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  • 1
    Digitale Medien
    Digitale Medien
    Alternative Splicing in the Control of Gene Expression (1989)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 23 (1989), S. 527-577 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.ge.23.120189.002523
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Dielectric dispersions in bacteriorhodopsin (1986)
    Springer
    Journal of biological physics 14 (1986), S. 15-20 
    Details
    ISSN: 1573-0689
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Notizen: Abstract Dispersion effects in bacteriorhodopsin both in suspension and incorporated into liposomes have been studied by measuring the changes in the dielectric properties induced by electric and magnetic fields at low and medium frequencies. The samples exhibit very high values of relative permittivity and dielectric loss. Dispersions have been measured up to 200 kHz and are believed to be due to the reorientation of the bacteriorhodopsin chromophore within the membrane fragments. A study of relaxation times vs temperature shows a transition at 28°C, the same temperature as found using other techniques.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01857980
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  • 3
    Digitale Medien
    Digitale Medien
    The effects of irradiation and hydration upon the mechanical properties of tendon (1996)
    Springer
    Journal of materials science 7 (1996), S. 645-650 
    Details
    ISSN: 1573-4838
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Irradiation sterilization is in wide use among tissue banks, for both hard and soft tissue grafts. Irradiation of tendon can impair its mechanical properties. Following implantation of a tendon graft, re-vascularization and resorption processes reduce its mechanical performance. Tendon with severely impaired properties may not be suitable for use as a load-bearing graft, e.g. as anterior cruciate ligament replacement. An important factor determining the extent of the reduction of the mechanical performance is the condition of the tendon during irradiation, especially the presence of water. There has not yet been a study of the effects of both irradiation dose and hydration on tendon mechanical properties. This study measured the changes in tensile mechanical properties, including strength and stiffness, following γ irradiation doses of 15 kGy (1.5 MRad) and 25 kGy (2.5 MRad), in the frozen state and following freeze-drying. The strength of the freeze-dried irradiated tendons was lower compared to fresh tendons, whereas the strength of the frozen irradiated tendons was very similar to that of the fresh. The tangent modulus of both of the freeze-dried irradiated groups were lower than the fresh tendons, as was the 15 kGy frozen group. The modulus of the 25 kGy frozen irradiated group was similar to the fresh. The general pattern of the results indicate that the two freeze-dried tendon groups were more affected than the frozen irradiated, and of the frozen irradiated groups the 25 kGy group was least affected. The results fit well with suggested mechanisms for the action of irradiation upon collagen; that intramolecular crosslinking and scission of the tropocollagen α chains occur when water is present, and α chain scission alone occurs when water is absent. lrradiation of tendons for use as grafts may produce minimal deleterious changes if the irradiation is performed while the tendon is frozen with water present.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00123402
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  • 4
    Digitale Medien
    Digitale Medien
    Fluctuations, Dissipation and Heating in the Corona (1999)
    Springer
    Space science reviews 87 (1999), S. 269-275 
    Details
    ISSN: 1572-9672
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Mechanisms for the deposition of heat in the lower coronal plasma are discussed, emphasizing recent attempts to reconcile the fluid and kinetic perspectives. Structures at the MHD scales are believed to act as reservoirs for fluctuation energy, which in turn drive a nonlinear cascade process. Kinetic processes act at smaller spatial scales and more rapid time scales. Cascade-driven processes are contrasted with direct cyclotron absorption, and this distinction is echoed in the contrast between frequency and wavenumber spectra of the fluctuations. Observational constraints are also discussed, along with estimates of the relative efficiency of cascade and cyclotron processes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1005125223740
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  • 5
    Digitale Medien
    Digitale Medien
    The thin filaments of smooth muscles (1985)
    Springer
    Journal of muscle research and cell motility 6 (1985), S. 669-708 
    Details
    ISSN: 1573-2657
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Contraction in vertebrate smooth and striated muscles results from the interaction of the actin filaments with crossbridges arising from the myosin filaments. The functions of the actin based thin filaments are (1) interaction with myosin to produce force; (2) regulation of force generation in response to Ca2+ concentration; and (3) transmission of the force to the ends of the cell. The major protein components of smooth muscle thin filaments are actin, tropomyosin and caldesmon, present in molar ratios of 28:4:1 respectively. Other smooth muscle proteins which may be associated with the thin filaments in the cell are filamin, vinculin, α-actinin, myosin light chain kinase and calmodulin. We have reviewed the structural and functional properties of these proteins and where possible we have suggested what their function and mechanism of action may be. We propose that actin and tropomyosin are involved in the force producing interaction with myosin, and that this interaction is controlled by a Ca2+-dependent mechanism involving caldesmon, tropomyosin and calmodulin. Vinculin, α-actinin and filamin appear to be involved in the attachment of the thin filaments to the cell membrane and their spatial organization within the cell. We conclude that the filaments of smooth muscles share many common properties with those from skeletal muscle, but that they are also quite distinct in terms of both their caldesmon based regulatory mechanism and their mode of organization into a contractile apparatus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00712237
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Measurement of dominant eigenvalues in cracked body problems (1989)
    Springer
    International journal of fracture 39 (1989), S. 15-24 
    Details
    ISSN: 1573-2673
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Beschreibung / Inhaltsverzeichnis: Résumé On expose brièvement une méthode optique consistant à appliquer en parallèle la photo-élasticité sous contraintes figées et l'interférométrie sur bandes de Moiré à hautes densités, pour l'étude des effets tridimensionnels dans les solides fissurés. On utilise ensuite cette méthode à la mesure de l'eigenvalue dominante à l'intersection suivant un angle droit d'un front de fissure droit avec une surface libre, sous une sollicitation de Mode I. On détermine également la variation de l'eigenvalue dans une zone de transition au voisinage de la surface libre. Le résultat relatif à cette dernière est en bonne concordance avec les résultats analytiques.
