Gravitational power from cosmic string loops with many kinks

We investigate the effect of a large number of kinks on the gravitational power radiated by cosmic string loops. We show that the total power radiated by a loop with N left-moving and right-moving kinks is proportional to N and increases with the typical kink angle. We then apply these results to loops containing junctions which give rise to a proliferation of the number of sharp kinks. We show that the time of gravitational decay of these loops is smaller than previously assumed. In light of this we revisit the gravitational wave burst predictions from a network containing such loops. We find there is no parameter regime in which the rate of individual kink bursts is enhanced with respect to standard networks. By contrast, there remains a region of parameter space for which the kink-kink bursts dominate the stochastic background. Finally, we discuss the order of magnitude of the typical number of sharp kinks resulting from kink proliferation on loops with junctions.Comment: 20 pages, 1 figur

Gravitational Wave Bursts from Cosmic Superstrings with Y-junctions

Cosmic superstring loops generically contain strings of different tensions that meet at Y-junctions. These loops evolve non-periodically in time, and have cusps and kinks that interact with the junctions. We study the effect of junctions on the gravitational wave signal emanating from cosmic string cusps and kinks. We find that earlier results on the strength of individual bursts from cusps and kinks on strings without junctions remain largely unchanged, but junctions give rise to additional contributions to the gravitational wave signal coming from strings expanding at the speed of light at a junction and kinks passing through a junction.Comment: 20 pages, 5 figure

The electrochemical behaviour of polycrystalline nickel electrodes in different carbonate-bicarbonate ion-containing solutions

The dissolution and passivation of polycrystalline nickel in carbonate-bicarbonate ion-containing solutions covering wide ranges of pH and electrolyte concentration were investigated by employing voltammetric, galvanostatic and potentiostatic transient techniques. Results obtained with a rotating disc electrode allow the competing reactions related to the active-passive transition to be distinguished through the influence of the potential sweep rate and the rotation speed on the electrochemical behaviour of the system at fixed concentrations of either carbonate or bicarbonate ion. The first oxidation level of nickel corresponds mainly to Ni(OH)2 formation, the chemical dissolution of the surface layer and the precipitation of NiCO3 and Ni(OH)2. The partial removal of the prepassive layer is predominantly assisted by both the bicarbonate ion concentration and the electrode rotation. In the presence of chloride ions the formation of soluble Ni(II) species and NiCo3 in the potential range of the first oxidation level appears to be enhanced. This effect can be interpreted by taking into account competitive adsorption processes at the base metal between Cl− and OH− ions.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

New biphenyl iminium salt catalysts for highly enantioselective asymmetric epoxidation: role of additional substitution and dihedral angle

New biaryl iminium salt catalysts for enantioselective alkene epoxidation containing additional substitution in the heterocyclic ring are reported. The effects upon conformation and enantioselectivity of this additional substitution, and the influence of dihedral angle in these systems, has been investigated using a synthetic approach supported by density functional theory. Enantioselectivities of up to 97% ee were observed

eLISA: Astrophysics and cosmology in the millihertz regime

This document introduces the exciting and fundamentally new science and astronomy that the European New Gravitational Wave Observatory (NGO) mission (derived from the previous LISA proposal) will deliver. The mission (which we will refer to by its informal name "eLISA") will survey for the first time the low-frequency gravitational wave band (about 0.1 mHz to 1 Hz), with sufficient sensitivity to detect interesting individual astrophysical sources out to z = 15. The eLISA mission will discover and study a variety of cosmic events and systems with high sensitivity: coalescences of massive black holes binaries, brought together by galaxy mergers; mergers of earlier, less-massive black holes during the epoch of hierarchical galaxy and black-hole growth; stellar-mass black holes and compact stars in orbits just skimming the horizons of massive black holes in galactic nuclei of the present era; extremely compact white dwarf binaries in our Galaxy, a rich source of information about binary evolution and about future Type Ia supernovae; and possibly most interesting of all, the uncertain and unpredicted sources, for example relics of inflation and of the symmetry-breaking epoch directly after the Big Bang. eLISA's measurements will allow detailed studies of these signals with high signal-to-noise ratio, addressing most of the key scientific questions raised by ESA's Cosmic Vision programme in the areas of astrophysics and cosmology. They will also provide stringent tests of general relativity in the strong-field dynamical regime, which cannot be probed in any other way. This document not only describes the science but also gives an overview on the mission design and orbits

Potential antiproteolytic effects of L-leucine: observations of in vitro and in vivo studies

The purpose of present review is to describe the effect of leucine supplementation on skeletal muscle proteolysis suppression in both in vivo and in vitro studies. Most studies, using in vitro methodology, incubated skeletal muscles with leucine with different doses and the results suggests that there is a dose-dependent effect. The same responses can be observed in in vivo studies. Importantly, the leucine effects on skeletal muscle protein synthesis are not always connected to the inhibition of skeletal muscle proteolysis. As a matter of fact, high doses of leucine incubation can promote suppression of muscle proteolysis without additional effects on protein synthesis, and low leucine doses improve skeletal muscle protein ynthesis but have no effect on skeletal muscle proteolysis. These research findings may have an important clinical relevancy, because muscle loss in atrophic states would be reversed by specific leucine supplementation doses. Additionally, it has been clearly demonstrated that leucine administration suppresses skeletal muscle proteolysis in various catabolic states. Thus, if protein metabolism changes during different atrophic conditions, it is not surprising that the leucine dose-effect relationship must also change, according to atrophy or pathological state and catabolism magnitude. In conclusion, leucine has a potential role on attenuate skeletal muscle proteolysis. Future studies will help to sharpen the leucine efficacy on skeletal muscle protein degradation during several atrophic states

Orbital effects of a monochromatic plane gravitational wave with ultra-low frequency incident on a gravitationally bound two-body system

We analytically compute the long-term orbital variations of a test particle orbiting a central body acted upon by an incident monochromatic plane gravitational wave. We assume that the characteristic size of the perturbed two-body system is much smaller than the wavelength of the wave. Moreover, we also suppose that the wave's frequency is much smaller than the particle's orbital one. We make neither a priori assumptions about the direction of the wavevector nor on the orbital geometry of the planet. We find that, while the semi-major axis is left unaffected, the eccentricity, the inclination, the longitude of the ascending node, the longitude of pericenter and the mean anomaly undergo non-vanishing long-term changes. They are not secular trends because of the slow modulation introduced by the tidal matrix coefficients and by the orbital elements themselves. They could be useful to indepenedently constrain the ultra-low frequency waves which may have been indirectly detected in the BICEP2 experiment. Our calculation holds, in general, for any gravitationally bound two-body system whose characteristic frequency is much larger than the frequency of the external wave. It is also valid for a generic perturbation of tidal type with constant coefficients over timescales of the order of the orbital period of the perturbed particle.Comment: LaTex2e, 24 pages, no figures, no tables. Changes suggested by the referees include