Response to Selection for Reduced Grass Tetany Potential in Crested Wheatgrass

Grass tetany (hypomagnesemia) has caused substantial economic losses in ruminant animals grazing crested wheatgrass (Agropyron spp.) and other cool-season (C3) grasses. This malady is most prevalent in early lactating animals grazing forage that is deficient in Mg, Ca, and carbohydrates and with high levels of K. The K/(Ca + Mg) ratio expressed as moles of charge is often used to estimate the grass tetany potential of forage samples. Previous studies have shown that heritable variation exists in crested wheatgrass populations for traits associated with grass tetany, and research was conducted to determine the genetic response to selection for these traits. Selections were made during 1985 from two crested wheatgrass breeding populations in Utah (`I-28' and Hycrest) based on a reduced grass tetany potential (RTP) index, which incorporates the K/(Ca + Mg) ratio along with concentrations of Ca, Mg, and K. Mean values for the K/(Ca + Mg) were reduced by 5% in 1-28 and 11% in Hycrest after one cycle of selection. Narrow-sense heritability values based on actual genetic advance and parent-progeny regression ranged from 0.62 to 0.82 in analyses of data combined across two sampling dates and two years (1988 and 1989). Genetic response to selection on the basis of RTP index was closely associated with the K/(Ca + Mg) ratio and concentrations of Ca and Mg but not with levels of K. Correlations between the K/(Ca + Mg) ratio and crude protein content and digestibility suggested that selection for RTP would likely be accompanied by improved forage quality in the Hycrest breeding population

Analysis of trace elements in forages by near infrared reflectance spectroscopy

Use of near infrared reflectance spectroscopy (NIRS) for elemental analysis has been limited to a few elements including Ca, P, K, and Mg. However, other elements are of interest in the agricultural industry. Therefore, NIRS spectra were collected on forage samples consisting of tall fescue (Festuca arundinacea Schreb.), crested wheatgrass (Agropyron cristatum and A. desertorum), and alfalfa (Medicago sativa L.). Elemental concentrations of Ba, Li, Mo, Ni, Pb, V, Al, S, and Si were determined by ICP (Inductively Coupled Argon Plasma) analysis while selenium (Se) was determined by fluorometry. The elemental analyses were regressed against NIRS apparent absorption from 1100 to 2500 nm at 2-nm increments. Coefficients of variation /CV = (standard error of performance / the mean from the chemical procedure) X 1001 ranged from a high of 211% for Li in crested wheatgrass to 11% for S in alfalfa. Determination of Ba, Li, Mo, Ni, Pb, and V exhibited enough inconsistency in CVs among the three forages to preclude their determination with NIRS. Aluminum and S appear to be present in an organic form that NIRS is able to detect (CV = 22 and 15, 21 and 12, and 28 and 11%, for tall fescue, crested wheatgrass, and alfalfa, respectively). Silica exhibited slightly more variation than S or Al, with alfalfa having the highest CV (49%). Selenium was only determined on a tall fescue population with a CV = 27%. Using the statistical values as parameters indicative of NIRS utility, it appears that Al and S are the only elements in this group of minerals that can be determined with NIRS for these forage types

Mineral analysis of forages with near infrared reflectance spectrosopy

Mineral concentration data could easily be generated by near infrared reflectance spectroscopy (NIRS) while determining quality parameters in forage samples. However, which minerals can be analyzed and why they can be determined has not been documented adequately. Therefore, NIRS spectra were collected on 200 samples of crested wheatgrass (Agropyron spp.), 203 tall fescue (Festuca arundinacea Schreb.), and 59 alfalfa (Medicago sativa L.) hays. Concentrations of Na, K, Ca, P, Mg, Fe, Mn, Cu, and Zn, as determined by atomic absorption, and calculated values of the Ca/P, K/Mg, and K/(Ca + Mg) ratios were regressed against reflectance values measured in 2-nm increments between 1100 and 2500 nm for each sample. Approximately one half of the samples in each forage set was used to develop the calibration equations, while the other half was used to validate the equations. The coefficients of variation [CV = (standard error of analysis ÷ the mean)X 100] generally ranged from 10 to 20% for K, Mg, Ca, and P concentrations in each forage type. The Ca/P ratio in alfalfa was determined with a CV of 18%. The CV values of other minerals and mineral ratios generally exceeded 20%. Chlorophyll and some inorganic salts and organic-acid salts of Ca, Mg, and K were scanned with NIRS for wavelength comparisons with those wavelengths used to determine mineral concentrations in forages. Some of the wavelengths used in the equations for Ca, K, and Mg were related to peaks and changes in slope observed in chlorophyll and organic-acid salts of Ca, K, and Mg, suggesting that NIRS is indirectly measuring these minerals by their association with organic molecules. Accurate use of NIRS to determine mineral cation composition in forages appears limited to certain major minerals (Ca, P, K, and Mg)

