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  • Articles: DFG German National Licenses  (10)
  • 1985-1989  (10)
  • Computational Chemistry and Molecular Modeling  (6)
  • Epidemiology  (4)
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  • Articles: DFG German National Licenses  (10)
Material
Years
Year
  • 1
    ISSN: 1432-1246
    Keywords: Arc welding ; Respiratory symptoms ; Lung function ; Epidemiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An epidemiological, cross-sectional study was conducted in order to assess non-neoplasic effects on the lung due to chronic exposure to arc welding fumes and gases. The study involved 346 arc welders and 214 control workers from a factory producing industrial vehicles. These workers (welders and controls) had never been exposed to asbestos. Respiratory impairments were evaluated by using a standardized questionnaire, a clinical examination, chest radiophotography and several lung function tests (spirometry, bronchial challenge test to acetylcholine, CO transfer tests according to the breath-holding and the steady-state methods, N2 washout test). The only significant differences between the welders overall compared to the controls were a slightly higher bronchial hyper-reactivity to acetylcholine and a lower lung diffusing capacity for CO in the welders. However, non-specific, radiologic abnormalities (reticulation, micronodulation) and obstructive signs were more frequent in the most exposed welders (welding inside tanks) than in welders working in well ventilated workplaces. The nature of the metal welded (mild-steel, stainless steel, aluminium) did not seem to have an influence on respiratory impairments. In the mild-steel welders, respiratory symptoms (dyspnoea, recurrent bronchitis) and obstructive signs were more frequent in the welders using a manual process than in the welders involved with the semi-automatic process (MIG). For all the workers (welders and controls), smoking had a markedly adverse effect on respiratory symptoms and lung function. Moreover, smoking seemed to interact with welding since CO lung transfer was more impaired in smoking welders than in smoking controls.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1246
    Keywords: Arc welding ; Respiratory health ; Epidemiology ; Longitudinal study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The respiratory health of 138 arc welders and 106 control subjects in the same company was studied in 1981 and in 1986. Most of the subjects welded mild steel using the Metal Inert Gas (MIG) process. The controls were workers in the same company, not exposed to any known pulmonary risk. The welders and controls in the analysis had not changed their professional activity nor their smoking habits during these five years. The examinations consisted of a questionnaire on respiratory symptoms, a thoracic auscultation, a chest X-ray and lung function tests: flow-volume curve and steady state CO transfer test. The examinations in 1986 confirmed the risk of non specific radiological impairment (pulmonary reticulo-micronodulation) and of obstruction in the small bronchi, which had already been observed in 1981 in the arc welders in this company. These impairments did not seem to have evolved more than in the controls, but do however justify regular surveillance of the respiratory health of arc welders.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1246
    Keywords: Epidemiology ; Respiratory symptoms ; Man-made mineral fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A respiratory health questionnaire was administred to the workers producing man-made mineral fibers in three glasswool and two rockwool plants in France, in order to detect adverse effects resulting from fiber exposure. The mean ages of the 2024 male participants ranged from 32 to 41 years. The standardized questionnaire was filled in by the industrial physicians: occupational history, smoking habits, respiratory symptoms (cough, phlegm, dyspnea, asthma), irritative complaints of the upper airways (nasal fossae and sinuses, pharynx and larynx) were all recorded. Multiple unconditional logistic regression was used to test for a relationship between possible explanatory variables and these symptoms. The prevalence of respiratory symptoms (cough, phlegm, dyspnea) was strongly correlated with age and increased markedly among current smokers. Having adjusted for these confounding factors, significantly elevated Odds Ratios (ORs) for cough and phlegm were observed among the workers of one plant (51% of the whole study population) who had been exposed to fibers for a long time. In the same plant, the ORs for complaints of nasal fossae and sinuses increased significantly with the duration of fiber exposure, and one elevated OR was observed for pharyngeal and laryngeal symptoms. These findings were not consistent with the results observed in the four other plants (49% of the study population), since ORs for all these symptoms were either low or not significantly increased according to the duration of fiber exposure. This lack of similarity among plants could be explained either by differences in interviewers, age, seniority and tobacco consumption, or by secular changes in the industrial processes involved. The positive results observed contrast with a negative lung function study previously carried out in the same plant. Furthermore, the literature provides only one study reporting similar positive findings concerning pharyngeal and laryngeal complaints.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 235 (1988), S. 241-244 
    ISSN: 1432-1459
