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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    World journal of surgery 14 (1990), S. 807-818 
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les progrès en micro- ou macroréimplantations se soldent par des taux de survie plus importants dans les amputations traumatiques. Les raisons sont l'entraÎnement intensif et les nombreuses expériences dues à une application générale des techniques de la microchirurgie. La plupart des doigts ou membres amputés peut survivre car le temps d'ischémie peut Être allongé en utilisant la conservation par le froid ou la perfusion. La transposition de vaisseaux homo ou hétérodigitaux, les indications élargies d'interposition veineuse aussi bien que de transplantation hétérotope permettent la conservation des extrÊmités mÊme dans les lésions par écrasement ainsi que dans de nombreuses amputations multiples accompagnées de contusion ou d'avulsion. De nos jours, la réimplantation digitale avec anastomose microvasculaire de l'articulation interphalangienne distale est techniquement réalisable chez l'adulte. Chez l'enfant, la réimplantation est une indication essentielle en cas d'amputation des doigts. On peut garder la longueur nécessaire du membre en posant un fixateur externe. Des lambeaux libres en urgence ou un transfert composite en “urgence différée” peuvent fournir un tissu de couverture fiable. La reconstruction secondaire des défects d'os ou de tendons et des éventuelles greffes de nerfs conduisent finalement à une amélioration des résultats fonctionnels de l'activité quotidienne et de loisirs et à une rééducation professionnelle précoce.
    Abstract: Resumen El progreso en las micro- o macrorreplantaciones se evalua mediante las mayores tasas de supervivencia de miembros o de las partes que han sido amputados. Tal progreso se ha sido logrado gracias al intenso trabajo de adiestramiento en laboratorios y la voluminosa experiencia derivada de la aplicación de las técnicas de microcirugía. Un mayor nÚméro de dedos o de extremidades puede sobrevivir en virtud de la preservación en frio o mediante perfusión. La transposición vascular homo o heterodigital, la más amplia indicación para interposición de injertos venosos, así como el transplante heterotópico, permiten la conservación de extremidades aÚn en casos de lesiones por aplastamiento y de desastrosas amputaciones mÚltiples combinadas con contusión o avulsión. En la actualidad es técnicamente factible la reimplantación digital microquirÚrgica con las anastomosis vasculares distales a la articulación interfalángica distal en adultos. El mantenimiento de la longitud de la extremidad es factible por medio de la fijación externa. Bajo la clasificación de “urgencia diferida,” pueden realizarse colgajos libres o transferencias de colgajos compuestos que proveen una confiable cobertura con tejidos blandos. La reconstrucción secundaria de los defectos óseos, reparación tendinosa, y eventuales injertos de nervios, debe ser programadas, todo lo cual resulta en una mejoría de los resultados funcionales en la realización de las actividades diarias, así como para la readaptación profesional temprana.
    Notes: Abstract Progress in micro- or macroreplantation has resulted in higher survival rates of formerly amputated parts. Progress has been made as a result of intensive laboratory training and considerable experience due to the popular application of microsurgical techniques. More amputated digits or limbs may survive because the time of ischemia can be exceeded in using cold storage or perfusion. Homo- or heterodigital vessel transposition, expanded indications for vein graft interposition, as well as heterotopic transplantation allow for extremity preservation even in crush injuries, and in disastrous multiple amputations combined with contusion or avulsion. Nowadays, microvascular digital replantation with vessel anastomosis distal to the distal interphalangeal joint in adults is technically feasible. Finger amputations in children are a prime indication for replantation. Maintenance of extremity length is possible in applying external fixation. Emergency free flaps or compound tissue transfer under the “Urgence differée” condition may provide reliable soft tissue coverage. Secondary reconstruction with regard to bone defects, tendon repair, and eventual nerve grafting have to be aspired, finally leading to an improvement of functional results in daily and leisure activities as well as in early professional readaptation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 31 (1985), S. 187-195 
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A nocturnal low-level jet characterized by a distinct inertial oscillation lasting from around sunset until sunrise the next day was observed during the coastal experiment PUKK. The phenomenon appeared over an area of at least 40 km in diameter; it thus had a mesoscale extension. We were able not only to observe this fine case but also to simulate it by an integrated dynamical PBL model.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 20 (1981), S. 497-513 
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An internally interactive radiative-convective model for an inversion-capped planetary boundary layer (PBL) with stratus or stratocumulus convection is presented. It includes a parameterization scheme for the radiative processes based on the radiative transfer equation, which allows calculations of the radiative net flux divergence as an internal model parameter. The accuracy of this parameterization is tested by comparison to a high resolution spectral radiation model, showing an encouraging agreement. Typical profiles of the radiative net flux divergence in an inversion-capped cloudy PBL show two distinct regions of radiative cooling near the top of the cloud and in the upper part of the inversion, and two regions of radiative heating in the vicinity of the cloud base and the inversion base. Therefore for the first time both the turbulence and the radiation characteristics of the PBL can be derived as internal model parameters. Two radiosonde ascents — one from Santa Monica, California, one from weather ship ‘M’ in the Northern Atlantic — are used in order to compare model results with routine measurements. In both cases the inversion height (i.e. the difference between surface pressure and pressure at the inversion level) is slightly underestimated, whereas the vertical profiles of dry and moist static energy as well as the total water content and the specific humidity agree fairly well in the well-mixed layer. The description of the radiative processes according to Lilly (1968) and Kahn and Businger (1979) is also investigated for both cases. Lilly's concept failed for the case over the Northern Atlantic, and the suggestion of Kahn and Businger failed for the Californian coast, thus demonstrating the limited accuracy and applicability of such simple parameterization schemes.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 11 (1977), S. 329-354 
