Evidence of resonant mode coupling and the relationship between low and high frequencies in a rapidly rotating A star

In the theory of resonant mode coupling, the parent and child modes are directly related in frequency and phase. The oscillations present in the fast rotating Delta Scuti star KIC 8054146 allow us to test the most general and generic aspects of such a theory. The only direct way to separate the parent and coupled (child) modes is to examine the correlations in amplitude variability between the different frequencies. For the dominant family of related frequencies, only a single mode and a triplet are the origins of nine dominant frequency peaks ranging from 2.93 to 66.30 cycles per day (as well as dozens of small-amplitude combination modes and a predicted and detected third high-frequency triplet). The mode-coupling model correctly predicts the large amplitude variations of the coupled modes as a product of the amplitudes of the parent modes, while the phase changes are also correctly modeled. This differs from the behavior of 'normal' combination frequencies in that the amplitudes are three orders of magnitude larger and may exceed even the amplitudes of the parent modes. We show that two dominant low frequencies at 5.86 and 2.93 cycles per day in the gravity-mode region are not harmonics of each other, and their properties follow those of the almost equidistant high-frequency triplet. We note that the previously puzzling situation of finding two strong peaks in the low-frequency region related by nearly a factor of two in frequency has been seen in other Delta Scuti stars as well.Comment: To be published in the Astrophysical Journa

The ISCIP Analyst, Volume VII, Issue 11

This repository item contains a single issue of The ISCIP Analyst, an analytical review journal published from 1996 to 2010 by the Boston University Institute for the Study of Conflict, Ideology, and Policy

Fine Grid Asteroseismology Of G117-B15A And R548

We now have a good measurement of the cooling rate of G117-B15A. In the near future, we will have equally well determined cooling rates for other pulsating white dwarfs, including R548. The ability to measure their cooling rates offers us a unique way to study weakly interacting particles that would contribute to their cooling. Working toward that goal, we perform a careful asteroseismological analysis of G117-B15A and R548. We study them side by side because they have similar observed properties. We carry out a systematic, fine grid search for best-fit models to the observed period spectra of those stars. We freely vary four parameters: the effective temperature, the stellar mass, the helium layer mass, and the hydrogen layer mass. We identify and quantify a number of uncertainties associated with our models. Based on the results of that analysis and fits to the periods observed in R548 and G117-B15A, we clearly define the regions of the four-dimensional parameter space occupied by the best-fit models.NSF AST 05-07639Astronom

Fusillade Of Words: Secessionists Spoke Of Nature, Slavery, And Chivalry

In the months leading up to the War and indeed through the duration of the conflict, one heard speeches everywhere in the South, according to Voices in the Storm, a short volume by historian Karen E. Fritz. Speechmaking at first created, then sus-tained, and in the end reflected, the mood of ...

A Multiscale Study of Tropical Cyclone Formation, Structure Change, and Predictability in the Western North Pacific Region and TCS08 Experiment Support

LONG-TERM GOALS AND OBJECTIVES: The overarching objectives of this research project are to obtain an improved understanding of the formation, predictability and structure change of tropical cyclones in the Western Pacific region. During the second year of this project multiple cases have been analyzed in support of the Tropical Cyclone Structure 2008 (TCS08) field campaign. Because of space constraints, only a brief summary of these extensive results is presented here.Award Number: N001408WR2012

Repair and Replacement of Acid-Damaged Piles

A case history of the investigation and repair of severe foundation damage by sulfuric acid attack to the concrete piles supporting a chemical plant is described. In December 1975, several columns were observed to have settled up to 5 inches (13 cm). Since large quantities of sulfuric acid arc used at the plant, deterioration of concrete piles supporting the structure was suspected. An initial investigation consisting of the coring of numerous floor piles was performed in order to determine the magnitude of the problem. Because many piles were found to be severely deteriorated, underpinning of columns in the area of known damage was begun. During initial underpinning operations, additional investigations (additional coring, laboratory testing, examining piles uncovered by excavation) were performed. Ultimately, many columns were underpinned at great expense, and significant steps were taken to minimize the possibility of recurrence of the situation. The damage to concrete foundations which can occur in a hostile environment is shown dramatically. The extreme importance to the safety of the structure in minimizing acid spills and leaks into the groundwater or soil is demonstrated