The inverse problem for pulsating neutron stars: A ``fingerprint analysis'' for the supranuclear equation of state

We study the problem of detecting, and infering astrophysical information from, gravitational waves from a pulsating neutron star. We show that the fluid f and p-modes, as well as the gravitational-wave w-modes may be detectable from sources in our own galaxy, and investigate how accurately the frequencies and damping rates of these modes can be infered from a noisy gravitational-wave data stream. Based on the conclusions of this discussion we propose a strategy for revealing the supranuclear equation of state using the neutron star fingerprints: the observed frequencies of an f and a p-mode. We also discuss how well the source can be located in the sky using observations with several detectors.Comment: 9 pages, 3 figure

Quiescent cosmological singularities

The most detailed existing proposal for the structure of spacetime singularities originates in the work of Belinskii, Khalatnikov and Lifshitz. We show rigorously the correctness of this proposal in the case of analytic solutions of the Einstein equations coupled to a scalar field or stiff fluid. More specifically, we prove the existence of a family of spacetimes depending on the same number of free functions as the general solution which have the asymptotics suggested by the Belinskii-Khalatnikov-Lifshitz proposal near their singularities. In these spacetimes a neighbourhood of the singularity can be covered by a Gaussian coordinate system in which the singularity is simultaneous and the evolution at different spatial points decouples.Comment: 38 page

X-Ray Properties of the First Sunyaev-Zel'dovich Effect Selected Galaxy Cluster Sample from the South Pole Telescope

We present results of X-ray observations of a sample of 15 clusters selected via their imprint on the cosmic microwave background from the thermal Sunyaev-Zel'dovich (SZ) effect. These clusters are a subset of the first SZ-selected cluster catalog, obtained from observations of 178 deg^2 of sky surveyed by the South Pole Telescope (SPT). Using X-ray observations with Chandra and XMM-Newton, we estimate the temperature, T_X, and mass, M_g, of the intracluster medium within r_500 for each cluster. From these, we calculate Y_X = M_(g)T_X and estimate the total cluster mass using an M_(500)-Y_X scaling relation measured from previous X-ray studies. The integrated Comptonization, Y SZ, is derived from the SZ measurements, using additional information from the X-ray-measured gas density profiles and a universal temperature profile. We calculate scaling relations between the X-ray and SZ observables and find results generally consistent with other measurements and the expectations from simple self-similar behavior. Specifically, we fit a Y_(SZ)-Y_X relation and find a normalization of 0.82 ± 0.07, marginally consistent with the predicted ratio of Y_(SZ)/Y_X = 0.91 ± 0.01 that would be expected from the density and temperature models used in this work. Using the Y_X-derived mass estimates, we fit a Y_(SZ)-M_500 relation and find a slope consistent with the self-similar expectation of Y_(SZ) ∝ M^(5/3) with a normalization consistent with predictions from other X-ray studies. We find that the SZ mass estimates, derived from cosmological simulations of the SPT survey, are lower by a factor of 0.78 ± 0.06 relative to the X-ray mass estimates. This offset is at a level of 1.3σ when considering the ~15% systematic uncertainty for the simulation-based SZ masses. Overall, the X-ray measurements confirm that the scaling relations of the SZ-selected clusters are consistent with the properties of other X-ray-selected samples of massive clusters, even allowing for the broad redshift range (0.29 < z < 1.08) of the sample

BRUCE: a program for the detection of transfer-messenger RNA genes in nucleotide sequences

A computer program, BRUCE, was developed for the identification of transfer‐messenger RNA (tmRNA) genes. The program employs heuristic algorithms to search for a tRNAAla‐like secondary structure surrounding a short sequence encoding the tag peptide. In the 57 completely sequenced bacterial genomes where tmRNA genes have been reported previously, BRUCE identified all with no false positives. In addition, BRUCE found 99 of the 100 tmRNAs identified previously in other bacteria, red chloroplasts and cyanelles. The output of the program reports the proposed tRNA secondary structure, the tmRNA gene sequence and the tag peptide

