Rotating black holes in dilatonic Einstein-Gauss-Bonnet theory

We construct generalizations of the Kerr black holes by including higher-curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. We show that the domain of existence of these Einstein-Gauss-Bonnet-dilaton (EGBD) black holes is bounded by the Kerr black holes, the critical EGBD black holes, and the singular extremal EGBD solutions. The angular momentum of the EGBD black holes can exceed the Kerr bound. The EGBD black holes satisfy a generalized Smarr relation. We also compare their innermost stable circular orbits with those of the Kerr black holes and show the existence of differences which might be observable in astrophysical systems.     

Spinodal Curve for the System Water + 1-Pentanol + 1-Propanol at 25 °C

The liquid–liquid equilibrium data at 25 °C of the system water–1-pentanol–1-propanol, that present a I type solubility gap, have been used to calculate the spinodal curve of this system through the use of the Wheeler–Widom model. As in the case of the water–chloroform–acetic acid system, analyzed with the same model in the past, a local fitting method has been necessary. A procedure based on the experimental position of the plait point was used to obtain the single spinodal points. The relative positions of binodal and spinodal curves indicate the presence of a large metastable area in the alcoholic-rich region.     

Integration of an Equilibrium System in an Enhanced Theory of Bending of Elastic Plates

The complete integral of the system of partial differential equations governing the equilibrium bending of elastic plates with transverse shear deformation and transverse normal strain is constructed by means of complex variable methods. The process helps to elucidate the physical meaning of certain analytic constraints imposed on the asymptotic behavior of the solutions and shows that in the case of an infinite plate, any analytic solution has finite energy if and only if the bending and twisting moments, the transverse shear force, the displacements in vertical planes, and two other characteristic quantities vanish at infinity. An example is discussed to illustrate the theory.     

Channeling of Neutrons in the Potential Well of a Planar Waveguide

The channeling of neutrons in a three-layer planar waveguide with a neutron-optical potential well is studied. Neutrons incident on a sample surface, which propagate in a middle layer and escape from the waveguide end in the form of a narrow divergent beam, are detected. The decay parameter of a neutron wave inside the waveguide is measured as a function of the potential well depth. Experimental results are compared with a theory.     

On fluid-structure interaction in transonic wind tunnels

This paper studies the interaction (influence) of perforated walls of transonic wind tunnels in two-dimensional investigations which employ the generalized method for solving Dirichlets problem formulated for the rectangle of the transonic wind tunnel work section. The algorithm has been applied to the aerodynamic experimental results from investigations of NACA 0012 airfoil obtained at the VTI – Aeronautical Institute and the Faculty of Mechanical Engineering in Belgrade to demonstrate in two-dimensional investigations the appropriateness of the presented advanced algorithm for the calculation of the interference of the transonic wind tunnel wall. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Contribution to the determination of the global minimum time for the brachistochronic motion of a holonomic mechanical system

The problem of the brachistochronic motion of a holonomic scleronomic mechanical system is analyzed. The system moves in an arbitrary field of known potential forces. The problem is formulated as an optimal control task, where generalized speeds are taken as control variables. The problem considered is reduced to solving the corresponding two-point boundary-value problem (TPBVP). In order to determine the global minimal solution of the TPBVP, an appropriate numerical procedure based on the shooting method is presented. The global minimal solution represents the solution with the minimum time of motion. The procedure is illustrated by an example of determining the brachistochronic motion of a disk that performs plane motion in a vertical plane in a homogeneous field of gravity.     

Linkage isomerism in nitrite reduction by cytochrome cd1 nitrite reductase

Nitrite reduction by cytochrome cd(1) nitrite reductase (cd(1)NIR) is currently accepted to involve coordination of the nitrite nitrogen atom to the ferrous d(1) heme. Here, density functional theory results are reported on the previously unexplored O-binding of nitrite to ferrous and ferric cd(1)NIR. Although the N-isomer (nitro) is energetically favored over the O-nitrite (nitrito), even one single strong hydrogen bond may provide the energy required to put the two isomers on level terms. When hydrogen bonding existent at the cd(1)NIR active site is accounted for in the computational model, the O-nitrite isomer is found to spontaneously protonate and thus yield a ferric-hydroxo species, liberating nitric oxide. An O-nitrite ferrous cd(1)NIR complex appears to be an energetically feasible intermediate for nitrite reduction. O-Coordination would offer an advantage since the end product of nitrite reduction would be a ferric-hydroxo/water complex, rather than the more kinetically inert iron-nitrosyl complex implied by the N-nitrite mechanism.     

Review of AdS/CFT Integrability,Chapter V.1: Scattering Amplitudes: A Brief Introduction

Letters in Mathematical Physics - We review current efficient techniques for the construction of multi-leg and multi-loop on-shell scattering amplitudes in supersymmetric gauge theories. Examples...     

Error bound results for convex inequality systems via conjugate duality

The aim of this paper is to implement some new techniques, based on conjugate duality in convex optimization, for proving the existence of global error bounds for convex inequality systems. First of all, we deal with systems described via one convex inequality and extend the achieved results, by making use of a celebrated scalarization function, to convex inequality systems expressed by means of a general vector function. We also propose a second approach for guaranteeing the existence of global error bounds of the latter, which meanwhile sharpens the classical result of Robinson.