11,685 research outputs found
Molekulare Signalwege der aseptischen Endoprothesenlockerung (Molecular pathways in aseptic loosening of orthopaedic endoprosthesis)
Abstract Operative joint replacement to treat disabling joint conditions secondary to degenerative and inflammatory arthritides has become one of the most efficacious and cost-effective procedures to relieve pain and restore joint function. However, prosthetic implants are not built to last forever and osteolysis and aseptic loosening has been associated with prosthetic arthroplasties since their introduction. The functional life of a synthetic joint is influenced by many factors including the material of the implant, operation procedures and the surgeon involved, as well as patient-related factors. Although promising developments have been achieved in this field, more than 10% of all implants still have to undergo operative revision within 15 years after the initial operation. Failure due to sepsis, fractures and dislocations has become rare; premature loosening of implants on the other hand is becoming much more important. Prosthetic loosening without concurrent infection or trauma is called aseptic loosening. It is generally accepted that small particles ("wear debris") and activated macrophages play a key role in aseptic loosening. The pathophysiology of this condition, however, is still not very well characterized. In this article, we review the molecular mechanisms and signal pathways that were unravelled as responsible factors for loosening orthopaedic implants. Finally, we discuss possible novel strategies for future therapeutic approaches
Tip cap for a rotor blade
A replaceable tip cap for attachment to the end of a rotor blade is described. The tip cap includes a plurality of walls defining a compartment which, if desired, can be divided into a plurality of subcompartments. The tip cap can include inlet and outlet holes in walls thereof to permit fluid communication of a cooling fluid there through. Abrasive material can be attached with the radially outer wall of the tip cap
Non Gaussian extrema counts for CMB maps
In the context of the geometrical analysis of weakly non Gaussian CMB maps,
the 2D differential extrema counts as functions of the excursion set threshold
is derived from the full moments expansion of the joint probability
distribution of an isotropic random field, its gradient and invariants of the
Hessian. Analytic expressions for these counts are given to second order in the
non Gaussian correction, while a Monte Carlo method to compute them to
arbitrary order is presented. Matching count statistics to these estimators is
illustrated on fiducial non-Gaussian "Planck" data.Comment: 4 pages, 1 figur
Un-reduction
This paper provides a full geometric development of a new technique called
un-reduction, for dealing with dynamics and optimal control problems posed on
spaces that are unwieldy for numerical implementation. The technique, which was
originally concieved for an application to image dynamics, uses Lagrangian
reduction by symmetry in reverse. A deeper understanding of un-reduction leads
to new developments in image matching which serve to illustrate the
mathematical power of the technique.Comment: 25 pages, revised versio
Color Evaporation and Elastic Photoproduction at DESY HERA
The diffractive photoproduction of vector mesons is usually described
considering the two-gluon (Pomeron) exchange, non-diagonal parton distributions
and the contribution of the real part to the cross section. In this letter we
analyze the diffractive photoproduction of the at HERA using an
alternative model, the Color Evaporation Model (CEM), where the cross section
is simply determined by the boson-gluon cross section and an assumption for the
production of the colorless state. We verify that, similarly to the
case, the HERA data for this process can be well described by the CEM.
Moreover, we propose the analyzes of the ratio to discriminate between the distinct approaches.Comment: 7 pages, 3 figures, accepted for publication in PRD (Brief Reports
Molecular theory of elastic constants of liquid crystals. III. Application to smectic phases with tilted orientational order
Using the density functional formalism we derive expression for the
distortion free energy for systems with continuous broken symmetry and use it
to derive expression for the elastic constants of smectic phases in which
director is tilted with respect to the smectic layer normal. As in the previous
papers of the series (Phys. Rev. A {\bf 45}, 974 (1992), E {\bf 49}, 501,
(1994)) the expressions for the elastic constants are written in terms of order
and structural parameters. The structural parameters involve the generalised
spherical harmonic coefficients of the direct pair correlation function of an
effective isotropic liquid. The density of this effective isotropic liquid
depends on the nature and amount of ordering present in the system and is
evaluated self- consistently. We estimate the value of elastic constants using
reasonable guess for the order and structural- parameters.Comment: 31 pages; 1 Fig. in GIF format, To be appear in Phys. Rev.
Meson Form Factors and Non-Perturbative Gluon Propagators
The meson (pion and kaon) form factor is calculated in the perturbative
framework with alternative forms for the running coupling constant and the
gluon propagator in the infrared kinematic region. These modified forms are
employed to test the sensibility of the meson form factor to the
nonperturbative contributions. Its is a powerful discriminating quantity and
the results obtained with a particular choice of modified running coupling
constant and gluon propagator have a good agreement with the available data,
for both mesons, indicating the robustness of the method of calculation.
Nevertheless, nonperturbative aspects may be included in the perturbative
framework of calculation of exclusive processes.Comment: 18 pages, 7 figures. Discutions added, clarifing figures. Accepted to
be published in Phys. Rev.
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