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  • 11
    Electronic Resource
    Electronic Resource
    Further prospective evidence of a circadian variation in the frequency of call for sudden cardiac death (1995)
    Springer
    Intensive care medicine 21 (1995), S. 45-49 
    Details
    ISSN: 1432-1238
    Keywords: Sudden cardiac death ; Circadian rhythm ; Two-harmonic regression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective To determine whether in a larger data base call for sudden cardiac death exhibits a specific circadian rhythm similar to that recently demonstrated by Levine et al. Design and setting The time of the day of calls received for out-of-hospital cardiac arrests (OOHCA) prospectively registered between 1983 and '90 by 7 major Belgian prehospital EMS-MICU services. Chrono-biologic assessment was made by two-harmonic linear regression analysis of the data tabulated by hour of the day. The hourly distribution of calls for OOHCAS was subjected to Fourier transformation resulting in a periodogram. Patients 3471 OOHCAs with presumed cardiac etiology and age of more than 18 years versus 2007 impatients registered in the same period. Measurements and results Significant and remarkably similar circadian patterns were found (R-square=0.84) for the cardiac origin OOHCAs and the ventricular fibrillation OOHCAs. There is a low incidence during the night and an increased incidence from 6 a.m. until noon with an additional early afternoon-peak. The data were always better fitted when applying sinusoids with periods of 8 and 24 h instead of 12 and 24 h. Our observed circadian distribution resembles the reported circadian variation of ischaemic episodes, ventricular tachycardia and acute myocardial infarction in the awake hours. The time distribution of OOHCA (cardiac origin) differs significantly from OOHCA (non-cardiac origin) and from in-hospital cardiac arrests. The in-hospital CA pattern shows less deviation. The age dependent variation in the incidence of cardiac origin OOHCAs, was not obvious for the ventricular fibrillation subgroup. Conclusion Knowledge about the cyclical nature of incidence of cardiac arrests is useful to improve intersystem comparisons and make sound decisions about prophylaxis, treatment and allocation of resources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02425153
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  • 12
    Electronic Resource
    Electronic Resource
    Kinetic investigations on the photopolymerization of di- and tetrafunctional methacrylic monomers in polymeric matrices. ESR and calorimetric studies. II. Postpolymerization reactions (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2785-2791 
    Details
    ISSN: 0887-624X
    Keywords: postpolymerization reactions ; ESR ; polymeric matrices termination reactions ; H-transfer reactions ; kinetic constants ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction kinetics in the dark of photopolymerized mono- and dimethacrylates in a polymeric binder has been studied. Electron spin resonance spectroscopy (ESR) provided useful information regarding the nature of the radicals involved in postpolymerization reactions. Computer simulations were performed to study the decay of the propagating radicals by considering normal bimolecular termination and transfer reactions of the radicals to the binder. Differences were found in the termination reactions for mono- and difunctional monomers when they were photopolymerized in a solid medium. Absolute kinetic constants for H-transfer reaction with the binder, relative kinetic rate constants for radical-radical coupling, and average lifetimes for the radicals have been calculated. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2785-2791, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 13
    Electronic Resource
    Electronic Resource
    Kinetic investigations on the photopolymerization of di- and tetrafunctional (meth)acrylic monomers in polymeric matrices. ESR and calorimetric studies. I. Reactions under irradiation (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2775-2783 
    Details
    ISSN: 0887-624X
    Keywords: photopolymerization kinetics ; ESR ; polymeric binders ; radical environment ; photocalorimetry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photopolymerization of several di- and tetrafunctional (meth)acrylic monomers in the presence of a styrene-butadiene-styrene polymeric matrix (SBS) has been studied. Electron spin resonance spectroscopy (ESR) and differential scanning photocalorimetry (photo-DSC) were used as monitoring techniques to identify the photogenerated radicals and analyze photopolymerization profiles, radical environments, and radical secondary reactions. The study of the photopolymerization and/or photocrosslinking reactions of these monomers in the solid media was carried out by taking into consideration different factors, such as the influence of both monomer and photoinitiator structures on the hydrogen abstraction in the binder with formation of benzylic and allylic radicals, the polymerization of the monomers itself and the hydrogen abstraction reaction in the polymerized acrylic chains. Finally, irradiation of the system SBS/photoinitiator in the absence of monomer was also accomplished. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2775-2783, 1998
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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