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The energy-budget concept is used together with a high resolution spectral radiation model to study the time and height variation of the sensible heat flux and of the eddy thermal diffusivity for an actual case up to 50 m above ground. A data set of 32 h is chosen for this study. Time-height cross-sections of the local enthalpy changes, and the radiative and the sensible heat flux divergences are presented, which show the interaction of the two energy fluxes. It can be seen, for example, that during the transient hours from night to day the sensible heat flux divergence plays an outstanding role in the warming of the atmosphere, while during the clear night radiative cooling exceeds the cooling caused by the sensible heat flux. For the layer under consideration (0-50 m) a constancy of the sensible heat flux within 10% is obtained for seven hours only, namely for the time around noon and in the early afternoon. Selected night-time profiles of the thermal diffusivity are shown, which have their maximum below 48.3 m. The accuracy of the energy-budget method is studied in detail. The tests show that a high accuracy, with errors even less than 10% for some hours, can be expected, if special micrometeorological studies are made during the field phase and a layer depth of 50 cm or less is used in the radiation model.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 20 (1981), S. 485-495 
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In an inversion-capped planetary boundary layer (PBL), the structure of the turbulent fluxes as well as the height of the inversion are determined by the interaction of turbulent mixing in the PBL, large-scale subsidence above the PBL and radiational cooling. Here the sensitivity of the inversion height and of the turbulent fluxes due to radiational processes is investigated with the aid of a three-layered model for a well mixed PBL. For an example of the Trade-Wind region, the inversion height (i.e., the difference between surface pressure and pressure at the inversion level) varies between 46 and 257 mb and the surface flux of moist static energy between 417 and 99 W m-2, if the (mean) radiative net flux divergence for both the inversion and the well-mixed layer is changed over a reasonable range of values. None of the parameterization schemes existing in the literature is able to describe these radiational effects in an appropriate way. This is due to the fact that these parameterizations are either not or not flexibly enough linked to the thermodynamical model parameter. Therefore the demand for an adequate parameterization of the radiational influence in a well-mixed PBL under a subsidence inversion is obvious.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 37 (1986), S. 323-341 
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In higher-order closure models at least the pressure redistribution and the dissipation of the turbulent kinetic energy and the temperature variance have to be parameterized. Due to this, the introduction of proportionality coefficients — the so-called closure parameters — is forced, which have to be determined before the model is used. We compare a group of models which use the return-to-isotropy hypothesis (Rotta, 1951) to describe the pressure redistribution and assume local isotropy for the smallest eddies in order to parameterize the dissipation. Special concern is given to the method of Mellor and Yamada (1982). Some of the closure parameters are re-derived on the basis of sensitivity studies requiring that both shear production and buoyancy behave in a realistic way if pressure redistribution or dissipation is changed by varying the closure parameters. This set of parameters is compared with those obtained by fitting to experimental data, by use of the Monin-Obukhov similarity theory and by considering ratios of variances, covariances and mean flow gradients, respectively. It is shown that the various sets of closure parameters are at least of the same order. The differences give some insight into the advantages and disadvantages of the various determination procedures. However, the general accordance of the different parameter sets supports the assumption of universal constants.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 81 (1996), S. 147-166 
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Non-Gaussianity effects, first of all the influence of the third and fourth moments of the velocity probability density function, have to be assessed for higher-order closure models of turbulence and Lagrangian modelling of turbulent dispersion in complex flows. Whereas the role and the effects of the third moments are relatively well understood as essential for the explanation of specific observed features of the fully developed convective boundary layer, there are indications that the fourth moments may also be important, but little is known about these moments. Therefore, the effects of non-Gaussianity are considered for the turbulent motion of particles in non-neutral flows without fully developed convection, where the influence of the fourth moments may be expected to be particularly essential. The transport properties of these flows can be characterized by a diffusion coefficient which reflects these effects. It is shown, for different vertical velocity distributions, that the intensity of turbulent transport may be enhanced remarkably by non-Gaussianity. The diffusion coefficient is given as a modification of the Gaussian diffusivity, and this modifying factor is found to be determined to a very good approximation by the normalized fourth moment of the vertical velocity distribution function. This provides better insight into the effect of fourth moments and explains the varying importance of third and fourth moments in different flows.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-0662
    Keywords: Biosphere-atmosphere exchange ; dry deposition ; tlux-gradient relationships ; HNO3 fluxes ; NO fluxes ; NO2 fluxes ; ozone fluxes ; resistance approach ; turbulent transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A modified profile method for determining the vertical deposition (or/and exhalation) fluxes of NO, NO2, ozone, and HNO3 in the atmospheric surface layer is presented. This method is based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's surface and the chemical reactions among these trace gases. The analysis (aerodynamic profile method) includes a detailed determination of the micrometeorological quantities (such as the friction velocity, the fluxes of sensible and latent heat, the roughness length and the zero plane displacement), and of the height-invariant fluxes of the composed chemically conservative trace gases with ‘group’ concentrations c 1=[NO]+[NO2]+[HNO3], c 2=[NO2]+[O3]+3/2·[HNO3], and c 3=[NO]−[O3]−1/2·[HNO3]. The fluxes of the ‘individual’ species are finally determined by the numerical solution of a system of coupled nonlinear ordinary differential equations for the concentrations of ozone and HNO3 (‘decoding’ method). The parameterization of the fluxes is based on the flux-gradient relationships in the turbulent region of the atmospheric surface layer. The model requires only the vertical profile data of wind velocity, temperature and humidity and concentrations of NO, NO2, ozone, and HNO3. The method has been applied to vertical profile data obtained at Jülich (September 1984) and collected in the BIATEX joint field experiment LOVENOX (Halvergate, U.K., September 1989).
    Type of Medium: Electronic Resource
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