Field-theoretical approach to particle oscillations in absorbing matter

The $ab$ oscillations in absorbing matter are considered. The standard model based on optical potential does not describe the total $ab$ transition probability as well as the channel corresponding to absorption of the $b$-particle. We calculate directly the off-diagonal matrix element in the framework of field-theoretical approach. Contrary to one-particle model, the final state absorption does not tend to suppress the channels mentioned above or, similarly, calculation with hermitian Hamiltonian leads to increase the corresponding values. The model reproduces all the results on the particle oscillations, however it is oriented to the description of the above-mentioned channels. Also we touch on the problem of infrared singularities. The approach under study is infrared-free.Comment: 27 pages, 8 figure

Critical Examination of the "Field-Theoretical Approach" to the Neutron-Antineutron Oscillations in Nuclei

We demonstrate that so called "infrared divergences" which have been discussed in some publications during several years, do not appear within the correct treatment of analytical properties of the transition amplitudes, in particular, of the second order pole structure of the amplitudes describing the $n - \bar n$ transition in nuclei. Explicit calculation with the help of the Feynman diagram technique shows that the neutron-antineutron oscillations are strongly suppressed in the deuteron, as well as in heavier nuclei, in comparison with the oscillations in vacuum. General advantages and some difficulties of the field theoretical methods applied in nuclear theory are reminded for the particular example of the parity violating $np\to d\gamma$ capture amplitude.Comment: 15 pages, 4 figures; prepared for Eur.Phys.J.

Tubulohelical membrane arrays: From the initial observation to the elucidation of nanophysical properties and cellular function

Lipids undergo self-assembly to form ordered nonlamellar, nanoperiodic arrays both in vitro and in vivo. While engineering of such membrane arrays for technical devices is envisaged, we know little about their cellular function. Do they represent building blocks of an inherent cellular nanotechnology? Prospects for answering this question could be improved if the nanophysical properties of the membrane arrays could be studied in the context of specific cellular functions. Therefore, we draw attention to exceptional complex membrane arrays found in the renal epithelial cell line PtK2 that could provide perfect conditions for both biophysical and cell functional studies. The so-called tubulohelical membrane arrays (TUHMAs) combine nanoperiodicity of lipid membranes with that of helix-like proteinaceous core structures. Strikingly, they show several characteristics of dynamic, microtubule-associated single organelles. Our initial data indicate that TUHMA formation occurs in the depth of the cytoplasm under participation of cytoplasmic nucleoporins. Once matured, they may fuse with the nuclear membrane in polarized positions, either perpendicularly or in parallel to the nucleus. As a starting point for the initiation of functional studies we found a connection between TUHMAs and primary cilia, indicated by immunolabeling patterns of detyrosynated tubulin and cytoplasmic nucleoporins. We discuss these observations in the context of the ciliary cycle and of the specific requirement of ciliated renal epithelial cells for oriented cell division. Finally, we raise the question of whether putative nanooptical properties of TUHMAs could serve for communicating orientation between dividing cells

ALL-SKY CAMERAS FOR OBSERVATION AND INVESTIGATION OF VARIABLE STARS AND METEOR SHOWERS

This paper studies the capabilities of the all-sky weather (meteorological) cameras in investigation of bright variable stars and determination of apparent radiants of meteor showers. This paper studies the capabilities of the all-sky weather (meteorological) cameras in investigation of bright variable stars and determination of apparent radiants of meteor showers.