Spherical Redshift Distortions

Peculiar velocities induce apparent line of sight displacements of galaxies in redshift space, distorting the pattern of clustering in the radial versus transverse directions. On large scales, the amplitude of the distortion yields a measure of the dimensionless linear growth rate $\beta \approx \Omega^{0.6}/b$, where $\Omega$ is the cosmological density and $b$ the linear bias factor. To make the maximum statistical use of the data in a wide angle redshift survey, and for the greatest accuracy, the spherical character of the distortion needs to be treated properly, rather than in the simpler plane parallel approximation. In the linear regime, the redshift space correlation function is described by a spherical distortion operator acting on the true correlation function. It is pointed out here that there exists an operator, which is essentially the logarithmic derivative with respect to pair separation, which both commutes with the spherical distortion operator, and at the same time defines a characteristic scale of separation. The correlation function can be expanded in eigenfunctions of this operator, and these eigenfunctions are eigenfunctions of the distortion operator. Ratios of the observed amplitudes of the eigenfunctions yield measures of the linear growth rate $\beta$ in a manner independent of the shape of the correlation function. More generally, the logarithmic derivative $\partial/\partial\ln r$ with respect to depth $r$, along with the square $L^2$ and component $L_z$ of the angular momentum operator, form a complete set of commuting operators for the spherical distortion operator acting on the density. The eigenfunctions of this complete set of operators are spherical waves about the observer, with radial part lying in logarithmic real or Fourier space.Comment: 15 pages, with 1 embedded EPS figur

A note on dual giant gravitons in AdS4×CP3AdS_{4}\times \mathbb{CP}^{3}

We study some of the properties of dual giant gravitons - D2-branes wrapped on an $S^{2}\subset AdS_{4}$ - in type IIA string theory on $AdS_{4}\times \mathbb{CP}^{3}$. In particular we confirm that the spectrum of small fluctuations about the giant is both real and independent of the size of the graviton. We also extend previously developed techniques for attaching open strings to giants to this D2-brane giant and focus on two particular limits of the resulting string sigma model: In the pp-wave limit we quantize the string and compute the spectrum of bosonic excitations while in the semiclassical limit, we read off the fast string Polyakov action and comment on the comparison to the Landau-Lifshitz action for the dual open spin chain.Comment: v3 significantly changed: added coupling to RR 1-form and turned on worldvolume gauge field, computed gauge field fluctuation, added comments on closure of the sl(2) sector and re-written to improve clarity. This version published in JHE

THE ROLE OF CLIMATE INFORMATION IN TOURIST DESTINATION CHOICE DECISION-MAKING

This study examines if tourists actively inform themselves about the climate of their planned destination. In addition, we examine where they inform themselves and at what point in the holiday decision-making process. A self-administered questionnaire was distributed to tourists at the airport, international bus station, and the train station in Hamburg during July and August 2004. Of the 394 respondents, 73% stated that they informed themselves about the climate of their destination. Moreover, the majority of them informed themselves about climate before booking (42%). Nevertheless, a large percentage of the tourists sampled state that they informed themselves shortly before their trip. Interestingly, a significantly large share of the respondents said that they checked the weather at their destination in the week before their trip.Tourist decision-making, destination image, information search, climate, weather

Infrared diode laser spectroscopy of the fundamental band of NF(a1Δ)

Thirty-one lines of the fundamental vibration–rotation band of the NF free radical in its a 1 state have been detected in absorption near 8.6 µm using a tunable infrared diode laser. Linewidths were Doppler limited and several transitions were accompanied by resolved hyperfine structure due to fluorine and nitrogen nuclear moments. Wave number calibration using accurately determined N2O lines yielded v0 = 1165.952±0.001 cm^−1 for the band center. Rotational and centrifugal distortion constants for both v = 0 and 1 states have also been determined

Nonlinear Torsional Wave Beams

An evolution equation with cubic nonlinearity is presented for a torsional wave beam in an isotropic elastic solid. Analytical solutions are presented for the fundamental and third harmonic in the far field of a uniform circular source. Numerical results are presented for harmonic beam patterns at an intermediate distance between the near and far fields, and for a torsional waveform with shocks.Applied Research Laboratorie

Old open clusters: UBGVRI photometry of NGC 2506

UBGVRI photometry for the open cluster NGC 2506 is presented. From comparison of the observed colour-magnitude diagrams with simulations based on stellar evolutionary models we derive in a self consistent way reddening, distance, and age of the cluster: E(B-V)=0-0.07, (m-M)o = 12.6, age = 1.5-2.2 Gyr. The cluster shows a well definite secondary sequence, suggesting that binary systems constitute about 20 % of the cluster members visible in the colour-magnitude diagram.Comment: 11 pages, 7 figures, MNRAS latex style, accepte

Multiband Mechanism for the Sign Reversal of Coulomb Drag Observed in Double Bilayer Graphene Heterostructures

Coupled 2D sheets of electrons and holes are predicted to support novel quantum phases. Two experiments of Coulomb drag in electron-hole (e-h) double bilayer graphene (DBLG) have reported an unexplained and puzzling sign reversal of the drag signal. However, we show that this effect is due to the multiband character of DBLG. Our multiband Fermi liquid theory produces excellent agreement and captures the key features of the experimental drag resistance for all temperatures. This demonstrates the importance of multiband effects in DBLG: they have a strong effect not only on superfluidity, but also on the drag.Comment: 5 pages, 3 figure

Coupled Pulsation And Translation Of A Gas Bubble And Rigid Particle

A nonlinear analytic model describing the interaction of a spherical gas bubble and spherical rigid particle is presented. Both the bubble and particle are free to translate. The model is accurate to fifth order in terms of a nondimensional expansion parameter R/d, where R is a characteristic radius and d is the distance separating the bubble and particle. Numerical simulation results are presented to demonstrate the effects of key particle parameters and an external acoustic source.Applied Research Laboratorie