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

Comment on "Formation of primordial black holes by cosmic strings"

We show that in a pioneering paper by Polnarev and Zembowicz, some conclusions concerning the characteristics of the Turok-strings are generally not correct. In addition we show that the probability of string collapse given there, is off by a large prefactor (~1000).Comment: 5 pages, LaTeX and 1 figure, postscript. To appear in PR

MCMC Exploration of Supermassive Black Hole Binary Inspirals

The Laser Interferometer Space Antenna will be able to detect the inspiral and merger of Super Massive Black Hole Binaries (SMBHBs) anywhere in the Universe. Standard matched filtering techniques can be used to detect and characterize these systems. Markov Chain Monte Carlo (MCMC) methods are ideally suited to this and other LISA data analysis problems as they are able to efficiently handle models with large dimensions. Here we compare the posterior parameter distributions derived by an MCMC algorithm with the distributions predicted by the Fisher information matrix. We find excellent agreement for the extrinsic parameters, while the Fisher matrix slightly overestimates errors in the intrinsic parameters.Comment: Submitted to CQG as a GWDAW-10 Conference Proceedings, 9 pages, 5 figures, Published Versio

Evolution of magnetic states in frustrated diamond lattice antiferromagnetic Co(Al1-xCox)2O4 spinels

Using neutron powder diffraction and Monte-Carlo simulations we show that a spin-liquid regime emerges at $all compositions in the diamond-lattice antiferromagnets Co(Al1-xCox)2O4. This spin-liquid regime induced by frustration due to the second-neighbour exchange coupling J2, is gradually superseded by antiferromagnetic collinear long-range order (k=0) at low temperatures. Upon substitution of Al3+ by Co3+ in the octahedral B-site the temperature range occupied by the spin-liquid regime narrows and TN increases. To explain the experimental observations we considered magnetic anisotropy D or third-neighbour exchange coupling J3 as degeneracy-breaking perturbations. We conclude that Co(Al1-xCox)2O4 is below the theoretical critical point J2/J1=1/8, and that magnetic anisotropy assists in selecting a collinear long-range ordered ground state, which becomes more stable with increasing x due to a higher efficiency of O-Co3+-O as an interaction path compared to O-Al3+-O

A study of quantum decoherence in a system with Kolmogorov-Arnol'd-Moser tori

We present an experimental and numerical study of the effects of decoherence on a quantum system whose classical analogue has Kolmogorov-Arnol'd-Moser (KAM) tori in its phase space. Atoms are prepared in a caesium magneto-optical trap at temperatures and densities which necessitate a quantum description. This real quantum system is coupled to the environment via spontaneous emission. The degree of coupling is varied and the effects of this coupling on the quantum coherence of the system are studied. When the classical diffusion through a partially broken torus is < hbar, diffusion of quantum particles is inhibited. We find that increasing decoherence via spontaneous emission increases the transport of quantum particles through the boundary.Comment: 19 pages including 6 figure

Cosmic String Loops Collapsing to Black Holes

We reexamine the question of collapse of Turok's two-parameter family of cosmic strings. We first give a few simple explicit examples showing that previously obtained results in the literature cannot generally be correct in the complete two-dimensional parameter-space. We then perform a classification of the strings according to the specific time(s) the minimal string size is reached during one period. Finally we obtain an exact analytical expression for the probability of collapse to black holes for the Turok strings. Our result has the same general behavior as previously obtained in the literature but we find, in addition, a numerical prefactor that changes the result by approximately a factor 2000

Southwestern Minnesota Farm Business Management Association 2008 Annual Report

Average net farm income was $190,901 in 2008 for the 99 farms included in this annual report of the Southwestern Minnesota Farm Business Management Association. Average earnings decreased by 21$242,267 in 2007 (Figure 1). 2008 ended a steady trend of increasing year-to-year incomes for these farms from 2001 to 2007. Crop farms, with historically high corn and soybean prices, remained very profitable. However, specialized hog farms, which had been very profitable for the past four years, experienced substantial losses. Highlights of association financial results for 2008: Median net farm income was $178,874, slightly lower than the average, indicating that the average was increased by high profits of the most profitable farms. This effect was not as large as previous years, likely because of losses by larger hog operations. • The difference between the most profitable farms and the least profitable continued to increase. The most profitable 20$449,997 while the least profitable lost $-29,476. • Average gross cash income increased by 20$115,999. The average debt-to-asset ratio improved slightly to 39%, down from 40% (Figure 4). • Corn yields were up but soybean yields were down. Corn averaged 172 bushels per acre compared to 162 in 2007. Soybeans yields decreased to 44 bushels from 49 in 2007 (Figure 5). • Both corn and soybean prices received increased by over 50% to $4.51 for corn and$10.83 for soybeans. • The cost to raise an acre of corn (with land rent) increased by 23% while soybean costs increased by 21%. The cost to produce a bushel of corn on cash rented land increased from $2.58 per bushel in 2007 to$2.90 in 2008, while soybean costs per bushel increased from $6.14 to$7.21. • The average specialized hog operation (those with 70% of sales from hogs or pigs) lost over $150,000 in 2008 (Figure 6). All other farm types with enough farms to report averaged net incomes very close to the association average. • Based on rate of return on assets, crop farms (those with 70$1,000,000, were the least profitable based on rate of return on assets. This group earned an average ROA of 7% compared to 14% for farms that grossed between $500,000 and$1,000,000. • With exceptionally high feed prices, no hog or beef enterprise, with the exception of contract growing of hogs (where the contractor provided the feed) covered even direct costs of production. The report provides additional information on profitability, liquidity, and solvency as well as other whole-farm information and detailed information on crop and livestock enterprises. Also reported are whole-farm financial condition and performance by county, sales size class, type of farm, debt-to-asset ratio, and age of operator.Agricultural Finance, Farm Management,

Surfaces Meeting Porous Sets in Positive Measure

Let n>2 and X be a Banach space of dimension strictly greater than n. We show there exists a directionally porous set P in X for which the set of C^1 surfaces of dimension n meeting P in positive measure is not meager. If X is separable this leads to a decomposition of X into a countable union of directionally porous sets and a set which is null on residually many C^1 surfaces of dimension n. This is of interest in the study of certain classes of null sets used to investigate differentiability of Lipschitz functions on Banach spaces