Now showing items 11248-11267 of 20709

    • M. v. Germany: The European Court of Human Rights Takes a Critical Look at Preventive Detention [Article]

      Alexander, Shawn; Graf, Leah; Janus, Eric (The University of Arizona James E. Rogers College of Law (Tucson, AZ), 2012)
    • Machine or Hand Cotton Picking?

      Vanvig, Andrew; St. Clair, James S.; Department of Agricultural Economics; Department of Agricultural Economics (College of Agriculture, University of Arizona (Tucson, AZ), 1954)
    • Machine Or Hand Picking?

      Holekamp, E. R.; Frost, K. R. (College of Agriculture, University of Arizona (Tucson, AZ), 1952)
    • Machine to Aid Range Reseeding

      College of Agriculture, University of Arizona (Tucson, AZ), 1967
    • Machinery for Seedbed Preparation and Seeding on Southwestern Ranges

      Anderson, D.; Swanson, A. R. (Society for Range Management, 1949-04-01)
    • Machinery Maintenance

      Pendery, Bruce M.; Rumbaugh, Melvin D. (Society for Range Management, 1992-06-01)
    • Mackenzie River Delta Chronology

      Giddings, J. L., Jr. (Tree-Ring Society, 1947-04)
    • Macro and trace mineral content of selected south Texas deer forages

      Barnes, Thomas G.; Varner, Larry W.; Blankenship, Lytle H.; Fillinger, Thomas J.; Heineman, Sharon G. (Society for Range Management, 1990-05-01)
      White-tailed deer (Odocoileus virginianus) derive the majority of their dietary mineral intake from range forages which may be deficient in one or more essential minerals. We have described the macro and trace mineral concentration of 18 shrub, 26 forb, 7 grass, and 1 cactus species, known to occur in south Texas deer diets, collected from the Chaparral Wildlife Management Area in 1974 and 1975. Within each forage class, there were no seasonal differences in calcium (Ca), sodium (Na), potassium (K), or magnesium (Mg) concentrations. Phosphorus (P) concentrations in browse were higher (P less than or equal to 0.05) during the season (0.20%) than during other seasons (0.14-0.16%). Forb P concentrations were greatest during the spring and winter periods (0.26 and 0.29%, respectively), and P levels in grasses (0.24-0.14%) decreased as the forage matured and reached senescence. Shrubs contained less P and K (P less than or equal to 0.01) than either grasses or forbs; whereas, grasses contained lower concentrations of Ca and Mg (P less than or equal to 0.01) than shrubs or forbs. Sodium concentrations did not differ among forage classes. Forbs contained greater (P less than or equal to 0.01) levels of copper (Cu) and zinc (Zn) than grasses or browse, and browse contained less iron (Fe) (P less than or equal to 0.01) than forbs or grasses. Manganese concentrations did not differ among forage classes. There were differences in mineral concentrations among species within forage class. Results suggest concentrations of all minerals except P met or exceeded minimum domestic animal requirements. Managers should provide a diversity of plant species and encourage practices that promote forb growth to provide optimum and nutritional benefits for deer.
    • Macro Economics and Cattle Ranching

      Holechek, Jerry L.; Hawkes, Jerry; Darden, Tim D. (Society for Range Management, 1994-06-01)
    • Macronutrients in soil and bromegrass after long-term N fertilization

      Harapiak, J. T.; Malhi, S. S.; Gill, K. S.; Flore, N. (Society for Range Management, 2004-03-01)
      Information on the long-term impact of repeated annual fertilizer applications of different nitrogen (N) sources on soil and plants is needed to develop sustainable grassland production systems. The concentration of macronutrients in the 0-5, 5-10, 10-15, 15-30, 30-60, 60-90 and 90-120 cm layers in a thin Black Chernozemic (Typic Boroll) soil and in bromegrass (Bromus inermis Leyss.) hay were compared after 15 annual applications of 168 and 336 kg N ha-1 as ammonium nitrate, urea, calcium nitrate, and ammonium sulphate, and a zero-N check. The concentration of NO3-N was increased by ammonium nitrate and ammonium sulphate at both N rates in most soil layers, by calcium nitrate at both N rates and by urea at 336 kg N ha-1 in the 15-60 cm soil. The accumulation of NO3-N increased with soil depth down to 60 cm, except for urea and ammonium sulphate at 168 kg N ha-1, and then it declined in deeper soil layers. The concentration of NH4-N was increased with fertilizer applications in some of the surface soil layers. The concentration of P was increased in the top 15 cm soil by ammonium nitrate and ammonium sulphate. The concentrations of Ca, Mg and K in the surface soil declined with most of the N fertilizer treatments while some treatments increased the Ca and Mg concentrations in the deeper soil layers. Increasing the N rate from 168 to 336 kg N ha-1 usually accentuated the above stated N effects on the concentration of macronutrients in the soil. The nitrate-based fertilizers caused more accumulation of NO3-N in some soil layers than the ammonium-based fertilizers. The relative increase in the concentration of NH4-N and P and the decline in the concentration of Ca, Mg and K in the soil by N addition was usually associated with the concomitant lowering of soil pH by N fertilization. In bromegrass hay, the total N concentration was increased by N fertilization but the concentration of other elements, except K, usually declined because of the dilution effect of the extra hay yield associated with N addition. Increasing the N rate from 168 to 336 kg N ha-1 further elevated the total N concentration but had no effect on the concentration of the other elements. Total N concentration in the hay tended to be greater with ammonium sulphate and ammonium nitrate than with the other 2 fertilizers. The concentration of total S was greater with ammonium sulphate than the other N fertilizers, and the concentration of P, Ca, Mg and K was not affected by the N fertilizer type. Fertilizer-induced high levels of NO3-N, NH4-N and P in soil may present potential for environmental pollution at these high N rates.
    • Macroscopic subdivision of silica aerogel collectors for sample return missions

