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  • crashworthiness  (2)
  • Biochemistry  (1)
  • Epidemiology  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of epidemiology 10 (1994), S. 763-767 
    ISSN: 1573-7284
    Keywords: Epidemiology ; Parkinson's disease ; Prevalence ; Sentinel network
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Most of the epidemiological studies designed to determine the prevalence of Parkinson's disease (PD) in Portugal were hospital-based and the rates reported were around 1/1000. A sentinel network of general practitioners (GPs) has been in effect in the country since 1989, involving doctors with a relatively stable list of patients. This group of doctors notifies, every week, all the cases of certain selected diseases that may occur among the patients under their surveillance. On average, each doctor is responsible for 1500 to 1800 persons, of all ages and both sexes, whose main descriptive characteristics are known and updated every year. This led us to the idea of estimating the prevalence of Parkinson's disease in the community and to compare the estimated rates with hospital-based rates. One hundred and fifty general practitioners agreed to participate in a cross-sectional study which included a sample of 220,000 persons. The study took place between March and April 1992 and information on 291 PD patients was collected. Results show that among the study population, age-standardized rates were 1.4/1000 for males and 1.3/1000 for females. Sex-specific rates increase consistently with age in both sexes, reaching a level of 9/1000 in the oldest age group, ‘75 and more’ years. These results estimate a higher prevalence of PD than was determined previously through hospital-based studies and allowed us to determine that patients aged 65 years and more are much likely to be followed by their own GP, either because the disease its already controlled and they are specifically seeking medication or because they find it difficult to attend neurology clinics. To attain a more comprehensive care of such patients, a good collaboration should be guaranteed between the primary care level and the referral neurologists.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Nonlinear dynamics 8 (1995), S. 491-512 
    ISSN: 1573-269X
    Keywords: Multibody dynamics ; contact-impact ; Hertz models ; flexibility ; structural damping ; crashworthiness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A computer based formulation for the analysis of mechanical systems is investigated as a feasible method to predict the impact response of complex structural systems. A general methodology for the dynamic analysis of rigid-flexible multibody systems using a number of redundant Cartesian coordinates and the method of the Lagrange multipliers is presented. The component mode synthesis is then used to reduce the number of flexible degrees of freedom. In many impact situations, the individual structural members are overloaded giving rise to plastic deformations in highly localized regions, called plastic hinges. This concept is used by associating revolute nonlinear actuators with constitutive relations corresponding to the collapse behavior of the structural components. The contact of the system components is described using a continuous force model based on the Hertz contact law with hysteresis damping. The effect and importance of structural damping schemes in flexible bodies are also addressed here. Finally, the validity of this methodology is assessed by comparing the results of the proposed models with those obtained in different experimental tests where: a beam collides transversally with a rigid block; a torque box impacts a rigid barrier.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 40 (1997), S. 655-687 
    ISSN: 0029-5981
    Keywords: crashworthiness ; multibody dynamics ; flexible structures ; simulation ; design ; optimization ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Different formulations based on multibody dynamics are shown to be suitable for the development of a methodology for the impact simulation and crashworthiness design of railway vehicles. The proposed design methodology comprises different computer-aided tools of increasing complexity and accuracy which can be used with greater advantage and efficiency in the different design stages of railway stock. In general, the crashworthiness design methods and associated multibody dynamic tools which are presented in this paper require information to be obtained from numerical or experimental crush tests of specific structural components, subassemblies and critical energy absorption devices normally located in car extremities. This hybrid feature lends to the present design process various efficiency gains as a result of a better understanding of the crash and different collapse mechanisms and ease of use. To access the merits of the present methodologies some new designs are discussed and the application of the proposed numerical tools is illustrated for different structural configurations of car extremities. A formulation for the sensitivity analysis and optimization of planar constrained mechanical systems is also presented. An example of crashworthiness design of an end underframe model of a railway car is solved to demonstrate the use of the methodology. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 12 (1991), S. 1047-1057 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The Cα—C internal rotation in 2-methylpropionic, 2-methylthiopropionic (thiol and thion forms) and 2-methyldithiopropionic acids was studied by the ab initio SCF-MO method using 3-21G and 3-21G + d(0.65S) basis sets. Energies and structures of several conformations of these molecules, determined by gradient geometry refinement, are reported and used to assess the effects of oxygen-by-sulphur substitution on molecular properties. The nature and relative importance of intramolecular interactions involving both the α-methyl substituents and the C(=X)Y (X, Y= O or S) fragment are also discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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