Digital simulation error curves for a spring-mass-damper system

Plotting digital simulation errors for a spring-mass-damper system and using these error curves to select type of integration, feedback update method, and number of samples per cycle at resonance reduces excessive number of samples per cycle and unnecessary iterations

Cosmic Microwave and Infrared Backgrounds cross-correlation for ISW detection

We investigate the cross-correlation between the cosmic infrared and microwave backgrounds (CIB & CMB) anisotropies through the integrated Sachs-Wolfe effect. We first describe the CIB anisotropies using a linearly biased power spectrum, then derive the theoretical angular power spectrum of the CMB-CIB cross-correlation for different instruments and frequencies. We discuss the detectability of the ISW signal by performing a signal-to-noise (SNR) analysis with our predicted spectra. The significances obtained range from 6{\sigma} to 7{\sigma} in an ideal case, depending on the frequency ; in realistic cases which account for the presence of noise including astrophysical contaminants, the results span the range 2-5{\sigma}, depending strongly on the major contribution to the noise term.Comment: 4 pages, 1 table. Contribution to the proceedings of the International Conference on Gravitation and Cosmology, Goa, India, December, 201

The Age of the Universe and the Cosmological Constant Determined from Cosmic Microwave Background Anisotropy Measurements

If Omega_tot = 1 and structure formed from adiabatic initial conditions then the age of the Universe, as constrained by measurements of the cosmic microwave background (CMB), is t_0=14.0 +/- 0.5 Gyr. The uncertainty is surprisingly small given that CMB data alone constrain neither h nor Omega_Lambda significantly. It is due to the tight (and accidental) correlation, in these models, of the age with the angle subtended by the sound horizon on the last--scattering surface and thus with the well-determined acoustic peak locations. If we assume either the HST Key Project result h = 0.72 \pm .08 or simply that h > 0.55, we find Omega_Lambda > 0.4 at 95% confidence--another argument for dark energy, independent of supernovae observations. Our analysis is greatly simplified by the Monte Carlo Markov chain approach to Bayesian inference combined with a fast method for calculating angular power spectra.Comment: 5 pages, including 2 figures and one table final published versio

CMB Power Spectrum Estimation via Hierarchical Decomposition

We have developed a fast, accurate and generally applicable method for inferring the power spectrum and its uncertainties from maps of the cosmic microwave background (CMB) in the presence of inhomogeneous and correlated noise. For maps with 10 to 100 thousand pixels, we apply an exact power spectrum estimation algorithm to submaps of the data at various resolutions, and then combine the results in an optimal manner. To analyze larger maps efficiently one must resort to sub-optimal combinations in which cross-map power spectrum error correlations are only calculated approximately. We expect such approximations to work well in general, and in particular for the megapixel maps to come from the next generation of satellite missions.Comment: 10 pages, 5 figures, to be submitted to Phys. Rev.

Inhomogeneous reionization and the polarization of the cosmic microwave background

In a universe with inhomogeneous reionization, the ionized patches create a second order signal in the cosmic microwave background polarization anisotropy. This signal originates in the coupling of the free electron fluctuation to the quadruple moment of the temperature anisotropy. We examine the contribution from a simple inhomogeneous reionization model and find that the signal from such a process is below the detectable limits of the Planck Surveyor mission. However t he signal is above the fundamental uncertainty limit from cosmic variance, so th at a future detection with a high accuracy experiment on sub-arcminute scales is possible.Comment: 10 pages, 2 eps figures, final version accepted for publication in ApJ Letter

Evaluation of selected compounds in fruit juices as sodium metabisulfite replacements or adjuncts

Sodium metabisulfite (sulfite), butylated hydroxyanisole (BHA), potassium sorbate (sorbate) and tertiary butylhydroquinone (TBHQ) were evaluated for their antimicrobial effects on Saccharomyces cerevisiae and Saccharomyces cerevisiae NRRL Y567 in apple and grape juice. Combinations of sulfite with BHA, BHA with sorbate and sulfite with sorbate were tested to determine if the compounds interacted in an additive, synergistic or antagonistic manner. A modification of the tube dilution technique outlined by Barry (1976) was used to evaluate antimicrobial efficacy. Tubes of the appropriate juice containing increasing concentrations of an antimicrobial or antimicrobial combination were inoculated with a 24 hr yeast culture grown in the juice. These tubes were then incubated 24 hr at 32°C. Tubes showing no visible growth after this time were considered to contain a concentration of antimicrobial (s) which was inhibitory to the yeast. Tubes with antimicrobial free juice were then inoculated with juice from the tubes showing no growth and incubated as before. Antimicrobial concentrations that prevented visible growth in these tubes after this additional 24 hr incubation were considered to be lethal to the yeast. The individual antimicrobials inhibited S. cerevisiae in apple juice at the following concentrations: 80 μg/ml sulfite, 160 μg/ml BHA, 500 μg/ml sorbate and 600 μg/ml TBHQ. In grape juice against this yeast, the inhibitory concentrations were 80 μg/ml sulfite, 140 μg/ml BHA, 600 μg/ml sorbate and 900 μg/ml TBHQ. When these compounds were used against S. cerevisiae NRRL Y567 in apple juice, levels of 100 μg/ml sulfite, 120 μg/ml BHA, 400 μg/ml sorbate and 600 μg/ml TBHQ effectively inhibited growth. The corresponding values for grape juice were 100 μg/ml sulfite, 160 μg/ml BHA, 400 μg/ml sorbate and 1000 μg/ml TBHQ. The lethal concentration in apple and grape juice against S. cerevisiae for sulfite was 80 μg/ml and for BHA was 160 μg/ml. Against S. cerevisiae NRRL Y567, the lethal concentration in both juices for sulfite was 120 μg/ml and for BHA was 160 μg/ml. None of the concentrations of sorbate or TBHQ were lethal to the yeast. In the combination testing, all combinations proved to be additive (P\u3e0.05) in nature in both juices and with both organisms, except for the sulfite-sorbate combination in grape juice against S. cerevisiae NRRL Y567. This interaction was considered to be antagonistic in nature since higher concentrations of sulfite were needed to cause inhibition after 24 hr than in other sulfite-sorbate combinations. It was concluded, that combining the antimicrobials would allow for a reduction in sulfite concentration but no significant gain in antimicrobial activity would occur