      Ishii, H. A.; Bradley, J. P. (The Meteoritical Society, 2006-01-01)
      Silica aerogel collector tiles have been employed for the collection of particles in low Earth orbit and, more recently, for the capture of cometary particles by NASA's Stardust mission. Reliable, reproducible methods for cutting these and future collector tiles from sample return missions are necessary to maximize the science output from the extremely valuable embedded particles. We present a means of macroscopic subdivision of collector tiles by generating large-scale cuts over several centimeters in silica aerogel with almost no material loss. The cut surfaces are smooth and optically clear allowing visual location of particles for analysis and extraction. This capability is complementary to the smaller-scale cutting capabilities previously described (Westphal 2004; Ishii 2005a, 2005b) for removing individual impacts and particulate debris in tiny aerogel extractions. Macroscopic cuts enable division and storage or distribution of portions of aerogel tiles for immediate analysis of samples by certain techniques in situ or further extraction of samples suited for other methods of analysis. The capability has been implemented in the Stardust Laboratory at NASA's Johnson Space Center as one of a suite of aerogel cutting methods to be used in Stardust sample curation.
    • MACS: An Accelerator-Based Radioisotope Measuring System

      Purser, Kenneth H.; Liebert, Reuel B.; Russo, Carl J. (American Journal of Science, 1980-01-01)
      A description is given of an accelerator-based radioisotope measuring system, being supplied to the Universities of Arizona and Toronto and in part to the University of Oxford. This system will be capable of measuring 14C/12C and 14C/12C ratios in milligram samples of cracked acetylene. At present 200 micrograms of carbon obtained from cracked acetylene appears to be adequate for an isotopic ratio determination. Previous performance and new calculations indicate that a precision better than 1 percent will be achieved in a half-hour period only limited by counting statistics. A precision of 0.2 percent will be obtained in a ten-hour period. Using a carbon sample with an age greater than 60,000 years, the measured background 14C/12C ratio will be less than 0.07 percent of modern.
    • Made in the USA en español: Reading Identity in Picture Book Life Narratives

      Kanost, Laura; Kansas State University (Worlds of Words: Center for Global Literacies and Literatures (University of Arizona), 2013-06)
    • Madrean Evergreen Woodland

      Brown, David E.; Arizona Game and Fish Department (University of Arizona (Tucson, AZ), 1982)
    • Madrean Oak Woodlands Along the Arizona/Sonora Boundary

      Bahre, Conrad J.; Minnich, Richard A.; Department of Land, Air and Water Resources, University of California, Davis | Department of Earth Sciences, University of California, Riverside (University of Arizona (Tucson, AZ), 2015-05-20)
    • Magma ocean fractional crystallization and cumulate overturn in terrestrial planets: Implications for Mars

      Elkins-Tanton, L. T.; Parmentier, E. M.; Hess, P. C. (The Meteoritical Society, 2003-01-01)
      Crystallization of a magma ocean on a large terrestrial planet that is significantly melted by the energy of accretion may lead to an unstable cumulate density stratification, which may overturn to a stable configuration. Overturn of the initially unstable stratification may produce an early basaltic crust and differentiated mantle reservoirs. Such a stable compositional stratification can have important implications for the planet's subsequent evolution by delaying or suppressing thermal convection and by influencing the distribution of radiogenic heat sources. We use simple models for fractional crystallization of a martian magma ocean, and calculate the densities of the resulting cumulates. While the simple models presented do not include all relevant physical processes, they are able to describe to first order a number of aspects of martian evolution. The models describe the creation of magma source regions that differentiated early in the history of Mars, and present the possibility of an early, brief magnetic field initiated by cold overturned cumulates falling to the core- mantle boundary. In a model that includes the density inversion at about 7.5 GPa, where olivine and pyroxene float in the remaining magma ocean liquids while garnet sinks, cumulate overturn sequesters alumina in the deep martian interior. The ages and compositions of source regions are consistent with SNC meteorite data.
    • Magmatic cristobalite and quartz in the NWA 856 Martian meteorite

