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  • 1
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    German Medical Science; Düsseldorf, Köln
    In:  67. Jahrestagung der Deutschen Gesellschaft für Unfallchirurgie, 89. Tagung der Deutschen Gesellschaft für Orthopädie und Orthopädische Chirurgie und 44. Tagung des Berufsverbandes der Fachärzte für Orthopädie; 20031111-20031116; Berlin; DOC03dguA14-7 /20031111/
    Publication Date: 2003-11-11
    Keywords: ddc: 610
    Language: German
    Type: conferenceObject
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  • 2
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The natural circulation loop DANTON at the Dresden University of Technology was designed to investigate the thermohydraulic properties of integrated reactor concepts with a natural circulation driven primary loop. It is not possible to reach a stable two-phase flow in the loop without passing flow instabilities. At an equilibrium of heating and cooling power the flow oscillations can exist at nearly constant frequencies and amplitudes. The oscillating mass flow signal had been investigated by various methods: (a) autocorrelation function, (b) Fast Fourier transformation, (c) estimation of a temporal Liapunov-exponent and (d) reconstruction of the system attractor in a three-dimensional phase space. The selected time-series express a non-linear behaviour, however, they are not chaotic. In comparison to the usual methods the applied analysing methods yield additional information about system frequencies, sensitiveness to disturbances and properties due to non-linear and chaotic behaviour in a natural circulation loop.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-0431
    Keywords: Schlüsselwörter Kniegelenk • Individualendoprothetik • Computerunterstütztes Operieren • Kinematische Optimierung • Minimal-invasives Vorgehen ; Keywords Knee joint • Custom-made endoprosthesis • Computer-aided surgery • Kinematic optimization • Minimal invasive procedure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract A new method is presented which allows the construction and implantation of highly precise custom-made endoprostheses for knee joints. The procedure is based on a computer-aided subtraction process of three-dimensional CT data. Using the differences of the CT scans, the endprosthetic components are modelled by means of a newly developed software package. The implants are manufactured by CNC machines and stereolithography. The method enables the surgeon to reduce bone resections and ensures an exact profile of the bone-implant interface. Incorrect positioning will be avoided and the implantation process can be performed more easily while the size of the operative approach will be minimized. Better postoperative kinematics and reduction of shearing effects will lead to better results in the long run. The procedure offers a series of new possibilities to optimize monocondylar and bicondylar knee joint endoprostheses.
    Notes: Zusammenfassung Es wird ein neuartiges Verfahren vorgestellt, das die Fertigung und Implantation von hochexakten individuell geformten Oberflächenprothesen am Kniegelenk ermöglicht. Die Vorgehensweise basiert auf einem computergestützten Subtraktionsprozess von CT-Volumendaten. Aus den Differenzen wird das Implantat als dreidimensionales (3D-) Objekt rechnerisch modelliert und über einen sterolithografischen Zwischenschritt mittels CNC-Fräsung bzw. gusstechnisch hergestellt. Durch das Verfahren wird nicht nur eine möglichst geringe und den individuellen Gegebenheiten angepasste Knochenresektion ermöglicht, sondern auch eine optimale Kontaktfläche zwischen der Prothesenkomponente und dem Knochen gewährleistet. Positionierungsfehler werden reduziert, gleichzeitig wird der Implantationsvorgang erleichtert und die Größe des notwendigen Operationszugangs erheblich verringert. Durch die bessere Kinematik und die Reduktion der Scherkräfte ist nicht nur eine bessere Funktionalität sondern auch eine längere Haltbarkeit zu erwarten. Das Verfahren bietet mannigfaltige Optionen zur Verbesserung der herkömmlichen monokondylären und bikondylären Kniegelenksendoprothetik.
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  • 4
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We are interested in the thermal diffusion of a solitary wave in the anisotropic Heisenberg spin chain (HSC) with nearest-neighbor exchange interactions. The shape of the solitary wave is approximated by soliton solutions of the continuum HSC with on-site anisotropy, restricting ourselves to large width excitations. Temperature is simulated by white noise coupled to the system. The noise affects the shape and position of the solitary wave and produces magnons. Using implicit collective variables we describe the former effects and neglect magnons (i.e. we use the so-called adiabatic approximation). We derive stochastic equations of motion for the collective variables which we treat both analytically and numerically. Predictions for the mean values and the variances of the variables obtained from these equations are compared with the corresponding results from spin dynamics simulations. For the soliton position we find reasonable agreement between spin dynamics and the results of the collective variable treatment, whereas we observe deviations for the other collective variables. The stochastic dynamics of the position shows both a standard Brownian and a super-diffusive component. These results are analogous to results for the isotropic case, previously studied by some of the authors. In the present article we discuss in particular how the anisotropy enters the stochastic equations of motion and the quantitative changes it causes to the diffusion.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Allergy 58 (2003), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Sensitization of adenylate cyclase is a recently discovered phenomenon. Melatonin can induce a sensitized response of adenylate cyclase in ovine pars tuberalis cells where the receptor for melatonin is endogenously expressed. Although the mechanism is not fully understood, sensitization of adenylate cyclase may be an important part of the mechanism by which melatonin encodes daylength in the pars tuberalis of sheep and other animals. We used this as a hypothesis to search for a natural ligand that would activate adenylate cyclase in ovine pars tuberalis cells. The approach revealed pituitary adenylate cyclase activating polypeptide to be an indirect activator of adenylate cyclase in the ovine pars tuberalis. We discuss this in relation to the mechanism and importance of sensitization to the function to the pars tuberalis.
