6,962 research outputs found
Choosing an allograft or autograft in orthopedic surgeries for athletes
Athletes and their doctors have the choice of using an allograft or autograft in reconstruction surgeries. The purpose of this study is to see if there is a difference in the healing mechanism and surgical outcome in using an allograft or autograft during orthopedic surgical procedures, as well as to analyze graft rejection and disease transmission through donor tissue.
Doctors and athletic trainers were interviewed in order to learn about the healing mechanisms and advantages and disadvantages of allografts and autografts in order to conclude if one was better than the other. College level athletes on different sports teams were given a questionnaire that asked questions on the surgical procedure they got and whether or not the surgeon used an allograft or autograft. Specific questions relating to recovery time, stability, and overall function of the area of surgery were asked in order to analyze the outcome. The subjects were screened by choosing athletes with the same surgical reconstruction except one using an allograft and one using an autograft. The questions relating to the outcome of the surgery were compared in order to see if one produced a better outcome over the other. Athletes were found to have better success with autograft as predicted by doctors
A rare case of leiomyoma of the bladder
Bladder leiomyoma is a benign tumour of the bladder and constitute <0.5% of all bladder tumors. We report a clinical case of a 51‑year‑old female who presented with with symptomatic bladder leiomyoma. An ultrasound examination showed well-defined bladder leiomyoma in the right posterior bladder wall, which was excised through a transurethral resection. The pathologic diagnosis was bladder leiomyoma
Open and / or laparoscopic surgical treatment of liver hydatic cysts
Hydatid disease is a severe parasitic disease with a widely ranging distribution. In the human being the liver is the most frequent organ affected. 1 The treatment should be individualized to the morphology, size, number and location of the cysts, that is why a variety of surgical operations have been advocated from complete resection like total pericystectomy or partial hepatectomy to laparoscopy to a minimally invasive procedures like percutaneous aspiration of cysts to conservative drug therapy. 3-4 This study compares laparoscopic versus open management of the hydatid cyst of liver the surgical approach to liver echinococcosis is still a controversial issue and shows our results of surgical treatment of liver hydatid cysts during a 3-years period
Stochastic background of gravitational waves "tuned" by gravity
The cosmological background of gravitational waves can be tuned by Extended
Theories of Gravity. In particular, it can be shown that assuming a generic
function of the Ricci scalar gives a parametric approach to control
the evolution and the production mechanism of gravitational waves in the early
Universe.Comment: 5 pages, to appear in the Proceedings of the 3rd Stueckelberg
Workshop, July 2008, Pescara - Ital
Scattering from Solutions of Star Polymers
We calculate the scattering intensity of dilute and semi-dilute solutions of
star polymers. The star conformation is described by a model introduced by
Daoud and Cotton. In this model, a single star is regarded as a spherical
region of a semi-dilute polymer solution with a local, position dependent
screening length. For high enough concentrations, the outer sections of the
arms overlap and build a semi-dilute solution (a sea of blobs) where the inner
parts of the actual stars are embedded. The scattering function is evaluated
following a method introduced by Auvray and de Gennes. In the dilute regime
there are three regions in the scattering function: the Guinier region (low
wave vectors, q R << 1) from where the radius of the star can be extracted; the
intermediate region (1 << q R << f^(2/5)) that carries the signature of the
form factor of a star with f arms: I(q) ~ q^(-10/3); and a high wavevector zone
(q R >> f^(2/5)) where the local swollen structure of the polymers gives rise
to the usual q^(-5/3) decay. In the semi-dilute regime the different stars
interact strongly, and the scattered intensity acquires two new features: a
liquid peak that develops at a reciprocal position corresponding to the
star-star distances; and a new large wavevector contribution of the form
q^(-5/3) originating from the sea of blobs.Comment: REVTeX, 12 pages, 4 eps figure
Multi-rendezvous Spacecraft Trajectory Optimization with Beam P-ACO
The design of spacecraft trajectories for missions visiting multiple
celestial bodies is here framed as a multi-objective bilevel optimization
problem. A comparative study is performed to assess the performance of
different Beam Search algorithms at tackling the combinatorial problem of
finding the ideal sequence of bodies. Special focus is placed on the
development of a new hybridization between Beam Search and the Population-based
Ant Colony Optimization algorithm. An experimental evaluation shows all
algorithms achieving exceptional performance on a hard benchmark problem. It is
found that a properly tuned deterministic Beam Search always outperforms the
remaining variants. Beam P-ACO, however, demonstrates lower parameter
sensitivity, while offering superior worst-case performance. Being an anytime
algorithm, it is then found to be the preferable choice for certain practical
applications.Comment: Code available at https://github.com/lfsimoes/beam_paco__gtoc
Designing optimal low-thrust gravity-assist trajectories using space-pruning and a multi-objective approach
A multi-objective problem is addressed consisting of finding optimal low-thrust gravity-assist trajectories for interplanetary and orbital transfers. For this, recently developed pruning techniques for incremental search space reduction - which will be extended for the current situation - in combination with subdivision techniques for the approximation of the entire solution set, the so-called Pareto set, are used. Subdivision techniques are particularly promising for the numerical treatment of these multi-objective design problems since they are characterized (amongst others) by highly disconnected feasible domains, which can easily be handled by these set oriented methods. The complexity of the novel pruning techniques is analysed, and finally the usefulness of the novel approach is demonstrated by showing some numerical results for two realistic cases
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