Ferromagnetism in Fe-doped Ba6Ge25 Chiral Clathrate

We have successfully synthesized a Ba6Ge25 clathrate, substituting 3 Fe per formula unit by Ge. This chiral clathrate has Ge sites forming a framework of closed cages and helical tunnel networks. Fe atoms randomly occupy these sites, and exhibit high-spin magnetic moments. A ferromagnetic transition is observed with Tc = 170 K, the highest observed Tc for a magnetic clathrate. However, the magnetic phase is significantly disordered, and exhibits a transformation to a re-entrant spin glass phase. This system has a number of features in common with other dilute magnetic semiconductors.Comment: Submitted to Applied Physics Letters. Fig. 1 resolution reduced for online archive versio

Quark-Meson Coupling model based upon the Nambu-Jona Lasinio model

The NJL model for the octet baryons, using proper time regularization to simulate some of the features of confinement, is solved self-consistently in nuclear matter. This provides an alternative framework to the MIT bag model which has been used in the quark-meson coupling model. After fitting the parameters of the model to the saturation properties of symmetric nuclear matter the model is used to explore the equation of state of pure neutron matter as well as nuclear matter at densities relevant to heavy ion collisions. With a view to future studies of high mass neutron stars, the binding of hyperons is also explored.Comment: 7 pages and 4 figure

A Panel of Price Indices for Housing, Other Goods, and All Goods for All Areas in the United States 1982-2008

This paper produces a panel of price indices for housing, other produced goods, and all produced goods for each metropolitan area in the United States and the non-metropolitan part of each state from 1982 through 2008 that can be used for estimating behavioral relationships, studying the workings of markets, and assessing differences in the economic circumstances of people living in different areas. Our general approach is to first produce cross-sectional price indices for a single year 2000 and then use BLS time-series price indices to create the panel. Our geographic housing price index for 2000 is based on a large data set with detailed information about the characteristics of dwelling units and their neighborhoods throughout the United States that enables us to overcome many shortcomings of existing interarea housing price indices. For most areas, our price index for all goods other than housing is calculated from the price indices for categories of non-housing goods produced each quarter by the Council for Community and Economic Research. In order to produce a non-housing price index for areas of the United States not covered by their index, we estimate a theoretically-based regression model explaining differences in the composite price index for non-housing goods for areas where it is available and use it to predict a price of other goods for the uncovered areas. The overall consumer price index for all areas is based on the preceding estimates of the price of housing and other goods. The paper also discusses existing interarea price indices available to researchers, and it compares the new housing price index with housing price indices based on alternative methods using the same data and price indices based on alternative data sets. Electronic versions of the price indices are available online.Interarea price indices, interarea housing price indices, geographic cost-of-living differences, geographic price differences

Observations on the Overwintering Potential of the Striped Cucumber Beetle (Coleoptera: Chrysomelidae) in Southern Minnesota

The striped cucumber beetle, Acalymma vittatum (Fabricius) (Coleoptera: Chrysomelidae), is an important pest of cucurbit crops. However, the overwinter- ing capacity of this pest in temperate regions is poorly understood. In this study, the in-field survival of A. vittatum was examined during three consecutive winters. In addition, the supercooling points of A. vittatum were determined as an index of cold hardiness for adults. During each winter, the survival of adults decreased significantly through time, with no individuals surviving until spring. By comparing the supercooling points and in-field survival of adults to soil temperatures, it appears that winter temperatures in Minnesota are cold enough to induce freezing of the beetles. Moreover, a considerable amount of mortality occurred before minimum monthly soil temperatures dropped below the supercooling point of overwintering individuals, suggesting the occurrence of prefreeze mortality. An improved understanding of the response of A. vittatum to winter temperatures in temperate regions may aid in early season management of this pest

Rho meson form factors in a confining Nambu--Jona-Lasinio model

Elastic electromagnetic form factors for the $\rho^+$ meson are calculated in a Nambu--Jona-Lasinio model which incorporates quark confinement through the use of the proper-time regularization scheme. A comparison is made with recent lattice QCD results and previous quark model calculations for static quantities and the Sachs form factors. The results are qualitatively in good agreement with the lattice QCD calculations, with the exception of the quadrupole moment and corresponding form factor, which may be related to a lack of spherical symmetry on the lattice.Comment: 8 pages, 11 figure

Baryon Octet Electromagnetic Form Factors in a confining NJL model

Electromagnetic form factors of the baryon octet are studied using a Nambu--Jona-Lasinio model which utilizes the proper-time regularization scheme to simulate aspects of colour confinement. In addition, the model also incorporates corrections to the dressed quarks from vector meson correlations in the t-channel and the pion cloud. Comparison with recent chiral extrapolations of lattice QCD results shows a remarkable level of consistency. For the charge radii we find the surprising result $r_{E}^p < r_{E}^{\Sigma^+}$ and $|r_{E}^n| < |r_{E}^{\Xi^0}|$, whereas the magnetic radii have a pattern largely consistent with a naive expectation based on the dressed quark masses.Comment: 7 pages, 4 figure

Proper Motion of Pulsar B1800-21

We report high angular resolution, multi-epoch radio observations of the young pulsar PSR B1800-21. Using two pairs of data sets, each pair spanning approximately a ten year period, we calculate the proper motion of the pulsar. We obtain a proper motion of mu_alpha=11.6 +- 1.8 mas/yr, mu_delta=14.8 +- 2.3 mas/yr, which clearly indicates a birth position at the extreme edge of the W30 supernova remnant. Although this does not definitively rule out an association of W30 and PSR B1800-21, it does not support an association.Comment: 13 pages, 1 color figure. Replaced with version accepted for publication in Astrophysical Journa