Now showing items 7066-7085 of 14780

    • The hydrology of Aravaipa Creek, southeastern Arizona

      Ellingson, Charles Thurston.; Evans, Daniel D. (The University of Arizona., 1980)
      The hydrologic system responsible for the perennial flow of Aravaipa Creek in southeastern Arizona consists of a basin filled with sediments and ground water. Ground-water flow through the basin sediments converges at the entrance of Aravaipa Canyon where much of it is forced to the surface due to a restriction in the cross-sectional area of the unindurated sediments. By applying Darcy's law, these sediments are found to have a hydraulic conductivity of up to 1,300 feet/day. The data used in the analysis show that Aravaipa Creek attains its full discharge within 2 miles of the canyon entrance due to a gradual reduction in the transmissivity of the sediments. Precipitation over the watershed is divided quantitatively into evapotranspiration, stream discharge, and pumpage. Ten years of streamflow data divided into base flow and storm runoff show that 8,500 acrefeet/ year become base flow due to ground-water runoff from the valley aquifer. Recharge in the Aravaipa aquifer equals discharge. The discharge, Aravaipa Creek base flow plus pumpage, is 11,600 acre-feet/year, or 2.4 percent of total precipitation. Streamflow statistics, water quality, and current water use are documented, and suggestions for further research are made.

      Wucinich, Regina. (The University of Arizona., 1984)
    • The hydrometallurgical extraction of transition metals from ferromanganese nodules

      Burzminski, Michael Joseph, 1953- (The University of Arizona., 1978)
    • Hydrophobic partitioning of the bacteriophage MS-2

      Bales, Roger C.; Gerba, Charles P.; Kroeger, Thomas William, 1952- (The University of Arizona., 1989)
      In batch experiments at pH's 5 and 7, the partitioning of MS-2 between water and silica (unbonded) was compared with the partitioning between water and silica with 6.5 percent of the surface covered by hydrophobic C18 chains (bonded). The roles of double-layer and van der Waals forces in partitioning were explored by modeling the potential energies of interaction. MS-2 adsorption to unbonded silica was negligible at pH 7, but did occur at pH 5. Adsorption was independent of pH with the bonded silica and approximately 2.6 orders of magnitude greater than the unbonded at pH 5, suggesting the importance of hydrophobic partitioning. The total potential energies of interaction, which closely approach the pH-independent van der Waals potentials, are similar in magnitude for all pH's or silica types, and have no positive (repulsive) values. The insignificant contribution of the double-layer potentials suggests that these pH-dependent forces may not account for the pH-dependent adsorption observed with the unbonded silica.
    • Hydrothermal alteration of intrusive igneous rocks in the Eureka mining district, Nevada

      Langlois, Joseph David, 1946- (The University of Arizona., 1971)
    • Hydrothermal alteration of volcanic cover rocks, Tintic District, Utah

      Brannon, Charles Andrew (The University of Arizona., 1982)
    • Hydrothermal metasomatic banding in alpine-type peridotites

      Gottschalk, Richard Robert (The University of Arizona., 1979)
    • Hydrothermally altered basalts from the Mariana Trough

      Trembly, Jeffrey Allen (The University of Arizona., 1982)
    • Hydroxylation of aromatic compounds by a synthetic analog of an enzyme system

      Michelson, Malvin Jay, 1933- (The University of Arizona., 1957)
    • The hyoid apparatus of nin-primaried oscinine birds

      George, William Gordon, 1925- (The University of Arizona., 1958)
    • Hyperconjugation effects in substituted cyclopropyl methyl ketones

      Lofquist, Robert Alden, 1929- (The University of Arizona., 1957)
    • Hyperconjugation in the alkyl substituted cyclopropyl methyl ketones

      Bice, Vernon Melvin, 1921- (The University of Arizona., 1949)
    • Hyperfine structure in the microwave spectra of the iodine fluorides iodine heptafluoride and iodine pentafluoride and of the weakly bound complex hydrochloric acid...nitrous oxide