Seasonal trends in herbage yield and quality of Agropyrons

Crested wheatgrasses (Agropyron spp.) are grown on 6 million ha in the U.S. and Canada, where they provide excellent early-season forage, but lose nutritional quality by midsummer. Some producers believe that A. fragile maintains its quality longer than other crested wheatgrasses. This study compared herbage yield and quality of 3 A. fragile entries with A. desertorum, A. cristatum, 1-28 (induced tetraploid of A. cristatum), and the hybrid 'Hycrest'. Entries were established near Logan, Ut., on 1-m spacings. Herbage yield and quality were determined in year 2 and 3 at vegetative, boot, flower, seed ripe, and post-seed-ripe maturity stages (harvests 1 through 5) and on regrowth following the vegetative and boot-stage harvests. All entries flowered within 1 to 2 days of each other. Dry-matter yield increased for all grasses, but digestibility (IVDMD), crude protein, and elemental concentrations declined with maturity. Mean IVDMD values for all grasses were 741,642,534,485, and 444 mg g-1 for harvests 1 through 5 and 490 and 560 mg g-1 for the regrowth following harvest 1 and 2. The A. fragile entries had higher N, Ca, P, and Ca/P, but lower yield, IVDMD, and grass tetany potential values than other Agropyrons. Contrary to expectations, IVDMD of A. fragile decreased to 500 mg g-1 , 6 to 11 days earlier than for the other Agropyrons. The 1-28 and Hycrest entries had higher yield, IVDMD, K, and grass tetany risk and lower N, Ca, P, and Ca/P than the other Agropyrons

Observed photodetachment in parallel electric and magnetic fields

We investigate photodetachment from negative ions in a homogeneous 1.0-T magnetic field and a parallel electric field of approximately 10 V/cm. A theoretical model for detachment in combined fields is presented. Calculations show that a field of 10 V/cm or more should considerably diminish the Landau structure in the detachment cross section. The ions are produced and stored in a Penning ion trap and illuminated by a single-mode dye laser. We present preliminary results for detachment from S- showing qualitative agreement with the model. Future directions of the work are also discussed.Comment: Nine pages, five figures, minor revisions showing final publicatio

Ecological Invasion, Roughened Fronts, and a Competitor's Extreme Advance: Integrating Stochastic Spatial-Growth Models

Both community ecology and conservation biology seek further understanding of factors governing the advance of an invasive species. We model biological invasion as an individual-based, stochastic process on a two-dimensional landscape. An ecologically superior invader and a resident species compete for space preemptively. Our general model includes the basic contact process and a variant of the Eden model as special cases. We employ the concept of a "roughened" front to quantify effects of discreteness and stochasticity on invasion; we emphasize the probability distribution of the front-runner's relative position. That is, we analyze the location of the most advanced invader as the extreme deviation about the front's mean position. We find that a class of models with different assumptions about neighborhood interactions exhibit universal characteristics. That is, key features of the invasion dynamics span a class of models, independently of locally detailed demographic rules. Our results integrate theories of invasive spatial growth and generate novel hypotheses linking habitat or landscape size (length of the invading front) to invasion velocity, and to the relative position of the most advanced invader.Comment: The original publication is available at www.springerlink.com/content/8528v8563r7u2742

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13