    Notizen: Abstract A refined optimal method consisting of the tandem application of frozen stress photoelasticity and high density moire interferometry for studying three dimensional effects in cracked bodies is briefly reviewed. It is then employed to measure the dominant eigenvalue at the right angle intersection of a straight front crack with a free surface under mode I loading. The variation of the eigenvalue through a transition zone near the free surface is also determined. The free surface result is found to be in agreement with analytical results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00047436
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  • 7
    Digitale Medien
    Digitale Medien
    Analytical and experimental studies of the surface flaw (1988)
    Springer
    Experimental mechanics 28 (1988), S. 194-200 
    Details
    ISSN: 1741-2765
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract This paper uses the Newman-Raju model, the Paris crack-growth-rate law and a fixedR ratio to demonstrate the analytical considerations associated with predicting stress-intensity distributions and fatigue crack growth of surface flaws under conditions of small-scale yielding. Subsequently, problems which lie outside the realm of the model used in the analytical description are presented. It is concluded that, while the model employed provides remarkable predictive capability in a variety of surface-flaw problems, many exceptional cases remain to be modeled.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02317573
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  • 8
    Digitale Medien
    Digitale Medien
    Interpretation of experimental data for Poisson's ratio of highly nonlinear materials (1999)
    Springer
    Experimental mechanics 39 (1999), S. 356-362 
    Details
    ISSN: 1741-2765
    Schlagwort(e): Engineering strain ; nonlinear ; Poisson's ratio ; strain dependent ; true strain ; auxetic
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The Poisson's ratio of a material is strictly defined only for small strain linear elastic behavior. In practice, engineering strains are often used to calculate Poisson's ratio in place of the mathematically correct true strains with only very small differences resulting in the case of many engineering amterials. The engineering strain definition is often used even in the inelastic region, for example, in metals during plastic yielding. However, for highly nonlinear elastic materials, such as many biomaterials, smart materials and microstructured materials, this convenient extension may be misleading, and it becomes advantageous to define a strainvarying Poisson's function. This is analogous to the use of a tangent modulus for stiffness. An important recent application of such a Poisson's function is that of auxetic materials that demonstrate a negative Poisson's ratio and are often highly strain dependent. In this paper, the importance of the use of a Poisson's function in appropriate circumstances is demonstrated. Interpretation methods for coping with error-sensitive data or small strains are also described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02329817
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  • 9
    Digitale Medien
    Digitale Medien
    On the extraction of stress-intensity factors from near-tip photoelastic data (1986)
    Springer
    Experimental mechanics 26 (1986), S. 313-318 
    Details
    ISSN: 1741-2765
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Existing algorithms and a new algorithm called ‘quadratic’, for extracting stress-intensity factors (SIF) from frozen-stress photoelastic data are evaluated for application to near-tip data in three-dimensional problems. It is shown that for this class of problems, modifications to some of the existing algorithms may be necessary, in some cases, in order to ensure reliable SIF values. But that for all the algorithms, the two-parameter form of the governing equations of linear-elastic fracture mechanics (LEFM) is sufficient for use with near-tip data, even for complex three-dimensional geometries.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02320145
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  • 10
    Digitale Medien
    Digitale Medien
    Temperature and rate effects on stable crack growth in a particulate composite material (1996)
    Springer
    Experimental mechanics 36 (1996), S. 290-295 
    Details
    ISSN: 1741-2765
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract In this study, edge cracked sheet specimens made from polybutadiene rubber embedded with hard particles were used in crack propagation tests. Crack propagation tests were conducted under two crosshead speeds (2.54 mm/min and 12.7 mm/min) at three temperatures (−53.9°C, 22.2°C and 73.9°C). The experimental data were analyzed and the crack growth resistance curves and the crack growth rate versus the Mode I stress intensity factor were plotted. Based on these experimental results, the effects of temperature and loading rate on the crack growth behavior were investigated and the results are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02318021
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