      Shea, James Christopher, 1964- (The University of Arizona., 1989)
      A pulsed-beam fourier transform microwave spectrometer was used to measure the rotational spectra of iodine heptafluoride, iodine pentafluoride, and the weakly bound complex, HCl...NNO. For IF7, only five rotational transitions were observed, and no resolvable hyperfine structure was detected. Based on this data, the A, B, and C rotational constants were determined to be 1746(3) MHz, 1732.0(8) MHz, and 1553.0(2) MHz, respectively. The existence of a pure rotational spectrum confirms that this molecule undergoes polar distortions. Twenty-two hyperfine components of the IF5 spectrum were recorded. The B rotational constant for this molecule was determined to be 2727.421(3) MHz, and the quadrupole coupling constant was found to be 1069.35(13) MHz. Though the work is still in progress on HCl...NNO, nine transitions have been recorded. In addition, five transitions have been recorded for an apparent trimer species composed of HCl, NNO, and an as yet unidentified third species.

      Hayashi, Satomi; Wung, Shu-Fen; Wung, Shu-Fen; Ritter, Leslie; Merkle, Carrie (The University of Arizona., 2003)
      This comprehensive literature review focuses on homocysteine, gene polymorphisms related to homocysteine metabolism and their relationship to coronary artery disease (CAD). Currently, CAD is known as a multifactorial genetic disease, resulting from complex interactions between genetic factors and various environmental influences. In recent years, tremendous knowledge about the hereditary aspect of CAD has been gained, including an understanding of CAD as a multifactorial condition resulting from complex interactions between genetic factors and various environmental influences that trigger, accelerate, or exacerbate the disease process. Among the risk factors for CAD, hyperhomocysteinemia has been recognized for its relation to atherosclerotic alterations in the vessels. In addition, gene polymorphisms in methylene - tetrahydrofolate reductase (MTHFR), methionine synthase reductase (MTRR), methionine synthase (MS), and cystathionine ß - synthase (CßS), which are involved in homocysteine metabolism, have been identified as a result of advances in genetic research related to cardiovascular pathophysiology. In particular, the results of recent salient studies have provided evidence of significant association of these genetic polymorphisms and CAD in Japanese and part of European populations but not in the United States, Australian, and part of European populations. This disparity may explain the variation of prevalence of CAD among different populations. Potential gene - environment interactions may elevate homocysteine levels and increase the risk of CAD. This discussion includes the pathogenesis of hyperhomocysteinemia, definitions of normal and elevated homocysteine levels, the physiological background of homocysteine metabolism, polymorphisms of genes involved in homocysteine metabolism from the perspective of CAD risk, and implications for nursing practice based on emerging information regarding hyperhomocysteinemia as a risk factor for CAD. Findings from these recent studies are important for nurses, clinicians, and researchers to be able to incorporate cardiovascular genetic information in their practice and research and provide more adequate care to reduce the risk for CAD and improve patient outcomes.
    • Hypersensitive and immune response in rabbits to 2,4-dinitrophenyl compounds

      Cozine, William Samuel, 1938- (The University of Arizona., 1965)
    • Hypogene alteration at the Esperanza Mine, Pima County, Arizona

      Smith, Verl Leon, 1943- (The University of Arizona., 1975)
    • Hypoxic/aglycemic stress alters blood-brain barrier transport systems

      Davis, Thomas P.; Hom, Sharon; Larson, Douglas F.; Sethi, Gulshan K. (The University of Arizona., 1999)
      Increased cerebrovascular permeability is an important factor responsible for the development of ischemic brain injury and edema formation associated with stroke pathophysiology. Extensive studies of stroke research have centered primarily on the response of neurons and astrocytes to hypoxic or ischemic insult. The response of cerebral capillary endothelial cells to hypoxia is not well understood. Damage to the blood-brain barrier (BBB) induced by hypoxia/ aglycemia may influence BBB permeability and transport mechanisms, thereby contributing to the development and severity of stroke. The development of a low flow in situ brain perfusion model was used in this study to illustrate the effect of ischemia/hypoperfusion coupled with hypoxia and aglycemia on BBB transport mechanisms. Three transport markers were used in various combinations of low flow, hypoxia, and aglycemia to characterize BBB transport mechanisms. The results of this study suggest BBB basal permeability is not com promised during low flow perfusion, however in the presence of hypoxia/ aglycemia, a significant change in BBB permeability is observed among the three transport markers. Thus, the effects of ischemia as produced by low flow, hypoxia, and aglycemia alter BBB permeability due to the probable impaired action of many transport systems under these adverse conditions.