamics ; catastrophe theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Landscapes are complex ecological systems that operate over broad spatiotemporal scales. Hierarchy theory conceptualizes such systems as composed of relatively isolated levels, each operating at a distinct time and space scale. This paper explores some basic properties of scaled systems with a view toward taking advantage of the scaled structure in predicting system dynamics. Three basic properties are explored: (1) hierarchical structuring, (2) disequilibrium, and (3) metastability. These three properties lead to three conclusions about complex ecological systems. First, predictions about landscape dynamics can often be based on constraints that directly result from scaled structure. Biotic potential and environmental limits form a constraint envelope, analogous to a niche hypervolume, within which the landscape system must operate. Second, within the constraint envelope, thermodynamic and other limiting factors may produce attractors toward which individual landscapes will tend to move. Third, because of changes in biotic potential and environmental conditions, both the constraint envelope and the local attractors change through time. Changes in the constraint structure may involve critical thresholds that result in radical changes in the state of the system. An attempt is made to define measurements to predict whether a specific landscape is approaching a critical threshold.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 45 (1989), S. 1114-1115 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0428
    Keywords: Non-insulin-dependent diabetes mellitus ; low density lipoprotein oxidation ; low density lipoprotein fatty acids ; lipid peroxidation ; conjugated dienes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Oxidation of low density lipoprotein (LDL) plays an important role in the pathogenesis of atherosclerosis and is related to the fatty acid composition which is altered in diabetes mellitus. This study examines the relationship between the fatty acid composition of LDL and high density lipoprotein (HDL) and lipoprotein oxidation. A group of nine non-insulin-dependent diabetic (NIDDM) patients were compared to seven healthy control subjects before and after a high monounsaturated diet. Lipoproteins were isolated and oxidisability was measured by conjugated diene formation and lipid peroxide analysis. Serum HDL cholesterol was significantly lower in the diabetic patients. LDL cholesteryl ester linoleic acid in the diabetic patients was significantly higher at baseline and decreased after diet (p〈0.05) while oleic acid increased in both diabetic and non-diabetic subjects (p〈0.05). HDL cholesteryl ester oleic acid was lower in the diabetic patients compared with control subjects (p〈0.05) before diet and it increased significantly after diet (p〈0.05). LDL lipid peroxides and conjugated diene formation were related to LDL glycation (r=0.46, p〈0.05 and r=0.49, p〈0.05, respectively). Both decreased following diet (lipid peroxides for diabetic patients from 476±30 to 390±20 nmol/mg protein p〈0.05 and for control subjects from 350±36 to 198±30 nmol/mg protein p〈0.05). HDL conjugated diene formation decreased in both groups after diet but only significantly in the control group (55.4±7.5 to 53.2±6.7 nmol/mg protein for diabetic patients and 45.8±6.4 to 31.6±4.8 nmol/mg protein p〈0.05 for control subjects). There was a positive correlation between LDL lipid peroxide formation and percentage of cholesteryl ester linoleic acid in LDL from diabetic patients (r=0.61, p〈0.05) and control subjects (r=0.91, p〈0.01). Fatty acid composition of LDL was reflected in the composition of HDL. In the presence of HDL lipoprotein peroxidation decreased. This decrease in lipoprotein peroxidation was positively related to the percentage of linoleic acid in LDL (r=0.71, p〈0.05). This study confirms the close relationship between the fatty acid composition of LDL and HDL and demonstrates the importance of the fatty acid composition of the cholesteryl ester fraction in relation to LDL oxidation in diabetes. Linoleic acid in HDL appears to be a protecting factor against oxidation.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0428
    Keywords: Keywords Non-insulin-dependent diabetes mellitus ; low density lipoprotein oxidation ; low density lipoprotein fatty acids ; lipid peroxidation ; conjugated dienes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Oxidation of low density lipoprotein (LDL) plays an important role in the pathogenesis of atherosclerosis and is related to the fatty acid composition which is altered in diabetes mellitus. This study examines the relationship between the fatty acid composition of LDL and high density lipoprotein (HDL) and lipoprotein oxidation. A group of nine non-insulin-dependent diabetic (NIDDM) patients were compared to seven healthy control subjects before and after a high monounsaturated diet. Lipoproteins were isolated and oxidisability was measured by conjugated diene formation and lipid peroxide analysis. Serum HDL cholesterol was significantly lower in the diabetic patients. LDL cholesteryl ester linoleic acid in the diabetic patients was significantly higher at baseline and decreased after diet (p 〈 0.05) while oleic acid