Student-Centered Rehabilitation Medicine Research Elective

Purpose: To provide an opportunity for medical students to participate in rehabilitation research and allows the investigator to develop a database of the characteristics of the medical students choosing this elective. [See PDF for complete abstract

Photon polarization and Wigner's little group

To discuss one-photon polarization states we find an explicit form of the Wigner's little group element in the massless case for arbitrary Lorentz transformation. As is well known, when analyzing the transformation properties of the physical states, only the value of the phase factor is relevant. We show that this phase factor depends only on the direction of the momentum $\vec{k}/|\vec{k}|$ and does not depend on the frequency $k^0$. Finally, we use this observation to discuss the transformation properties of the linearly polarized photons and the corresponding reduced density matrix. We find that they transform properly under Lorentz group.Comment: Version published in Phys. Rev. A, few typos correcte

Einstein-Podolsky-Rosen correlations of Dirac particles - quantum field theory approach

We calculate correlation function in the Einstein--Podolsky--Rosen type of experiment with massive relativistic Dirac particles in the framework of the quantum field theory formalism. We perform our calculations for states which are physically interesting and transforms covariantly under the full Lorentz group action, i.e. for pseudoscalar and vector state.Comment: 9 pages, 2 figures. Published versio

Numerical and experimental analysis of innovative support system of belt conveyor

The article processes an issue of the strength of a support system of a belt conveyor applying the numerical and experimental analysis approach. The support system of a belt conveyor is during the operation exposed to high impact forces due to the impact of the foreign objects. The methodology of the numerical analysis is based on the finite element modelling and according to the experimental analysis the boundary conditions are estimated. The results obtained using the numerical analyses are identical to the results from the experimental analysis. Maximal damage of the support system of a belt conveyor is estimated and according to the proposed methodology verified by the comparison of the experimental and numerical results, the design and optimization of the support system for the practical operation can be performed

Helicity correlations of vector bosons

We calculate the helicity and polarization correlation functions in the Einstein-Podolsky-Rosen-type experiments with relativistic vector bosons. We show that the linear polarization correlation function in the appriopriately chosen state in the massless limit is the same as the correlation function in the scalar two-photon state. We show also that the polarization correlation function violate the Clauser-Horne-Shimony-Holt inequality and that the degree of this violation can increase with the particle momentum.Comment: 8 pages, 3 figure

Urinary bladder diverticulum as an unusual content of the inguinal canal

The inguinal urinary bladder hernia is a rare pathology observed mostly in males. A new case of asymptomatic reducible acquired inguinal hernia was revealed in a 54-year-old male during computed tomography (CT) undertaken for oncological follow-up. The right nephrectomy was previously performed due to clear cell carcinoma. The hernia was not visible on the CT 6 months before and on ultrasound performed after voiding. Slight herniation with a wide invagination of transversalis fascia but with empty bladder was seen on CT 4 months after the initial detection of hernia

Effect of growth pressure on coalescence thickness and crystal quality of GaN deposited on 4H-SiC

Cataloged from PDF version of article.The influence of growth pressure on the coalescence thickness and the crystal quality of GaN deposited on 4H-SiC by low pressure metalorganic vapor phase epitaxy was studied. It was shown that growth pressure has an impact on the surface roughness of epilayers and their crystal quality. GaN coalescence thicknesses were determined for the investigated growth pressures. The GaN layers were characterized by AFM and HRXRD measurements. HEMT structures were also fabricated and characterized. Among the growth pressures studied, 50, 125 and 200 mbar, 200 mbar was found to be most suitable for GaN/SiC epitaxy. (C) 2010 Elsevier B.V. All rights reserved

Unstable particles as open quantum systems

We present the probability preserving description of the decaying particle within the framework of quantum mechanics of open systems taking into account the superselection rule prohibiting the superposition of the particle and vacuum. In our approach the evolution of the system is given by a family of completely positive trace preserving maps forming one-parameter dynamical semigroup. We give the Kraus representation for the general evolution of such systems which allows one to write the evolution for systems with two or more particles. Moreover, we show that the decay of the particle can be regarded as a Markov process by finding explicitly the master equation in the Lindblad form. We also show that there are remarkable restrictions on the possible strength of decoherence.Comment: 11 pp, 2 figs (published version

Lorentz-covariant, unitary evolution of a relativistic Majorana qubit

We formulate a covariant description of a relativistic qubit identified with an irreducible set of quantum spin states of a Majorana particle with a sharp momentum. We treat the particle’s four-momentum as an external parameter. We show that it is possible to define an interesting time evolution of the spin density matrix of such a qubit. This evolution is manifestly Lorentz covariant in the bispinor representation and unitary in the spin representation. Moreover, during this evolution the Majorana particle undergoes an uniformly accelerated motion. We classify possible types of such motions, and finally we illustrate the behaviour of the polarization vector of the Majorana qubit during the evolution in some special cases