c-Axis longitudinal magnetoresistance of the electron-doped superconductor Pr1.85Ce0.15CuO4

We report c-axis resistivity and longitudinal magnetoresistance measurements of superconducting Pr1.85Ce0.15CuO4 single crystals. In the temperature range 13K<T<32K, a negative magnetoresistance is observed at fields just above Hc2. Our studies suggest that this negative magnetoresistance is caused by superconducting fluctuations. At lower temperatures (T<13K), a different magnetoresistance behavior and a resistivity upturn are observed, whose origin is still unknown.Comment: Accepted for publication in Phys. Rev.

Comparing key compositional indicators in Jupiter with those in extra-solar giant planets

Spectroscopic transiting observations of the atmospheres of hot Jupiters around other stars, first with Hubble Space Telescope and then Spitzer, opened the door to compositional studies of exoplanets. The James Webb Space Telescope will provide such a profound improvement in signal-to-noise ratio that it will enable detailed analysis of molecular abundances, including but not limited to determining abundances of all the major carbon- and oxygen-bearing species in hot Jupiter atmospheres. This will allow determination of the carbon-to-oxygen ratio, an essential number for planet formation models and a motivating goal of the Juno mission currently around JupiterComment: Submitted to the Astro2020 Decadal Survey as a white paper; thematic areas "Planetary Systems" and "Star and Planet Formation

High Harmonic Generation in SF6_{6}: Raman-excited Vibrational Quantum Beats

In a recent experiment (N. Wagner et al., PNAS v103, p13279) on SF$_{6}$, a high-harmonic generating laser pulse is preceded by a pump pulse which stimulates Raman-active modes in the molecule. Varying the time delay between the two pulses modulates high harmonic intensity, with frequencies equal to the vibration frequencies of the Raman-active modes. We propose an explanation of this modulation as a quantum interference between competing pathways that occur via adjacent vibrational states of the molecule. The Raman and high harmonic processes act as beamsplitters, producing vibrational quantum beats among the Raman-active vibrational modes that are excited by the first pulse. We introduce a rigorous treatment of the electron-ion recombination process and the effect of the ionic Coulomb field in the electron propagation outside the molecule, improving over the widely-used three-step model.Comment: submitted to PR

The Theatre and Sustainable Human Development: Fumes of Fuel and Boundless Love as Paradigms

The performing Arts encompass a wide range of disciplines which are invariably synonymous with creativity, thus, creativity is the hallmark of performance. For the sake of clarity, Performing Arts comprise Theatre Arts, Music, Dance and Choreography and the electronic media of Radio, Television and film commonly referred to as the audio-visual or media arts. Development is invariably measured by performance using certain indices. It is also part of the function of the performing arts to project development as well be evidence of development themselves. For instance, it is a sign of development to produce a play before an audience, particularly an audience composed of persons saddled with the responsibility of showing the direction for the development of a certain society. This paper will use the plays, Fumes of Fuel and Boundless Love to expound on the relevance of the Performing Arts in human and societal development.Keywords: Performing Arts, Creativity, Development and Humanity

The Standard Model on a D-brane

We present a consistent string theory model which reproduces the Standard Model, consisting of a D3-brane at a simple orbifold singularity. We study some simple features of the phenomenology of the model. We find that the scale of stringy physics must be in the multi-TeV range. There are natural hierarchies in the fermion spectrum and there are several possible experimental signatures of the model.Comment: 8 pages Latex, 1 fig. v2: discussion improved, added new reference

Interpolation in non-positively curved K\"ahler manifolds

We extend to any simply connected K\"ahler manifold with non-positive sectional curvature some conditions for interpolation in $\mathbb{C}$ and in the unit disk given by Berndtsson, Ortega-Cerd\`a and Seip. The main tool is a comparison theorem for the Hessian in K\"ahler geometry due to Greene, Wu and Siu, Yau.Comment: 9 pages, Late

On the Possible Common Nature of Double Extensive Air Showers and Aligned Events

Double Extensive Air Showers and aligned events were discovered at energies E {\gtsim} 1016 eV over fourth century back. But up to now there is no sufficiently identical explanation of their nature. In this paper it is expected that both types of events are the result of breakup of the string formed in the collisions of super high energy particles

Universal diffusion near the golden chaos border

We study local diffusion rate $D$ in Chirikov standard map near the critical golden curve. Numerical simulations confirm the predicted exponent $\alpha=5$ for the power law decay of $D$ as approaching the golden curve via principal resonances with period $q_n$ ($D \sim 1/q^{\alpha}_n$). The universal self-similar structure of diffusion between principal resonances is demonstrated and it is shown that resonances of other type play also an important role.Comment: 4 pages Latex, revtex, 3 uuencoded postscript figure

The Radio Quiescence of Active Galaxies with High Accretion Rates

We present 6 cm Very Large Array observations of the Greene & Ho (2004) sample of 19 low-mass active galaxies with high accretion rates. This is one of the only studies of a uniform sample of narrow-line Seyfert 1 (NLS1) galaxies with such high sensitivity and resolution. Although we detect only one source, the entire sample is very radio-quiet down to strong limits. GH10 was found to have a radio power of 8.5 x 10^21 W/Hz, and a ratio R = f(6 cm)/f(4400 A) of 2.8. The 3 sigma upper limits for the remaining nondetections correspond to radio powers from 3 x 10^20 to 8 x 10^21 W/Hz and 0.47 < R <9.9. Stacking all nondetections yields an even stronger upper limit of R < 0.27. An assessment of existing observations in the literature confirms our finding that NLS1s are consistently radio-quiet, with a radio-loud fraction of 0%-6%, which is significantly lower than the 10%-20% observed in the general quasar population. By analogy with stellar-mass black holes, we argue that AGNs undergo a state transition at L_bol/L_Edd~0.01. Below this value a radiatively inefficient accretion flow effectively drives an outflow, which disappears when the flow turns into an optically thick, geometrically thin disk, or a radiation pressure-dominated slim disk at still higher L_bol/L_Edd.Comment: To appear in ApJ; 8 pages, 3 figures; uses emulateapj5.st