Gravity in Brans-Dicke theory with Born-Infeld scalar field and the Pioneer anomaly

In this paper we discuss a model which can be considered as a generalization of the well-known scalar-tensor Brans-Dicke theory. This model possesses an interesting feature: due to Born-Infeld type non-linearity of the scalar field the properties of the interaction between two test bodies depend significantly on their masses. It is shown that the model can be interesting in view of the Pioneer 10, 11 spacecraft anomaly.Comment: 10 pages, 1 figure, partially changed conten

Energy of eigen-modes in magnetohydrodynamic flows of ideal fluids

Analytical expression for energy of eigen-modes in magnetohydrodynamic flows of ideal fluids is obtained. It is shown that the energy of unstable modes is zero, while the energy of stable oscillatory modes (waves) can assume both positive and negative values. Negative energy waves always correspond to non-symmetric eigen-modes -- modes that have a component of wave-vector along the equilibrium velocity. These results suggest that all non-symmetric instabilities in ideal MHD systems with flows are associated with coupling of positive and negative energy waves. As an example the energy of eigen-modes is calculated for incompressible conducting fluid rotating in axial magnetic field.Comment: 10 pages, 3 figure

A non-standard matter distribution in the RS1 model and the coupling constant of the radion

In the zero mode approximation we solve exactly the equations of motion for linearized gravity in the Randall-Sundrum model with a non-standard distribution of matter in the neighbourhood of the negative tension brane. It is shown that the form of this distribution can strongly affect the coupling of the radion to matter. We believe that such a situation can arise in models with a realistic mechanisms of matter localization.Comment: 12 pages, LaTe

Эффективность в цементе и цементном бетоне диспергированной гранитной породы

The paper presents results of investigations on the dispersion (grinding) process in a ball mill and it also shows an effect of dispersed granitic rock (granite screenings of RUPP “Granit”, Brest region) used as a mineral additive on cement properties, hardening kinetics and cement stone strength, morphology of cement hydration products in the presence of the granitic rock. Complex studies including data of X-ray phase and derivatographic analyses have revealed that granitic rock material does not change morphology of new formations these are reaction products obtained due to reaction of binder clinker portion with water. They are identical to those that are formed due to reactions of a no-dosage (clean-bite) binder with it. At the same time it has been established that when 10–20 % of granite screening grinded up to Sud ~ 3000 cm2/g (0.3 m2/g) have been added to cement strength of cement stone is increased by 20–25 %, and the amount of chemically bound water in clinker component of the binder is increased by 10–15 %. The paper has substantiated a hypothesis of the “crystallization centers” effect which is revealed by fractions of grinded screening £0.3 μm (£3000 Å). The fractions constitute an amount of ~15 % of the screening mass. This hypothesis has been proved by the above-mentioned data on the increase in cement stone strength and amount of chemically bound water in their presence when samples are hardened in normal-humid conditions, in water and after steaming. There is also an obvious increase in strength of cement stone on a binder with this additive (in 2–2.5 times in 1–3 days of hardening) under conditions of “inhibition” in cement hydration reactions due to introduction of a chemical additive that is lignosulphonate technical additive in the cement paste with enhanced dosage (0.3 % of the cement mass).Изложены результаты исследований процесса диспергации (помола) в шаровой мельнице и влияния диспергированной гранитной горной породы (гранитных отсевов РУПП «Гранит», Брестская область), применяемой в качестве минеральной добавки, на свойства цемента, кинетику твердения и прочность цементного камня, морфологию продуктов гидратации цемента в ее присутствии. Результатами комплексных исследований, включая данные рентгенофазового и дериватографического анализов, показано, что вещество гранитной породы не изменяет морфологию новообразований – продуктов реакции клинкерной части вяжущего с водой. Они идентичны тем, которые образуются в результате реакций с ней бездобавочного (чистоклинкерного) вяжущего. Одновременно установлено, что при введении в цемент 10–20 % молотого до Sуд ~ 3000 см2/г (0,3 м2/г) гранитного отсева до 20–25 % возрастает прочность цементного камня и увеличивается на 10–15 % количество химически связываемой воды клинкерной составляющей вяжущего. Обосновывается гипотеза эффекта «центров кристаллизации», который проявляют фракции молотого отсева £0,3 мкм (£3000 Å), содержащиеся в количестве ~15 % его массы. Эту гипотезу подтверждают приведенные выше данные о росте прочности цементного камня и количества химически связываемой воды в их присутствии при твердении образцов в нормально-влажностных условиях, в воде и после пропаривания, а также очевидный рост прочности цементного камня на вяжущем с этой добавкой (в 2–2,5 раза в 1–3 сут. твердения) в условиях «торможения» реакций гидратации цемента за счет введения в цементное тесто химической добавки – лигносульфоната технического – в повышенной (0,3 % от массы цемента) дозировке