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  • 7
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Allergy 55 (2000), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1335
    Keywords: Regenerating liver ; Cell cycle ; O6-Methylguanine DNA transferase ; DNA alkylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary O6-Methylguanine DNA transferase activity was investigated in liver proteins obtained at various intervals after partial hepatectomy and/or after hydroxyurea-induced synchronization of the liver cell cycle. Liver proteins were incubated with 3H-methylated calf thymus DNA as previously described by Pegg et al. (1981). The loss of O6-methylguanine was measured by radiochromatography of DNA hydrolysates. The extent of O6-methylguanine repair differed during the cell cycle: the activity increased in late G1, reached a maximum in early S phase and declined in late S phase and G2M. These results indicate that hepatocytes are endowed with an increased DNA repair capacity for this promutagenic lesion during the period of highest transformation sensitivity in the cell cycle. Though increased, however, this repair potential does not, because of its exhaustibility, appear to be sufficient to prevent initiation of transformation after high doses of alkylating carcinogens.
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  • 9
    ISSN: 1432-2048
    Keywords: Chlorophyll (gene expression) ; Gene expression and light ; Light and gene expression ; Light-harvesting chlorophyll a/b-binding protein ; Phytochrome ; Ribulose-1.5-bisphosphate carboxylase ; Sinapis (light, mRNA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The amount of in-vitro translatable mRNA of the light-harvesting chlorophyll a/b-binding protein (LHCP) of photosystem II strongly increases in darkness (D) after a 5-min red-light pulse while continuous illumination of mustard seedlings with far-red (FR), red or white light leads only to a slight increase in the amount of translatable LHCP-mRNA. No increase can be observed after a long-wavelength FR (RG9-light) pulse. However, a FR pretreatment prior to the RG9-light pulse strongly increase LHCP-mRNA accumulation in subsequent D. This is not observed in the case of the mRNA for the small subunit of ribulose-1.5-bisphosphate carboxylase. The increase of LHCP-mRNA in D after a FR pretreatment can be inhibited by a reillumination of the seedlings with FR. The inhibition of LHCP-mRNA accumulation during continuous illumination with FR and the strong increase in D following a FR illumination was found to be independent of chlorophyll biosynthesis since no correlation between chlorophyll biosynthesis and translatable LHCP-mRNA levels could be detected. Even strong changes in the amount of intermediates of chlorophyll biosynthesis caused by application of levulinic acid or 5-aminolevulinic acid did not affect LHCP-mRNA levels. Therefore, we conclude that the appearance of LHCP-mRNA is inhibited during continuous illumination, even though illumination leads to a storage of a light singal which promotes accumulation of translatable LHCP-mRNA in D.
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  • 10
    ISSN: 1432-2048
    Keywords: Chloroplast (photooxidation, proteins) ; mRNA (chloroplast proteins) ; Nitrate reductase ; Photooxidation (chloroplast) ; Sinapis (plastid photooxidation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It was inferred from previous findings that a plastid-derived factor (plastidic factor) is involved in the transcriptional control of nuclear genes coding for proteins destined for the chloroplast. Photooxidative damage to the plastid destroys the ability of the organelle to give off this factor. Cytosolic enzyme levels are not impaired if plastids are damaged, and morphogenesis of seedlings is normal. The only exception found so far is nitrate reductase, a cytosolic enzyme, which is regulated by the cellas if it were a plastidic protein. In the present study we have shown that the plastids in the mesophyll of mustard (Sinapis alba L.) cotyledons, damaged by 3 h photooxidation in red light (6.8 W·m-2) and then returned to darkness or to continuous, non-photooxidative far-red light (cFR), recover from photooxidative damage. The rate of recovery is stimulated by phytochrome (operationally, cFR). Since the cytosolic enzyme nitrate reductase is affected by the different treatments in principally the same way as the levels of plastidic enzymes, we conclude that it is recovery of the plastids' ability to give off the plastidic factor rather than structural recovery which leads to recovery of gene expression and protein (and chlorophyll) re-accumulation. The extent of recovery varied according to the enzyme and this variation could be explained by different plastidic-factor requirements for gene expression. This explanation was confirmed by measurements of translatable mRNAs. It was found that LHCP-gene expression (light-harvesting chlorophyll a/b-binding protein of photosystem II) is far more sensitive to photooxidative damage of the plastids than SSU-gene expression (small subunit of ribulose-1.5-bisphosphate carboxylase). Correspondingly, recovery is expressed to a much greater extent in the latter than in the former case.
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