The vertical distribution of iron stable isotopes in the North Atlantic near Bermuda

Seawater dissolved iron isotope ratios (δ^(56)Fe) have been measured in the North Atlantic near Bermuda. In a full-depth profile, seawater dissolved δ^(56)Fe is isotopically heavy compared to crustal values throughout the water column (δ^(56)Fe_(IRMM-014) = +0.30‰ to +0.71‰). Iron isotope ratios are relatively homogenous in the upper water column (between +0.30‰ to +0.45‰ above 1500 m), and δ^(56)Fe increases below this to a maximum of +0.71‰ at 2500 m, decreasing again to +0.35‰ at 4200 m. The δ^(56)Fe profile is very different from the iron concentration profile; in the upper water column [Fe] is variable while δ^(56)Fe is relatively constant, and in the deeper water column δ^(56)Fe varies while [Fe] remains relatively constant. The δ^(56)Fe profile is also not well correlated with other hydrographic tracers in the North Atlantic such as temperature, salinity, or the concentrations of oxygen, phosphate, silica, and CFC-11. The dissimilarity between δ^(56)Fe profiles and profiles of [Fe] and other hydrographic tracers shows that Fe isotope ratios provide a unique sort of information about ocean chemistry, and they suggest that Fe isotopes may therefore be a valuable new tool for tracing the global sources, sinks, and biogeochemical cycling of Fe

Precision study of positronium and precision tests of the bound state QED

Despite its very short lifetime positronium provides us with a number of accurate tests of the bound state QED. In this note a brief overview of QED theory and precision experiments on the spectrum and annihilation decay of the positronium atom is presented. Special attention is paid to the accuracy of theoretical predictions.Comment: A talk presented at 9th International Workshop on Slow Positron Beam Techniques for Solids and Surfaces (SLOPOS), Dresden, 200

Composite Skyrme Model with Vector Mesons

We study the composite Skyrme model, proposed by Cheung and G\"{u}rsey, introducing vector mesons in a chiral Lagrangian. We calculate the static properties of baryons and compare with results obtained from models without vector mesons.Comment: LaTeX, 9 pages, 3 figures, to be published in Phys. Rev.

The Proficiency Illusion

Examines the tests states use to measure academic progress under the No Child Left Behind Act. Explores whether expectations for proficiency in reading and mathematics are consistent between states

The historical geography of extinct towns in Mississippi

Towns are places of agglomerated settlement having economic interaction with a supporting hinterland. While many nucleated settlements were increasing in population, others were losing population and becoming extinct, Between 1830 and 1969, 262 towns became extinct in Mississippi, The spatial distribution of extinct towns in north Mississippi reflect changes in the cotton based economy, while those in south Mississippi reflect the exhaustion of timber resources. Towns are defined to include a threshold population, functions, legality, and vernacular usage. A functional grouping of towns simplified investigation into the spatial and temporal interaction of towns with their hinterlands. Seventy-one per cent of the extinct towns had functioned as trade centers, and are divided into typical, river port, railroad, and county seat towns. Twenty-nine per cent of the extinct towns functioned as industrial towns, either manufacturing or sawmill towns. Mississippi was settled largely by persons interested in the production of cotton, which was adapted to cultivation on any scale and was the mainstay of the economy, Antebellum planters marketed cotton and made purchases through factors located in cities outside Mississippi and had no interest in supporting local commercial developments, After 1865 cotton production occurred under the share-tenant and crop lien systems, The crop lien was a self-defeating credit system that held farmers captive and deprived trade towns of their commercial gain. The size of towns was also influenced by a dispersal of urban functions and by saturation of an area with towns, railroad stations, and riverboat landings. At the height of a town\u27s prosperity, its population averaged between 150 and 300 persons. Economic development in Mississippi proceeded with a remarkable absence of manufacturing until the lumber era of 1880 to 1920. Lumbering was responsible for peopling the sparsely inhabited Piney Woods region and was performed by persons residing in towns that grew up around company owned sawmills cutting in excess of 15,000,000 board feet annually. The same forces that had influenced the location of new towns and had shaped their expansion and growth, gave rise to competition, differential growth, and the resultant decline of many centers after 1920. County seat towns acquired an additional element of centrality when the state highway system was designed to connect with all county seats. The external economics achieved by merchants in county-seat towns absorbed the trade of smaller places. Several conditions contributed to the demise and extinction of towns in Mississippi. Adjustments in settlement sites after the initial surge of settlers caused some towns to disappear. The loss of key local leadership inadvertently encouraged prospective merchants to seek new sites. Farmers tended to rely on the services and goods offered in county seat town\u27s as the range of their needs increased. After 1940 the economic base of many towns was undermined as tenancy declined and farms were consolidated. Railroads and highways interjected an element of competition between towns, and those at less favored locations declined, The decision to relocate county seats often led to the demise of towns

Oral History Interview: Nellie G. Adkins

This interview is one of a series conducted concerning West Virginia Vietnam veterans. In this interview, Nellie Adkins discusses: her marriage and her life before marriage; dating; detailed information about her husband serving in the Vietnam War; a brief mention of Robert C. Byrd; the Christmas before her husband left for Vietnam; her husband returning home; a small section on cultural perceptions of Vietnam veterans; her family life during the war; letters to and from home during the war; a small amount of information about Operation Iraqi Freedom; a brief section on her perceptions of the Vietnam War; and other topics.https://mds.marshall.edu/oral_history/1602/thumbnail.jp

alpha^2 corrections to parapositronium decay: a detailed description

We present details of our recent calculation of alpha^2 corrections to the parapositronium decay into two photons. These corrections are rather small and our final result for the parapositronium lifetime agrees well with the most recent measurement. Implications for orthopositronium decays are briefly discussed.Comment: 18 pages, late

The quantization of exotic states in SU(3) soliton models: A solvable quantum mechanical analog

The distinction between the rigid rotor and Callan-Klebanov approaches to the quantization of SU(3) solitons is considered in the context of exotic baryons. A numerically tractable quantum mechanical analog system is introduced to test the reliability of the two quantization schemes. We find that in the equivalent of the large N_c limit of QCD, the Callan-Klebanov approach agrees with a numerical solution of the quantum mechanical analog. Rigid rotor quantization generally does not. The implications for exotic baryons are briefly discussed.Comment: 8 pages; 3 figures; minor corrections; reference adde

The Single Photon Annihilation Contributions to the Positronium Hyperfine Splitting to Order meα6m_e\alpha^6

The single photon annihilation contributions for the positronium ground state hyperfine splitting are calculated analytically to order $m_e\alpha^6$ using NRQED. Based on intuitive physical arguments the same result can also be determined by a trivial calculation using results from existing literature. Our result completes the hyperfine splitting calculation to order $m_e\alpha^6$. We compare the theoretical prediction with the most recent experimental measurement.Comment: 8 pages, latex, two eps figures include

Recoil corrections in the hydrogen isoelectronic sequence

A version of the Bethe-Salpeter equation appropriate for calculating recoil corrections in highly charged hydrogenlike ions is presented. The nucleus is treated as a scalar particle of charge Z, and the electron treated relativistically. The known recoil corrections of order $m^2/M(Z\alpha)^4$ are derived in both this formalism and in NRQED