increased in both diabetic and non-diabetic subjects (p 〈 0.05). HDL cholesteryl ester oleic acid was lower in the diabetic patients compared with control subjects (p 〈 0.05) before diet and it increased significantly after diet (p 〈 0.05). LDL lipid peroxides and conjugated diene formation were related to LDL glycation (r = 0.46, p 〈 0.05 and r = 0.49, p 〈 0.05, respectively). Both decreased following diet (lipid peroxides for diabetic patients from 476 ± 30 to 390 ± 20 nmol/mg protein p 〈 0.05 and for control subjects from 350 ± 36 to 198 ± 30 nmol/mg protein p 〈 0.05). HDL conjugated diene formation decreased in both groups after diet but only significantly in the control group (55.4 ± 7.5 to 53.2 ± 6.7 nmol/mg protein for diabetic patients and 45.8 ± 6.4 to 31.6 ± 4.8 nmol/mg protein p 〈 0.05 for control subjects). There was a positive correlation between LDL lipid peroxide formation and percentage of cholesteryl ester linoleic acid in LDL from diabetic patients (r = 0.61, p 〈 0.05) and control subjects (r = 0.91, p 〈 0.01). Fatty acid composition of LDL was reflected in the composition of HDL. In the presence of HDL lipoprotein peroxidation decreased. This decrease in lipoprotein peroxidation was positively related to the percentage of linoleic acid in LDL (r = 0.71, p 〈 0.05). This study confirms the close relationship between the fatty acid composition of LDL and HDL and demonstrates the importance of the fatty acid composition of the cholesteryl ester fraction in relation to LDL oxidation in diabetes. Linoleic acid in HDL appears to be a protecting factor against oxidation. [Diabetologia (1996) 39: 667–676]
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Computational mechanics 18 (1996), S. 397-412 
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Flow simulation is a computational tool for exploring science and technology involving flow applications. It can provide cost-effective alternatives or complements to laboratory experiments, field tests and prototyping. Flow simulation relies heavily on high performance computing (HPC). We view HPC as having two major components. One is advanced algorithms capable of accurately simulating complex, real-world problems. The other is advanced computer hardware and networking with sufficient power, memory and bandwidth to execute those simulations. While HPC enables flow simulation, flow simulation motivates development of novel HPC techniques. This paper focuses on demonstrating that flow simulation has come a long way and is being applied to many complex, real-world problems in different fields of engineering and applied sciences, particularly in aerospace engineering and applied fluid mechanics. Flow simulation has come a long way because HPC has come a long way. This paper also provides a brief review of some of the recently-developed HPC methods and tools that has played a major role in bringing flow simulation where it is today. A number of 3D flow simulations are presented in this paper as examples of the level of computational capability reached with recent HPC methods and hardware. These examples are, flow around a fighter aircraft, flow around two trains passing in a tunnel, large ram-air parachutes, flow over hydraulic structures, contaminant dispersion in a model subway station, airflow past an automobile, multiple spheres falling in a liquid-filled tube, and dynamics of a paratrooper jumping from a cargo aircraft.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Computational mechanics 18 (1996), S. 397-412 
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Flow simulation is a computational tool for exploring science and technology involving flow applications. It can provide cost-effective alternatives or complements to laboratory experiments, field tests and prototyping. Flow simulation relies heavily on high performance computing (HPC). We view HPC as having two major components. One is advanced algorithms capable of accurately simulating complex, real-world problems. The other is advanced computer hardware and networking with sufficient power, memory and bandwidth to execute those simulations. While HPC enables flow simulation, flow simulation motivates development of novel HPC techniques. This paper focuses on demonstrating that flow simulation has come a long way and is being applied to many complex, real-world problems in different fields of engineering and applied sciences, particularly in aerospace engineering and applied fluid mechanics. Flow simulation has come a long way because HPC has come a long way. This paper also provides a brief review of some of the recently-developed HPC methods and tools that has played a major role in bringing flow simulation where it is today. A number of 3D flow simulations are presented in this paper as examples of the level of computational capability reached with recent HPC methods and hardware. These examples are, flow around a fighter aircraft, flow around two trains passing in a tunnel, large ram-air parachutes, flow over hydraulic structures, contaminant dispersion in a model subway station, airflow past an automobile, multiple spheres falling in a liquid-filled tube, and dynamics of a paratrooper jumping from a cargo aircraft.
    Type of Medium: Electronic Resource
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