Potential Tetany Hazard of N-Fertilized Bromegrass as Indicated by Chemical Composition

The objective of this field experiment was to determine the effect of N fertilization on yield and chemical composition of smooth bromegrass (Bromus inermis L.) and the potential for grass tetany hazard in the northern Great Plains as indicated by chemical composition of bromegrass forage. Chemical components of forage considered in relation to the hazard of tetany (a metabolic disorder of ruminants resulting from forage with low Mg availability) were inorganic cations, organic anions, aconitate, and % total N/% total water-soluble carbohydrate ratio (N/TWSC). Soil was Parshall fine sandy loam, a pachic haploborall. Yields and chemical composition of oven dried forage from plots not previously harvested were determined at approximately 3-week intervals beginning May 9. Differences between the sum (in meq/kg) of inorganic cations (Na+, K+, Ca²+, Mg²+) and inorganic anions (Cl-, No?-, H?PO?-, SO?²-) in forage was defined as the concentration of organic anions (C-A). Mature forage yield obtained from the unfertilized check plot treatment on July 29 was only 29 and 22% of yields obtained from plot treatments fertilized with 90 and 270 kg N/ha, respectively. The K/(Ca+Mg) ratios and K concentrations increased during May and early June, resulting in a K/(Ca+Mg) ratio near or above 2.2 during June and early June in oven dried forage from fertilized treatments. Potassium, expressed as a fraction K/C of the total cations (C), accounted for 35 to 74% of the cationic charge. Fertilization with N increased total N and K concentration and K/C in the forage. As K/C increased, Mg/C and Ca/C decreased and K/(Ca+Mg) increased. Aconitate and C-A concentration correlated highly with K concentration and were increased by N fertilization. Aconitate levels exceeded 1% on May 28; the 270 kg N-treatment remained above 1% through July. Nitrogen fertilizer increased N/TWSC in spring-harvested forage, compared to unfertilized forage, and greatly accentuated the peak N/TWSC values occurring in late spring samples. This study indicated that although potential for increased forage and livestock-carrying capacity with N fertilization is tremendous, N-fertilization may result in a potential tetany hazard to ruminants. Therefore, management practices are needed which minimize tetany hazard while bromegrass yields are increased by N fertilization

School self-evaluation and its impact on teachers’ work in England

This study, based on in-depth interview data from a sample of schools in the midlands of England, offers an analysis of UK teachers’ perceptions and understandings of school self evaluation at a point when national accountability procedures have required that all schools complete and constantly update a web-based self evaluation schedule, which is then used as the basis for high stakes external inspection. School systems and cultures of self evaluation were found to be diverse, complex and school-specific. Three broad cultural categories are proposed as a heuristic to illuminate: issues of compliance and resistance, teacher motivation and behaviours, understandings of professionalism and leadership, school ethos, job satisfaction, and the use and interpretation of school level data in relation to school self evaluation

On Dark Matter Annihilation in the Local Group

Under the hypothesis of a Dark Matter composed by supersymmetric particles like neutralinos, we investigate the possibility that their annihilation in the haloes of nearby galaxies could produce detectable fluxes of $\gamma$-photons. Expected fluxes depend on several, poorly known quantities such as the density profiles of Dark Matter haloes, the existence and prominence of central density cusps and the presence of a population of sub-haloes. We find that, for all reasonable choices of Dark Matter halo models, the intensity of the $\gamma$-ray flux from some of the nearest extragalactic objects, like M31, is comparable or higher than the diffuse Galactic foreground. We show that next generation ground-based experiments could have the sensitivity to reveal such fluxes which could help us unveiling the nature of Dark Matter particles.Comment: 11 pages, 10 figures. Accepted for publication in Phys. Rev. D.; added a new paragraph on the detectability of Galactic sub-halos in our Galaxy; added a discussion on their model dependence. The relation of our results with the "CDM crisis" issue has also been adde

A rapid staining technique for the detection of the initiation of germination of bacterial spores

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75645/1/j.1472-765x.2002.01047.x.pd

Simulation techniques for cosmological simulations

Modern cosmological observations allow us to study in great detail the evolution and history of the large scale structure hierarchy. The fundamental problem of accurate constraints on the cosmological parameters, within a given cosmological model, requires precise modelling of the observed structure. In this paper we briefly review the current most effective techniques of large scale structure simulations, emphasising both their advantages and shortcomings. Starting with basics of the direct N-body simulations appropriate to modelling cold dark matter evolution, we then discuss the direct-sum technique GRAPE, particle-mesh (PM) and hybrid methods, combining the PM and the tree algorithms. Simulations of baryonic matter in the Universe often use hydrodynamic codes based on both particle methods that discretise mass, and grid-based methods. We briefly describe Eulerian grid methods, and also some variants of Lagrangian smoothed particle hydrodynamics (SPH) methods.Comment: 42 pages, 16 figures, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 12; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke

Monitoring Soil Quality to Assess the Sustainability of Harvesting Corn Stover

Harvesting feedstock for biofuel production must not degrade soil, water, or air resources. Our objective is to provide an overview of field research being conducted to quantify effects of harvesting corn (Zea mays L.) stover as a bioenergy feedstock. Coordinated field studies are being conducted near Ames, IA; St. Paul and Morris, MN; Mead, NE; University Park, PA; Florence, SC; and Brookings, SD., as part of the USDA-ARS Renewable Energy Assessment Project (REAP). A baseline soil quality assessment was made using the Soil Management Assessment Framework (SMAF). Corn grain and residue yield for two different stover harvest rates (∼50% and ∼90%) are being measured. Available soil data remains quite limited but sufficient for an initial SMAF analysis that confirms total organic carbon (TOC) is a soil quality indicator that needs to be closely monitored closely to quantify crop residue removal effects. Overall, grain yields averaged 9.7 and 11.7 Mg ha−1 (155 and 186 bu acre−1) in 2008 and 2009, values that are consistent with national averages for both years. The average amount of stover collected for the 50% treatment was 2.6 and 4.2 Mg ha−1 for 2008 and 2009, while the 90% treatment resulted in an average removal of 5.4 and 7.4 Mg ha−1, respectively. Based on a recent literature review, both stover harvest scenarios could result in a gradual decline in TOC. However, the literature value has a large standard error, so continuation of this long-term multi-location study for several years is warranted

N-body simulations of gravitational dynamics

We describe the astrophysical and numerical basis of N-body simulations, both of collisional stellar systems (dense star clusters and galactic centres) and collisionless stellar dynamics (galaxies and large-scale structure). We explain and discuss the state-of-the-art algorithms used for these quite different regimes, attempt to give a fair critique, and point out possible directions of future improvement and development. We briefly touch upon the history of N-body simulations and their most important results.Comment: invited review (28 pages), to appear in European Physics Journal Plu