750 research outputs found
Tangent bundle geometry from dynamics: application to the Kepler problem
In this paper we consider a manifold with a dynamical vector field and
inquire about the possible tangent bundle structures which would turn the
starting vector field into a second order one. The analysis is restricted to
manifolds which are diffeomorphic with affine spaces. In particular, we
consider the problem in connection with conformal vector fields of second order
and apply the procedure to vector fields conformally related with the harmonic
oscillator (f-oscillators) . We select one which covers the vector field
describing the Kepler problem.Comment: 17 pages, 2 figure
Tensorial dynamics on the space of quantum states
A geometric description of the space of states of a finite-dimensional
quantum system and of the Markovian evolution associated with the
Kossakowski-Lindblad operator is presented. This geometric setting is based on
two composition laws on the space of observables defined by a pair of
contravariant tensor fields. The first one is a Poisson tensor field that
encodes the commutator product and allows us to develop a Hamiltonian
mechanics. The other tensor field is symmetric, encodes the Jordan product and
provides the variances and covariances of measures associated with the
observables. This tensorial formulation of quantum systems is able to describe,
in a natural way, the Markovian dynamical evolution as a vector field on the
space of states. Therefore, it is possible to consider dynamical effects on
non-linear physical quantities, such as entropies, purity and concurrence. In
particular, in this work the tensorial formulation is used to consider the
dynamical evolution of the symmetric and skew-symmetric tensors and to read off
the corresponding limits as giving rise to a contraction of the initial Jordan
and Lie products.Comment: 31 pages, 2 figures. Minor correction
Preoperative digital three-dimensional planning for rhinoplasty
BACKGROUND: This report describes preoperative digital planning for rhinoplasty using a new three-dimensional (3D) radiologic viewer that allows both patients and surgeons to visualize on a common monitor the 3D real aspect of the nose in its inner and outer sides.
METHODS: In the period 2002 to 2008, 210 patients underwent rhinoplasty procedures in the authors' clinic. The patients were randomly divided into three groups according to the type of preoperative planning used: photos only, a simulated result by Adobe Photoshop, or the 3D radiologic viewer. The parameters evaluated included the number of patients that underwent surgery after the first consultation, the number of patients who asked for a reintervention, patient satisfaction (according to a test given to the patients 12 months postoperatively), the surgical time required for a functional intervention, and the improvement in nasal function by postoperative rhinomanometry and subjective evaluation.
RESULTS: Computer-aided technologies led to a higher number of patients deciding to undergo a rhinoplasty. Simulation of the postoperative results was not as useful in the postoperative period due to the higher number of reintervention requests.
CONCLUSION: The patients undergoing rhinoplasties preferred new technologies in the preoperative period. The advantages of using the 3D radiologic viewer included improved preoperative planning, reduction in intraoperative stress, a higher number of patients undergoing surgery, reduction in postoperative surgical corrections, reduction in surgical time for the functional intervention, a higher rate of improvement in nasal function, a higher percentage of postoperative satisfaction, and reduced costs
Hábitos de entrenamiento y lesiones deportivas en la selección murciana de baloncesto 2007
Assessing the Left Ventricular Systolic Function at the Bedside: The Role of Transpulmonary Thermodilution-Derived Indices
Evaluating the systolic function of the left ventricle (LV) is important in the hemodynamic management of the critically ill patients with circulatory failure. Echocardiography is considered the standard monitor for estimating the LV function at the bedside in the intensive care unit. However, it requires a trained operator and is not a real-time monitoring tool. For monitoring of the systolic function, the pulmonary artery catheter has been the gold standard for a long time. However, now there are alternatives to this device, with transpulmonary thermodilution being one of them. This paper provides an overview of the usefulness of the transpulmonary thermodilution-derived indices for assessing systolic function at the bedside
Characterization of the Hamamatsu S8664 Avalanche Photodiode for X-Ray and VUV-light detection
We present the first operation of the Avalanche Photodiode (APD) from
Hamamatsu to xenon scintillation light and to direct X-rays of 22.1 keV and 5.9
keV. A large non-linear response was observed for the direct X-ray detection.
At 415 V APD bias voltage it was of about 30 % for 22.1 keV and about 45 % for
5.9 keV. The quantum efficiency for 172 nm photons has been measured to be 69
+/- 15 %.Comment: 11 pages, 3 figures, submitted to Elsevie
P246 PREVALENCE AND VIRAL LOAD OF PARVOVIRUS B19, VARICELLA-ZOSTER VIRUS, AND HUMAN HERPESVIRUS-6 IN MESENCHYMAL STEM CELLS OF PATIENTS WITH OSTEOARTHRITIS
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