45,432 research outputs found
Microwave induced elastic deformation of a metallic thin film
The microwave induced elastic deformation of a metallic thin film is computed
numerically and we found that the deformation can be significantly enhanced at
resonance. We show that an analytical transmission line model can reproduce the
numerical results almost quantitatively and at the same time reveal the
underlying physics.Comment: 8 pages,3 figure
Automatic detection and classification of nasopharyngeal carcinoma on PET/CT with support vector machine
Purpose: Positron emission tomography/computed tomography (PET/CT) has established values for imaging of head and neck cancers, including the nasopharyngeal carcinoma (NPC), utilizing both morphologic and functional information. In this paper, we introduce a computerized system for automatic detection of NPC, targeting both the primary tumor and regional nodal metastasis, on PET/CT. Methods: Candidate lesions were extracted based on the features from both PET and CT images and a priori knowledge of anatomical features and subsequently classified by a support vector machine algorithm. The system was validated with 25 PET/CT examinations from 10 patients suffering from NPC. Lesions manually contoured by experienced radiologists were used as the gold standard. Results: Results showed that the system successfully identified all 53 hypermetabolic lesions larger than 1 cm in size and excluded normal physiological uptake in brown fat, muscles, bone marrow, brain, and salivary glands. Conclusion: The system combined both imaging features and a priori clinical knowledge for classification between pathological and physiological uptake. Preliminary results showed that the system was highly accurate and promising for adoption in clinical use. © The Author(s) 2011.published_or_final_versionSpringer Open Choice, 25 May 201
Exact Solutions of Relativistic Two-Body Motion in Lineal Gravity
We develop the canonical formalism for a system of bodies in lineal
gravity and obtain exact solutions to the equations of motion for N=2. The
determining equation of the Hamiltonian is derived in the form of a
transcendental equation, which leads to the exact Hamiltonian to infinite order
of the gravitational coupling constant. In the equal mass case explicit
expressions of the trajectories of the particles are given as the functions of
the proper time, which show characteristic features of the motion depending on
the strength of gravity (mass) and the magnitude and sign of the cosmological
constant. As expected, we find that a positive cosmological constant has a
repulsive effect on the motion, while a negative one has an attractive effect.
However, some surprising features emerge that are absent for vanishing
cosmological constant. For a certain range of the negative cosmological
constant the motion shows a double maximum behavior as a combined result of an
induced momentum-dependent cosmological potential and the gravitational
attraction between the particles. For a positive cosmological constant, not
only bounded motions but also unbounded ones are realized. The change of the
metric along the movement of the particles is also exactly derived.Comment: 37 pages, Latex, 24 figure
Genetic algorithm supported by graphical processing unit improves the exploration of effective connectivity in functional brain imaging
published_or_final_versio
Exact Solution for the Metric and the Motion of Two Bodies in (1+1) Dimensional Gravity
We present the exact solution of two-body motion in (1+1) dimensional dilaton
gravity by solving the constraint equations in the canonical formalism. The
determining equation of the Hamiltonian is derived in a transcendental form and
the Hamiltonian is expressed for the system of two identical particles in terms
of the Lambert function. The function has two real branches which join
smoothly onto each other and the Hamiltonian on the principal branch reduces to
the Newtonian limit for small coupling constant. On the other branch the
Hamiltonian yields a new set of motions which can not be understood as
relativistically correcting the Newtonian motion. The explicit trajectory in
the phase space is illustrated for various values of the energy. The
analysis is extended to the case of unequal masses. The full expression of
metric tensor is given and the consistency between the solution of the metric
and the equations of motion is rigorously proved.Comment: 34 pages, LaTeX, 16 figure
Genetic algorithm supported by graphical processing unit improves the exploration of effective connectivity in functional brain imaging
published_or_final_versio
Lateral Optical Force On Chiral Particles Near a Surface
Light can exert radiation pressure on any object it encounters and that
resulting optical force can be used to manipulate particles. It is commonly
assumed that light should move a particle forward and indeed an incident plane
wave with a photon momentum hk can only push any particle, independent of its
properties, in the direction of k. Here we demonstrate using full-wave
simulations that an anomalous lateral force can be induced in a direction
perpendicular to that of the incident photon momentum if a chiral particle is
placed above a substrate that does not break any left-right symmetry.
Analytical theory shows that the lateral force emerges from the coupling
between structural chirality (the handedness of the chiral particle) and the
light reflected from the substrate surface. Such coupling induces a sideway
force that pushes chiral particles with opposite handedness in opposite
directions.Comment: 30 pages, 9 figure
ADI splitting schemes for a fourth-order nonlinear partial differential equation from image processing
We present directional operator splitting schemes for the numerical solution of a fourth-order, nonlinear partial differential evolution equation which arises in image processing. This equation constitutes the H−1-gradient flow of the total variation and represents a prototype of higher-order equations of similar type which are popular in imaging for denoising, deblurring and inpainting problems. The efficient numerical solution of this equation is very challenging due to the stiffness of most numerical schemes. We show that the combination of directional splitting schemes with implicit time-stepping provides a stable and computationally cheap numerical realisation of the equation
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