      Leroux, Hugues; Cordier, Patrick (The Meteoritical Society, 2006-01-01)
      Silica-rich late-stage crystallization pockets in the Martian meteorite Northwest Africa (NWA) 856 were investigated by transmission electron microscopy (TEM). The pockets occur as wedges between maskelynite laths or between maskelynite and pyroxene. They consist of elongated grains of cristobalite and quartz embedded in a silica-rich glass. Interstitial to the amorphous phase and silica minerals, a number of small accessory minerals have been identified, typical for late-stage crystallization products. They are ilmenite, tranquillityite, fayalite, troilite, baddeleyite, apatite, and chloroapatite. Cristobalite and quartz are shocked, as revealed by the occurrence of numerous amorphous lamellae. This assemblage suggests metastable dendritic crystallization under hydrous conditions. Cristobalite crystallization was probably facilitated by the presence of impurities such as Na or H2O. Our observations show that silica minerals can be formed under magmatic conditions on Mars.
    • 'Magnar’ Basin Wildrye—Germination in Relation to Temperature

      Evans, R. A.; Young, J. A. (Society for Range Management, 1983-05-01)
      Basin wildrye (Elymus cinereus) is potentially a very valuable forage species adapted to saline/alkaline range sites in the Great Basin. Poor seed fill and low germination have limited the usefulness of this species for range revegetation. The recently released cultivar 'Magnar' tends to overcome these obstacles and offers a higher potential for use of basin wildrye on rangelands. In this study we compared the germination of 'Magnar' and its sister selection accession P-15590 at 55 constant and alternating temperatures. The seeds of both selections are highly germinable with optimum regimes for temperatures centered around 20 degrees C. 'Magnar' seeds had 82% germination at moderate seedbed temperatures and 32, 28 and 37% germination at colder, warmer, or widely fluctuating seedbed temperatures, respectively. Germination of 'Magnar' seeds was most rapid at what became optimum temperature regimes for germination. Germination was increasingly delayed at extremely warm, cold, or widely fluctuating temperatures.
    • Magnesium Perchlorate as an Alternative Water Trap in AMS Graphite Sample Preparation: A Report on Sample Preparation at KCCAMS at the University of California, Irvine

      Santos, G. M.; Southon, J. R.; Druffel-Rodriguez, K. C.; Griffin, S.; Mazon, M. (Department of Geosciences, The University of Arizona, 2004-01-01)
      We present a brief discussion of sample preparation procedures at the Keck Carbon Cycle Accelerator Mass Spectrometer (KCCAMS), University of California, Irvine, and a systematic investigation of the use of Mg(ClO4)2 as an absorptive water trap, replacing the standard dry ice/ethanol cold finger in graphite sample preparation. We compare high-precision AMS measurement results from oxalic acid I and USGS coal samples using Mg(ClO4)2 under different conditions. The results obtained were also compared with those achieved using the conventional water removal technique. Final results demonstrate that the use of Mg(ClO4)2 as an alternative water trap seems very convenient and reliable, provided the Mg(ClO4)2 is replaced frequently.
    • Magnetic characterization of Cretaceous-Tertiary boundary sediments

      Villasante-Marcos, V.; Martínez-Ruiz, F.; Osete, M. L.; Urrutia-Fucugauchi, J. (The Meteoritical Society, 2007-01-01)
      Rock magnetic properties across several K-T boundary sections have been investigated to reveal any possible magnetic signature associated with the remains of the impact event at the end of the Cretaceous. Studied sections locations vary in distance to the Chicxulub structure from distal (Agost and Caravaca, Spain), through closer (ODP Hole 1049A, Blake Nose, North Atlantic), to proximal (El Mimbral and La Lajilla, Mexico). A clear magnetic signature is associated with the fireball layer in the most distal sections, consisting of a sharp increase in susceptibility and saturation isothermal remanent magnetization (SIRM), and a decrease in remanence coercivity. Magnetic properties in these sections point to a distinctive ferrimagnetic phase, probably corresponding to the reported Mg- and Ni-rich, highly oxidized spinels of meteoritic origin. At closer and proximal sections magnetic properties are different. Although there is an increase in susceptibility and SIRM associated with a rusty layer placed on top of the siliciclastic deposit in proximal sections, and with a similar limonitic layer on top of the spherule bed that defines the boundary at Blake Nose, the magnetic properties indicate a mixture of iron oxyhydroxides dominated by fine-grained goethite. Based on previous geochemical studies at Blake Nose and new geochemical and PGE abundance measurements performed in this work at El Mimbral, this goethite-rich layer can be interpreted as an effect of diagenetic remobilization and precipitation of Fe. There is not enough evidence to assert that this Fe concentration layer at proximal sections is directly related to deposition of fine meteoritic material. Magnetic, geochemical, and iridium data reject it as a primary meteoritic phase.