Galaxy correlations and the BAO in a void universe: structure formation as a test of the Copernican Principle

A suggested solution to the dark energy problem is the void model, where accelerated expansion is replaced by Hubble-scale inhomogeneity. In these models, density perturbations grow on a radially inhomogeneous background. This large scale inhomogeneity distorts the spherical Baryon Acoustic Oscillation feature into an ellipsoid which implies that the bump in the galaxy correlation function occurs at different scales in the radial and transverse correlation functions. We compute these for the first time, under the approximation that curvature gradients do not couple the scalar modes to vector and tensor modes. The radial and transverse correlation functions are very different from those of the concordance model, even when the models have the same average BAO scale. This implies that if void models are fine-tuned to satisfy average BAO data, there is enough extra information in the correlation functions to distinguish a void model from the concordance model. We expect these new features to remain when the full perturbation equations are solved, which means that the radial and transverse galaxy correlation functions can be used as a powerful test of the Copernican Principle.Comment: 12 pages, 8 figures, matches published versio

Subsonic high-angle-of-attack aerodynamic characteristics of a cone and cylinder with triangular cross sections and a cone with a square cross section

Experiments were conducted in the 12-Foot Pressure Wind Tunnel at Ames Research Center on three models with noncircular cross sections: a cone having a square cross section with rounded corners and a cone and cylinder with triangular cross sections and rounded vertices. The cones were tested with both sharp and blunt noses. Surface pressures and force and moment measurements were obtained over an angle of attack range from 30 deg to 90 deg and selected oil-flow experiments were conducted to visualize surface flow patterns. Unit Reynolds numbers ranged from 0.8x1,000,000/m to 13.0x1,000,000/m at a Mach number of 0.25, except for a few low-Reynolds-number runs at a Mach number of 0.17. Pressure data, as well as force data and oil-flow photographs, reveal that the three dimensional flow structure at angles of attack up to 75 deg is very complex and is highly dependent on nose bluntness and Reynolds number. For angles of attack from 75 deg to 90 deg the sectional aerodynamic characteristics are similar to those of a two dimensional cylinder with the same cross section

Photoactivatable organometallic pyridyl ruthenium(II) arene complexes

The synthesis and characterization of a family of piano-stool RuII arene complexes of the type [(η6-arene)Ru(N,N′)(L)][PF6]2, where arene is p-cymene (p-cym), hexamethylbenzene (hmb), or indane (ind), N,N′ is 2,2′-bipyrimidine (bpm), 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione (phendio), or 4,7-diphenyl-1,10-phenanthroline (bathophen), and L is pyridine (Py), 4-methylpyridine (4-MePy), 4-methoxypyridine (4-MeOPy), 4,4′-bipyridine (4,4′-bpy), 4-phenylpyridine (4-PhPy), 4-benzylpyridine (4-BzPy), 1,2,4-triazole (trz), 3-acetylpyridine (3-AcPy), nicotinamide (NA), or methyl nicotinate (MN), are reported, including the X-ray crystal structures of [(η6-p-cym)Ru(bpm)(4-MePy)]2+ (2), [(η6-p-cym)Ru(bpm)(4-BzPy)]2+ (6), [(η6-p-cym)Ru(bpm)(trz)]2+ (7), [(η6-p-cym)Ru(phen)(Py)]2+ (10), and [(η6-ind)Ru(bpy)(Py)]2+ (13). These complexes can selectively photodissociate the monodentate ligand (L) when excited with UVA or white light, allowing strict control of the formation of the reactive aqua species [(η6-arene)Ru(N,N′)(OH2)]2+ that otherwise would not form in the dark. The photoproducts were characterized by UV–vis absorption and 1H NMR spectroscopy. DFT and TD-DFT calculations were employed to characterize the excited states and to obtain information on the photochemistry of the complexes. All the RuII pyridine complexes follow a relatively similar photochemical L-ligand dissociation mechanism, likely to occur from a series of 3MC triplet states with dissociative character. The photochemical process proved to be much more efficient when UVA-range irradiation was used. More strikingly, light activation was used to phototrigger binding of these potential anticancer agents with discriminating preference toward 9-ethylguanine (9-EtG) over 9-ethyladenine (9-EtA). Calf thymus (CT)-DNA binding studies showed that the irradiated complexes bind to CT-DNA, whereas the nonirradiated forms bind negligibly. Studies of CT-DNA interactions in cell-free media suggest combined weak monofunctional coordinative and intercalative binding modes. The RuII arene complexes [(η6-p-cym)Ru(bpm)(Py)]2+ (1), [(η6-p-cym)Ru(bpm)(4-MeOPy)]2+ (3), [(η6-p-cym)Ru(4,4′-bpy)]2+ (4), [(η6-hmb)Ru(bpm)(Py)]2+ (8), [(η6-ind)Ru(bpm)(Py)]2+ (9), [(η6-p-cym)Ru(phen)(Py)]2+ (10), [(η6-p-cym)Ru(bathophen)(Py)]2+ (12), [(η6-p-cym)Ru(bpm)(NA)]2+ (15), and [(η6-p-cym)Ru(bpm)(MN)]2+ (16) were cytotoxic toward A2780 human ovarian cancer cell line in the absence of photoirradiation (IC50 values in the range of 9.0–60 μM)