Quadratic susceptibility and first hyperpolarizability of the complex of Cr(CO)(3) with 2.2 paracyclophane

The peculiarities of chemical bonding and nonlinear optical properties of the complex of Cr(CO)(3) with [2.2]paracyclophane (Cr-pCp) have been studied by a combined experimental-theoretical approach. The Cr-pCp complex exhibits second harmonic generation, the efficiency of which was measured by the powder technique at 1064.2 nm fundamental wavelength and estimated theoretically. The comparison of electronic structure of the Cr-pCp with benzene tricarbonyl chromium analogue has revealed an important role of intraligand charge transfer state in pCp moiety conditioned by a strong transannular interaction between aromatic rings which is responsible for the enhanced molecular hyperpolarizability of Cr-pCp

Effective Lagrangians for physical degrees of freedom in the Randall-Sundrum model

We derive the second variation Lagrangian of the Randall-Sundrum model with two branes, study its gauge invariance and diagonalize it in the unitary gauge. We also show that the effective four-dimensional theory looks different on different branes and calculate the observable mass spectra and the couplings of the physical degrees of freedom of 5-dimensional gravity to matter.Comment: 22 pages, LaTeX, typos correcte

Gauges in the bulk

We present a general framework for nonparallel brane worlds and use it to discuss the nonlinear radion problem. By imposing the Einstein frame as a gauge condition we are able to give the effective action for both Minkowski and (A)dS$_{4}$ branes. In particular we find the nonlinear radion does not disappear in the second Randall-Sundrum model.Comment: LaTeX file of 14 page

Low-energy gluon contributions to the vacuum polarization of heavy quarks

We calculate a correction to the electromagnetic current induced by a heavy quark loop. The contribution of this correction to the vacuum polarization function appears at the O(alpha_s^3) order of perturbation theory and has a qualitatively new feature -- its absorptive part starts at zero energy in contrast to other contributions where the absorptive parts start at the two-particle threshold. Our result imposes a constraint on the order n of the moments used in the heavy-quark sum rules, n<4.Comment: 8 pages in LaTeX, 1 PostScript figure included in the tex

Understanding the effect of sheared flow on microinstabilities

The competition between the drive and stabilization of plasma microinstabilities by sheared flow is investigated, focusing on the ion temperature gradient mode. Using a twisting mode representation in sheared slab geometry, the characteristic equations have been formulated for a dissipative fluid model, developed rigorously from the gyrokinetic equation. They clearly show that perpendicular flow shear convects perturbations along the field at a speed we denote by $Mc_s$ (where $c_s$ is the sound speed), whilst parallel flow shear enters as an instability driving term analogous to the usual temperature and density gradient effects. For sufficiently strong perpendicular flow shear, $M >1$, the propagation of the system characteristics is unidirectional and no unstable eigenmodes may form. Perturbations are swept along the field, to be ultimately dissipated as they are sheared ever more strongly. Numerical studies of the equations also reveal the existence of stable regions when $M < 1$, where the driving terms conflict. However, in both cases transitory perturbations exist, which could attain substantial amplitudes before decaying. Indeed, for $M \gg 1$, they are shown to exponentiate $\sqrt{M}$ times. This may provide a subcritical route to turbulence in tokamaks.Comment: minor revisions; accepted to PPC

Secondary instability in drift wave turbulence as a mechanism for zonal flow and avalanche formation

The article reports on recent developments in the theory of secondary instability in drift-ion temperature gradient turbulence. Specifically, the article explores secondary instability as a mechanism for zonal flow generation, transport barrier dynamics and avalanche formation. These in turn are related to the space-time statistics of the drift wave induced flux, the scaling of transport with collisionality and β, and the spatio-temporal evolution of transport barriers