5,305 research outputs found
Quantum bit string sealing
Though it was proven that secure quantum sealing of a single classical bit is
impossible in principle, here we propose an unconditionally secure quantum
sealing protocol which seals a classical bit string. Any reader can obtain each
bit of the sealed string with an arbitrarily small error rate, while reading
the string is detectable. The protocol is simple and easy to be implemented.
The possibility of using this protocol to seal a single bit in practical is
also discussed.Comment: Add a discussion on the possibility of sealing a single bit in
practica
Determination of the - mixing angle
We extract - mixing angle and the ratios of decay
constants of light pseudoscalar mesons , and using
recently available BaBar measurements on -photon and -photon
transition form factors and more accurate experimental data for the masses and
two-photon decay widths of the light pseduoscalar mesons.Comment: 5 pages, revtex, no figures, accepted for publication as a Brief
Report in Physical Review
Numerical methods for coupled reconstruction and registration in digital breast tomosynthesis.
Digital Breast Tomosynthesis (DBT) provides an insight into the fine details of normal fibroglandular tissues and abnormal lesions by reconstructing a pseudo-3D image of the breast. In this respect, DBT overcomes a major limitation of conventional X-ray mam- mography by reducing the confounding effects caused by the superposition of breast tissue. In a breast cancer screening or diagnostic context, a radiologist is interested in detecting change, which might be indicative of malignant disease. To help automate this task image registration is required to establish spatial correspondence between time points. Typically, images, such as MRI or CT, are first reconstructed and then registered. This approach can be effective if reconstructing using a complete set of data. However, for ill-posed, limited-angle problems such as DBT, estimating the deformation is com- plicated by the significant artefacts associated with the reconstruction, leading to severe inaccuracies in the registration. This paper presents a mathematical framework, which couples the two tasks and jointly estimates both image intensities and the parameters of a transformation. Under this framework, we compare an iterative method and a simultaneous method, both of which tackle the problem of comparing DBT data by combining reconstruction of a pair of temporal volumes with their registration. We evaluate our methods using various computational digital phantoms, uncom- pressed breast MR images, and in-vivo DBT simulations. Firstly, we compare both iter- ative and simultaneous methods to the conventional, sequential method using an affine transformation model. We show that jointly estimating image intensities and parametric transformations gives superior results with respect to reconstruction fidelity and regis- tration accuracy. Also, we incorporate a non-rigid B-spline transformation model into our simultaneous method. The results demonstrate a visually plausible recovery of the deformation with preservation of the reconstruction fidelity
Consistency of field-theoretical and kinetic calculations of viscous transport coefficients for a relativistic fluid
The transport coefficients of causal relativistic dissipative fluid dynamics
are calculated both in a field-theoretical and a kinetic approach. We find that
the results from the traditional kinetic calculation by Israel and Stewart are
modified. The new expressions for the viscous transport coefficients agree with
the results obtained in the field-theoretical approach when the contributions
from pair creation and annihilation are neglected.Comment: 4 pages, 2 figure
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