The dynamics of dissipative multi-fluid neutron star cores

We present a Newtonian multi-fluid formalism for superfluid neutron star cores, focussing on the additional dissipative terms that arise when one takes into account the individual dynamical degrees of freedom associated with the coupled "fluids". The problem is of direct astrophysical interest as the nature of the dissipative terms can have significant impact on the damping of the various oscillation modes of the star and the associated gravitational-wave signatures. A particularly interesting application concerns the gravitational-wave driven instability of f- and r-modes. We apply the developed formalism to two specific three-fluid systems: (i) a hyperon core in which both Lambda and Sigma^- hyperons are present, and (ii) a core of deconfined quarks in the colour-flavour-locked phase in which a population of neutral K^0 kaons is present. The formalism is, however, general and can be applied to other problems in neutron-star dynamics (such as the effect of thermal excitations close to the superfluid transition temperature) as well as laboratory multi-fluid systems.Comment: RevTex, no figure

A COMPARISON OF MINNESOTA'S FARM BUSINESS MANAGEMENT ASSOCIATION MEMBERS AND THE USDA'S FARM COSTS AND RETURNS SURVEY

Many states have farm record associations which collect individual farm data. This data are used for research, extension, and teaching purposes. However, since membership in the associations is voluntary, the question arises whether the members are representative of the population of all farmers in that area. This study compares farm record data collected through the Southeastern and Southwestern Minnesota Farm Business Management Associations (FBMA) and data obtained through the USDA's Farm Costs and Returns Survey (FCRS). Both data sets were for 1987. By design, the FCRS survey is not subject to the self-selection bias that may occur in the FBMA data. The objectives of this study are to: (1) determine which farm characteristics are statistically the same in the FBMA and FCRS data, and (2) determine the farm size ranges in which FBMA farms are statistically representative of FCRS farms'. FBMA farms were not representative of all farms in their area. FBMA farms do not include small operations. Major differences exist in total tillable acreage, rented land and livestock production, especially hogs. These combined differences result in a substantial difference in net farm income between the two farm categories. However, the FBMA farms reflect FCRS farms' solvency conditions relatively well. FBMA farms were more similar to farms with sales exceeding $60,000 per year but differences still existed. Total acreage, total sales (especially sales of hogs), total expenses, and net farm income were significantly (p<.01) higher for FBMA farms. Even at higher sales levels, FBMA farms were characterized by a higher level of livestock production and a slightly larger tillable acreage mainly due to renting additional land. Economic performance measured by net farm income and returns to total assets and family labor also was significantly (p<.01) better for FBMA farms. So even though differences in assets, liabilities, and thus solvency positions were insignificant (p>.10), the economic performance of the FBMA farms appears to be better than FCRS farms even in larger sizes. On the basis of these findings, the FBMA data cannot be used to represent all farms or even all commercial farms. It does appear that FBMA farms can be used to represent larger farms with livestock. Thus, the FBMA data is not well-suited for estimation of economic relationships to be used in aggregate economic analyses of the agricultural sector.Farm Management,

ON THE OSCILLATION SPECTRA OF ULTRA COMPACT STARS

Quasinormal modes of ultra compact stars with uniform energy density have been calculated. For less compact stars, there is only one very slowly damped polar mode (corresponding to the Kelvin f-mode) for each spherical harmonic index $l$. Further long-lived modes become possible for a sufficiently compact star (roughly when $M/R \ge 1/3$). We compare the characteristic frequencies of these resonant polar modes to the axial modes first found by Chandrasekhar and Ferrari [{\em Proc. Roy. Soc. London A} {\bf 434} 449 (1991)]. We find that the two spectra approach each other as the star is made more compact. The oscillation frequencies of the corresponding polar and axial modes agree to within a percent for stars more compact than $M/R = 0.42$. At the same time, the damping times are slightly different. The results illustrate that there is no real difference between the origin of these axial and polar modes: They are essentially spacetime modes.Comment: 13 pages, LATEX format, 25Kb, 2 postscript figures, Proc. Roy. Soc. London in pres