Density dependence of resonance broadening and shadowing effects in nuclear photoabsorption

Medium effects as a function of the mass number $A$ are studied in the total photonuclear cross section from the $\Delta$-resonance region up to the region where shadowing effects are known to exist. A consistent picture is obtained by simply assuming a density dependence of the different mechanisms of resonance broadening and shadowing. The $\Delta$-mass shift is found to increase with $A$.Comment: 7 pages, LaTeX, 2 figures available from the author

Quantum parallel dense coding of optical images

We propose quantum dense coding protocol for optical images. This protocol extends the earlier proposed dense coding scheme for continuous variables [S.L.Braunstein and H.J.Kimble, Phys.Rev.A 61, 042302 (2000)] to an essentially multimode in space and time optical quantum communication channel. This new scheme allows, in particular, for parallel dense coding of non-stationary optical images. Similar to some other quantum dense coding protocols, our scheme exploits the possibility of sending a classical message through only one of the two entangled spatially-multimode beams, using the other one as a reference system. We evaluate the Shannon mutual information for our protocol and find that it is superior to the standard quantum limit. Finally, we show how to optimize the performance of our scheme as a function of the spatio-temporal parameters of the multimode entangled light and of the input images.Comment: 15 pages, 4 figures, RevTeX4. Submitted to the Special Issue on Quantum Imaging in Journal of Modern Optic

Feynman Diagrams and Differential Equations

We review in a pedagogical way the method of differential equations for the evaluation of D-dimensionally regulated Feynman integrals. After dealing with the general features of the technique, we discuss its application in the context of one- and two-loop corrections to the photon propagator in QED, by computing the Vacuum Polarization tensor exactly in D. Finally, we treat two cases of less trivial differential equations, respectively associated to a two-loop three-point, and a four-loop two-point integral. These two examples are the playgrounds for showing more technical aspects about: Laurent expansion of the differential equations in D (around D=4); the choice of the boundary conditions; and the link among differential and difference equations for Feynman integrals.Comment: invited review article from Int. J. Mod. Phys.

Особенности эволюции химического состава фосфатов как отражение многофазного становления щелочно-карбонатитовой флюидо-эксплозивной системы Среднего Тимана

he alkaline-carbonate fluid-explosive structure in the Middle Timan includes carbonatites, carbonatized fluidexplosive dikes, and fenitized terrigenous-carbonate rocks of the Riphean. Phosphates, represented by monazite and apatite, are formed in all rocks. The chemical composition of the minerals testifies to the multiphase formation of this structure and a single source of fluids involved in its formation.В щелочно-карбонатитовую флюидо-эксплозивную систему на Среднем Тимане входят карбонатиты, карбонатизированные флюидо-экспозивные дайки и фенитизированные терригено-карбонатные породы рифея. Во всех породах кристаллизуются фосфаты, представленные монацитом и апатитом. Химический состав минералов свидетельствует о многофазности становления данной системы и едином источнике флюидов, участвовавших в ее формировании

Обобщенный опыт изучения и диагностики конвергентных пород на примере карбонатизированных флюидоэксплозивных ультрамафитов дайкового комплекса Среднего Тимана

Fluid-explosive rocks of the dike complex are identified in the Middle Timan. The rocks have convergent properties due to a combination of explosive and metasomatic processes. The study of the petrographic features of the rocks revealed their explosive nature. Further study of the chemical composition of rock-forming minerals established the source of the mantle material and the paragenetic relationship with carbonatite magmatism. The fluid-explosive rocks of the dyke complex have a long-term multistage formation history. The fluids caused fenitization of the host strata and its disintegration. Solid-gas material of the mantle-crustal compound fills the cracks. At the last stage of formation of fluid-explosive rocks, the rare-metal, rare-earth, and sulfide mineralization took place.На Среднем Тимане выделены дайковые флюидоэксплозивные породы с конвергентными свойствами за счет сочетания эксплозивных и метасоматических процессов. Изучение петрографических особенностей пород выявило их эксплозивную природу, а исследование химического состава породообразующих минералов установило источник мантийного материала и парагенетическую связь с карбонатитовым магматизмом. Флюидоэксплозивные породы дайкового комплекса связаны с фенитизацией вмещающей толщи с последующей ее дезинтеграцией и заполнением трещин твердогазовым материалом смешанного мантийно-корового состава. На последнем этапе становления флюидоэксплозивных пород за счет карбонатизации проявляются редкометалльно-редкоземельная и сульфидная минерализации

Neutron-antineutron Oscillations in the Trapping Box

We have reexamined the problem of $n-\bar n$ oscillations for ultra-cold neutrons (UCN) confined within a trap. We have shown that the growth of the $\bar n$ component with time is to a decent accuracy given by $P(\bar n)= \epsilon^2_{n\bar n} t_Lt,$ where $\epsilon_{n\bar n}$ is the mixing parameter, $t_L\sim 1$ sec in the neutron propagation time between subsequent collisions with the trap walls. Possible corrections to this law and open questions are discussed.Comment: 11 pages, LaTeX2

Threshold J/ψ−J/\psi- production in nucleon-nucleon collisions

We analyze $J/\psi-$ production in nucleon-nucleon collisions near threshold in the framework of a general model independent formalism, which can be applied to any reaction $N+N\to N+N+V^0$, where $V^0=\omega$, $\phi$, or $J/\psi$. Such reactions show large isotopic effects: a large difference for $pp$- and $pn$-collisions, which is due to the different spin structure of the corresponding matrix elements. The analysis of the spin structure and of the polarization observables is based on symmetry properties of the strong interaction. Using existing experimental data on the different decays of $J/\psi-$meson, we suggest a model for $N+N\to N+N+J/\psi$, based on $t-$channel $\eta+\pi$-exchanges. We predict polarization phenomena for the $n+p\to n+p+J/\psi$-reaction and the ratio of cross sections for $np$ and $pp$-collisions. For the processes $\eta(\pi)+N\to N+J/\psi$ we apply two different approaches: vector meson exchange and local four-particle interaction. In both cases we find larger $J/\psi$-production in $np$-collisions, with respect to $pp$-collisions.Comment: 17 pages, 6 figure

Experience in the use of docosahexaenoic acid (BrudiPlus) in patients with increased sperm DNA fragmentation index in Acad. V.I. Kulakov Research Center for Obstetrics, Gynecology and Perinatology

Male factor is the reason of infertility in almost half of marriages. Infertile men have the percentage of sperm with violations of DNA integrity of over 30 %; with that, healthy fertile men have that indicator of less than 15 %. Understanding of importance of damages of sperm DNA is growing with distribution ofauxiliary reproductive technologies. As of today, these consequences have not been studies yet, and the therapeutic effect of intake of antioxidants has not direct correlation with the sperm DNA fragmentation level. Docosahexaenoic acid is one of the most valuable omega-3 polyunsaturated fatty acids for human health. Docosahexaenoic acid is the main component of the brain gray matter, retina, testes, and sperm cell membranes. In connection with that, a study was held the purpose of which was to assess the effect of the nutraceutical enzymatic docosahexaenoic acid triglyceride (BrudiPlus) in high concentrations on damaged sperm DNA of patients with idiopathic pathozoospermia. 40 patients with idiopathic pathozoospermia and the level of DNA fragmentation over the statutory value took part in this study. The following positive results were received: intake of BrudiPlus allowed decreasing sperm DNA damages and improving of antioxidant system of sperm