    Keywords: Multiple sclerosis ; Epidemiology ; Incidence ; Central Europe ; Periodic fluctuations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary For diseases of unknown aetiology, the question as to whether the incidence is constant or variable is very important. A study on multiple sclerosis in a defined northern area of the German Democratic Republic showed a prevalence of 68.6 and an incidence rate of 3.0. Retrospective and prospective investigations concerning an observation period of 22 years revealed cyclic periods (6–7 years) of high incidence rates (up to 4.5) interrupted by shorter intervals (4–5 years) with low rates (about 1.8). The differences (1963–1968 vs. 1969–1973, 1974–1978 vs. 1979–1983) are significant. In accordance with the findings of Kurtzke et al. on a cyclic outbreak of multiple sclerosis in the Faroes and Iceland, our results are considered to be a consequence of environmental factors, such as epidemic viral infections.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 33 (1988), S. 445-465 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A formalism is developed for the construction of relativistic symmetry-adapted molecular basis functions under consideration of time reversal invariance. The theory is applicable to the finite double point groups Cn, Cnh, Sn, Cnv, Dn, Dnd, Dnh, T, Th, Td, O, and Oh. It is based on the LCAO method. A projection operator technique is employed to construct molecular symmetry orbitals from atomic orbitals. The search for linearly independent basis function is simplified by means of group theoretical considerations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 6 (1985), S. 1-4 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: It is noticed that inclusion of an electrostatic term in the molecular-mechanical treatment of hydrocarbons would compel the nonbonding parameters of different force fields to become more alike than they are at present. Apart from removing the discontinuity in passing from the calculation of an unfunctionalized parent compound to the calculation of its functionalized derivatives, it is expected that the inclusion would improve results for the hydrocarbons themselves.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 9 (1988), S. 18-24 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: This article examines the numerical estimation of molecular surface areas within the model of overlapping atomic spheres. One has the choice of either basing the estimate on all elements that contribute to the surface, or of ignoring systematically some elements in the interatomic clefts. It is argued that the second choice, even though more approximate, implicitly improves on the model and is to be preferred. Since surface areas are not measurable, the demonstration is unavoidably roundabout, relying mostly on correlation analysis. Among the regressors occur two compounded parameters. One, ratio of the surface area of the equivalent sphere to the surface area, is interpreted as a measure of molecular globularity. It reflects the molecular axis-ratio and surface convolution. The other, ratio of the surface area to the volume, is interpreted as a measure of the global congestion of a chemical residue. Together with a measure of the local congestion at the point of attachment, it affects the steric hindrance that a residue offers. The relation between the surface area and the number of valence electrons is also discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 7 (1986), S. 144-152 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A nonanalytical procedure is proposed to calculate the surface area and cross-sectional areas of molecules. Results are reviewed for about 70 species comprising alkanes, acyclic and cyclic, alkyl halides, and alcohols. By regression analysis, relationships are detected between surface areas or segment areas and physical properties. Computed cross-sectional areas are confronted with adsorption values. Four ways are proposed to define quantitatively the intuitive notion of «molecular globularity».
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 9 (1988), S. 650-661 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We apply Shanno's conjugate gradient algorithm to the problem of minimizing the potential energy function associated with molecular mechanical calculations. Shanno's algorithm is stable with respect to roundoff errors and inexact line searches and converges rapidly to a minimum. Equally important, this algorithm can improve the rate of convergence to a minimum by a factor of 5 relative to Fletcher-Reeves or Polak-Ribière minimizers when used within the molecular mechanics package AMBER. Comparable improvements are found for a limited number of simulations when the Polak-Ribière direction vector is incorporated into the Shanno algorithm.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 801-809 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A 31.5 picosecond (ps) MD calculation has been completed for the 1:1 enzyme-ligand complex between porcine pancreatic elastase (PPE) and acetyl-alanine-proline-alanine (APA). The 1:2 complex studied crystallographically at product saturation conditions precludes the study of a 1:1 complex (PPE and APA1); this objective has been achieved by computational methods described here. The acetyl group of the ligand was found to occupy two neighboring sites, one within the primary specificity site and the other out into solution. The primary change of the ligand structure is ψ1 torsion angle being 171.5°. Supported by an interactive graphic display, the dynamical fluctuations of a smaller ligand compared with the width of the active site as PPE were observed by the MD simulation, although the complex has not been detected by any spectroscopic method.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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