Integrable discretizations of derivative nonlinear Schroedinger equations

We propose integrable discretizations of derivative nonlinear Schroedinger (DNLS) equations such as the Kaup-Newell equation, the Chen-Lee-Liu equation and the Gerdjikov-Ivanov equation by constructing Lax pairs. The discrete DNLS systems admit the reduction of complex conjugation between two dependent variables and possess bi-Hamiltonian structure. Through transformations of variables and reductions, we obtain novel integrable discretizations of the nonlinear Schroedinger (NLS), modified KdV (mKdV), mixed NLS, matrix NLS, matrix KdV, matrix mKdV, coupled NLS, coupled Hirota, coupled Sasa-Satsuma and Burgers equations. We also discuss integrable discretizations of the sine-Gordon equation, the massive Thirring model and their generalizations.Comment: 24 pages, LaTeX2e (IOP style), final versio

Bipyrimidine ruthenium(II) arene complexes : structure, reactivity and cytotoxicity

The synthesis and characterization of complexes [(η6-arene)Ru(N,N′)X][PF6], where arene is para-cymene (p-cym), biphenyl (bip), ethyl benzoate (etb), hexamethylbenzene (hmb), indane (ind) or 1,2,3,4-tetrahydronaphthalene (thn), N,N′ is 2,2′-bipyrimidine (bpm) and X is Cl, Br or I, are reported, including the X-ray crystal structures of [(η6-p-cym)Ru(bpm)I][PF6], [(η6-bip)Ru(bpm)Cl][PF6], [(η6-bip)Ru(bpm)I][PF6] and [(η6-etb)Ru(bpm)Cl][PF6]. Complexes in which N,N′ is 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione or 4,7-diphenyl-1,10-phenanthroline (bathophen) were studied for comparison. The RuII arene complexes undergo ligand-exchange reactions in aqueous solution at 310 K; their half-lives for hydrolysis range from 14 to 715 min. Density functional theory calculations on [(η6-p-cym)Ru(bpm)Cl][PF6], [(η6-p-cym)Ru(bpm)Br][PF6], [(η6-p-cym)Ru(bpm)I][PF6], [(η6-bip)Ru(bpm)Cl][PF6], [(η6-bip)Ru(bpm)Br][PF6] and [(η6-bip)Ru(bpm)I][PF6] suggest that aquation occurs via an associative pathway and that the reaction is thermodynamically favourable when the leaving ligand is I > Br ≈ Cl. pK a* values for the aqua adducts of the complexes range from 6.9 to 7.32. A binding preference for 9-ethylguanine (9-EtG) compared with 9-ethyladenine (9-EtA) was observed for [(η6-p-cym)Ru(bpm)Cl][PF6], [(η6-hmb)Ru(bpm)Cl]+, [(η6-ind)Ru(bpm)Cl]+, [(η6-thn)Ru(bpm)Cl]+, [(η6-p-cym)Ru(phen)Cl]+ and [(η6-p-cym)Ru(bathophen)Cl]+ in aqueous solution at 310 K. The X-ray crystal structure of the guanine complex [(η6-p-cym)Ru(bpm)(9-EtG-N7)][PF6]2 shows multiple hydrogen bonding. Density functional theory calculations show that the 9-EtG adducts of all complexes are thermodynamically preferred compared with those of 9-EtA. However, the bmp complexes are inactive towards A2780 human ovarian cancer cells. Calf thymus DNA interactions for [(η6-p-cym)Ru(bpm)Cl][PF6] and [(η6-p-cym)Ru(phen)Cl][PF6] consist of weak coordinative, intercalative and monofunctional coordination. Binding to biomolecules such as glutathione may play a role in deactivating the bpm complexes

Hamiltonians separable in cartesian coordinates and third-order integrals of motion

We present in this article all Hamiltonian systems in E(2) that are separable in cartesian coordinates and that admit a third-order integral, both in quantum and in classical mechanics. Many of these superintegrable systems are new, and it is seen that there exists a relation between quantum superintegrable potentials, invariant solutions of the Korteweg-De Vries equation and the Painlev\'e transcendents.Comment: 19 pages, Will be published in J. Math. Phy

Adaptive NLMS Partial Crosstalk Cancellation in Digital Subscriber Lines

Crosstalk is a major limitation to achieving high data-rates in next generation VDSL systems. Whilst crosstalk cancellation can be applied to completely remove crosstalk, it is often too complex for application in typical VDSL binders, which can contain up to hundreds of lines. A practical alternative, known as partial cancellation limits the cancellation to crosstalkers that cause severe interference to the other lines within the binder. In real VDSL systems, the crosstalk environment changes rapidly as new lines come online; old lines go offline, and the crosstalk channels change with fluctuations in ambient temperature. Therefore, adaptive crosstalk cancellers are often required. In this paper, we propose a new detection guided adaptive NLMS method for Adaptive Partial Crosstalk Cancellation that detects significant crosstalkers and tracks variations in their crosstalk channels. This exploits the sparse and column-wise diagonal dominant properties of the crosstalk channel matrix and leads to fast convergence, accurate crosstalk channel tracking, with a lower update complexity. The end result is an adaptive Partial Crosstalk Cancellation algorithm that has lower run-time complexity than prior state-of-the-art whilst yielding comparatively high data-rates and reliable service

Supersymmetric version of a Gaussian irrotational compressible fluid flow

The Lie point symmetries and corresponding invariant solutions are obtained for a Gaussian, irrotational, compressible fluid flow. A supersymmetric extension of this model is then formulated through the use of a superspace and superfield formalism. The Lie superalgebra of this extended model is determined and a classification of its subalgebras is performed. The method of symmetry reduction is systematically applied in order to derive special classes of invariant solutions of the supersymmetric model. Several new types of algebraic, hyperbolic, multi-solitonic and doubly periodic solutions are obtained in explicit form.Comment: Expanded introduction and added new section on classical Gaussian fluid flow. Included several additional reference