Persistence of Various Alfalfa Populations in South Dakota Rangeland

Inclusion of alfalfa (Medicago sativa L.) in grasslands has long been valued to increase forage production and quality. Persistence of alfalfa in semiarid rangeland has generally been poor when non‐adapted and/or conventional hay‐type cultivars are utilized, however. Demand exists for alfalfa cultivars that establish readily and persist, particularly under grazing, in semiarid rangelands. A wild population of predominantly yellow‐flowered alfalfa (Medicago sativa subsp. falcata) was found growing and reproducing naturally in the Grand River National Grassland in northwestern South Dakota. This predominantly falcata alfalfa therefore demonstrates persistence in this semiarid environment. We initiated a study in May 2006 at the SDSU Antelope Livestock & Range Field Station near Buffalo, SD to evaluate persistence and vigor of eleven alfalfa populations transplanted into mixed‐grass prairie. Populations consisted of four predominantly falcata experimental populations (three are naturally selected and locally adapted; one is artificially selected), one pure falcata experimental population, one pure falcata cultivar, two pasture‐type cultivars, and three conventional hay‐type cultivars. Greenhouse grown seedlings were transplanted on 1 m‐centers within three exclosures (35 m X 35 m) divided into two sections; one exposed to grazing, the other protected from grazing. Grazing by cattle was initiated in August 2007. During the 2008 and 2009 growing seasons, intense grazing of alfalfa plants and associated vegetation occurred monthly for 1‐2 days. Survival, height, and canopy volume of grazed and protected alfalfa plants were measured before each grazing event. Despite a harsh winter with persistent ice cover, data from May 2009 revealed that falcata‐based populations had the highest survival under grazing (mean survival = 36%). Pasture‐type cultivars and conventional hay‐type cultivars experienced substantial mortality losses under grazing (mean survival = 8%). Low mortality and high vigor of all protected plant populations indicates that grazing weakened the grazed plants, greatly increasing the risk of winterkill and winter injury. These findings reveal that environmental adaptation, in addition to a degree of grazing tolerance, is necessary for persistence under grazing in this semiarid region. Populations that exhibit high persistence under both grazing and severe winter conditions offer great potential for being utilized in the northern Great Plains

Long‐term Production and Profitability from Grazing Cattle in the Northern Mixed GrassPrairie

Conventional wisdom among rangeland professionals has been that for long‐term sustainability of grazing livestock operations, rangeland should be kept in high good to low excellent range condition. Our objective was to analyze production parameters, economic costs, returns, and profit using data generated over a thirty‐four year period (1969‐2002) from grazing a Clayey range site in the mixed‐grass prairie of western South Dakota with variable stocking rates required to maintain pastures in low‐fair, good, and excellent range condition classes. Cattle weights were measured at turnout and at the end of the grazing season. Gross income per acre was calculated by multiplying total gain per acre times price using historical National Agricultural Statistics Services feeder cattle prices. Annual variable costs were estimated from a historical yearling cattle budget developed by South Dakota State University (SDSU) agricultural economists. All economic values were adjusted to a constant dollar using the Bureau of Labor Statistics’ Consumer Price Index. Stocking rate, average daily gain, total gain, net profit, gross revenue, and annual costs per acre varied among range condition classes. Net income for low‐fair range condition ($11.18 per acre) and good range condition ($11.86 per acre) were not different, but both were greater (P \u3c 0.01) than excellent range condition ($ 9.31 per acre). Over the life of the study, real profit (adjusted for inflation) steadily increased (P \u3c 0.01) for the low‐fair and good treatments while it remained level for the excellent treatment. Neither drought nor wet springs impacted profit differently for the three treatments. These results support generally observed rancher behavior regarding range condition: to maintain their rangeland in a lower range condition than would be normally recommend by rangeland professionals. Ecosystem goods and services of increasing interest to society and associated with high range condition, such as floristic diversity, hydrologic function, and wildlife cover, come at an opportunity cost to the rancher

Mirror Dark Matter and Core Density of Galaxies

We present a particle physics realization of a recent suggestion by Spergel and Steinhardt that collisional but dissipationless dark matter may resolve the core density problem in dark matter-dominated galaxies such as the dwarf galaxies. The realization is the asymmetric mirror universe model introduced to explain the neutrino puzzles and the microlensing anomaly. The mirror baryons are the dark matter particles with the desired properties. The time scales are right for resolution of the core density problem and formation of mirror stars (MACHOs observed in microlensing experiments). The mass of the region homogenized by Silk damping is between a dwarf and a large galaxy.Comment: 9 pages, LaTex. The present version shows that atomic scattering inherent in the mirror model can solve the core density problem without the need for an extra U(1) discussed in the original version; all conclusions are unchanged. This version is accepted for publication in Phys. Rev.

The NuTeV Anomaly, Neutrino Mixing, and a Heavy Higgs Boson

Recent results from the NuTeV experiment at Fermilab and the deviation of the Z invisible width, measured at LEP/SLC, from its Standard Model (SM) prediction suggest the suppression of neutrino-Z couplings. Such suppressions occur naturally in models which mix the neutrinos with heavy gauge singlet states. We postulate a universal suppression of the Z-nu-nu couplings by a factor of (1-epsilon) and perform a fit to the Z-pole and NuTeV observables with epsilon and the oblique correction parameters S and T. Compared to a fit with S and T only, inclusion of epsilon leads to a dramatic improvement in the quality of the fit. The values of S and T preferred by the fit can be obtained within the SM by a simple increase in the Higgs boson mass. However, if the W mass is also included in the fit, a non-zero U parameter becomes necessary which cannot be supplied within the SM. The preferred value of epsilon suggests that the seesaw mechanism may not be the reason why neutrinos are so light.Comment: 19 pages, REVTeX4, 8 postscript figures. Updated references. Typos correcte

Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

ATHENA detector proposal — a totally hermetic electron nucleus apparatus proposed for IP6 at the Electron-Ion Collider

ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity. This article describes the detector design and its expected performance in the most relevant physics channels. It includes an evaluation of detector technology choices, the technical challenges to realizing the detector and the R&D required to meet those challenges

Search for heavy long-lived charged R-hadrons with the ATLAS detector in 3.2 fb(-1) of proton-proton collision data at root s=13 TeV

A search for heavy long-lived charged R-hadrons is reported using a data sample corresponding to 3.2 fb−1 of proton–proton collisions at √s = 13 TeV collected by the ATLAS experiment at the Large Hadron Collider at CERN. The search is based on observables related to large ionisation losses and slow propagation velocities, which are signatures of heavy charged particles travelling significantly slower than the speed of light. No significant deviations from the expected background are observed. Upper limits at 95% confidence level are provided on the production cross section of long-lived R-hadrons in the mass range from 600 GeV to 2000 GeV and gluino, bottom and top squark masses are excluded up to 1580 GeV, 805 GeV and 890 GeV, respectively