Origin of the Mott Gap

We show exactly that the only charged excitations that exist in the strong-coupling limit of the half-filled Hubbard model are gapped composite excitations generated by the dynamics of the charge $2e$ boson that appears upon explicit integration of the high-energy scale. At every momentum, such excitations have non-zero spectral weight at two distinct energy scales separated by the on-site repulsion $U$. The result is a gap in the spectrum for the composite excitations accompanied by a discontinuous vanishing of the density of states at the chemical potential when $U$ exceeds the bandwidth. Consequently, we resolve the long-standing problem of the cause of the charge gap in a half-filled band in the absence of symmetry breaking.Comment: 6 pages, 2 figures: Expanded Published versio

Search for Rapid Changes in the Visible-Light Corona during the 21 June 2001 Total Solar Eclipse

Some 8000 images obtained with the SECIS fast-frame CCD camera instrument located at Lusaka, Zambia, during the total eclipse of 21 June 2001 have been analyzed to search for short-period oscillations in intensity that could be a signature of solar coronal heating mechanisms by MHD wave dissipation. Images were taken in white- light and Fe XIV green-line (5303 A) channels over 205 seconds (frame rate 39 s-1), approximately the length of eclipse totality at this location, with a pixel size of four arcseconds square. The data are of considerably better quality than were obtained during the 11 August 1999 total eclipse, observed by us (Rudawy et al.: Astron. Astrophys. 416, 1179, 2004), in that the images are much better exposed and enhancements in the drive system of the heliostat used gave a much improved image stability. Classical Fourier and wavelet techniques have been used to analyze the emission at 29518 locations, of which 10714 had emission at reasonably high levels, searching for periodic fluctuations with periods in the range 0.1-17 seconds (frequencies 0.06-10 Hz). While a number of possible periodicities were apparent in the wavelet analysis, none of the spatially and time-limited periodicities in the local brightness curves was found to be physically important. This implies that the pervasive Alfven wave-like phenomena (Tomczyk et al.: Science 317, 1192, 2007) using polarimetric observations with the CoMP instrument do not give rise to significant oscillatory intensity fluctuations.Comment: Accepted by Solar Physics; 16 figure

Rainfall and runoff data for Hinkson and Grindstone creeks at Columbia, MO.

"A thesis for the degree of bachelor of science in civil engineering. University of Missouri, Department of Engineering, 1909.""The investigation presented in these notes has resulted more satisfactorily than was anticipated when the work was first undertaken. We feel perfectly satisfied with the results herewith submitted as far as they go, but regret that the period of investigation was not of sufficient duration to give more nearly average results, particularly in regard to the conditions during the summer months. In the preparation of this paper, we are especially indebted to Professor T. J. Rodhouse, in charge of the Hydraulic Engineering, University of Missouri, under whose supervision the work was carried out and whose counsel has guided us throughout the work. Our appreciation and thanks are justly due Mr. George Reeder, Director Missouri section, U.S.weather Bureau, who furnished the rainfall data, with other valuable information; to the members of the Engineering faculty in general, for their suggestions and assistance; and to the members of the senior Engineering class who have assisted in some of the field work."--Forewor

New Soybean Varieties

Several new soybean varieties have been released during the past few months. Many have appeared in the Uniform Soybean Nurseries at Henderson or Fulton as number strains or named varieties. The following abbreviated descriptions may be of help in comparing these newer releases with more widely known material

Notice of Release of Custer Soybean

The Crops Research Division, Agricultural Research Service, and the cooperators listed above announce the release of a new phytophthora and cyst nematode-resistant soybean variety named Custer. Custer is the second cyst nematode-resistant variety to be released. It is earlier than the previously released variety Pickett

Field Trials with Zinc on Corn

Zinc deficiency in corn has been found in isolated instances in Kentucky during the past few years. Usually the deficiency is found in fields having a high pH or in high-phosphate soils with somewhat lower pH values. At present zinc deficiency in Kentucky soils does not appear widespread enough to justify recommending its application except where known deficiencies exist

Development of Replacement Heifers using Combinations of Three Forage Types and Feed Supplements (with or without Broiler Litter)

The proper management of replacement heifers is an essential component of successful cow/calf operations. The level of management and nutrition applied to replacement heifers as calves and yearlings can impact their subsequent reproductive performance and productivity