Investigations and research in Nevada by the Water Resources Division, U. S. Geological Survey, 1982-83

The Water Resources Division, U.S. Geological Survey, is charged with (1) maintaining a hydrologic network in Nevada that provides information on the status of the State\u27s water resources and (2) engaging in technical water-resources investigations that have a high degree of transferability. To meet these broad objections, 26 projects were active in Nevada during fiscal year 1982 in cooperation with 36 Federal, State, and local agencies. Total funds were $3,319,455, of which State and local cooperative funding amounted to$741,500 and Federal funding (comprised of Geological Survey Federal and cooperative programs plus funds from six other Federal agencies) amounted to $2,577,955 for the fiscal year.Projects other than continuing programs for collection of hydrologic data included the following topics of study: geothermal resources, areal ground-water resources and ground-water modeling, waste disposal, prehistoric hydrology, acid mine drainage, the unsaturated zone, stream and reservoir sedimentation, river-quality modeling, flood hazards, and remote sensing in hydrology. For each project, the objectives, approach, progress in fiscal year 1982, and plans for fiscal year 1983 are described herein. A total of 26 reports and symposium abstracts were published or in press during fiscal year 1982 as an outgrowth of project work in the State

Induction of IL 2 receptor expression and cytotoxicity of thymocytes by stimulation with TCF1

We investigated the role of T cell cytotoxicity inducing factor 1 (TCF1) in the induction of a cytotoxic T cell response. We found that help-deficient thymocyte cultures supplied with saturating amounts of purified IL 2 did not develop CTL in a 5-day culture. The expression of cytotoxicity was dependent on the addition of TCF1 derived from the T cell hybridoma K15. TCF1 also induced proliferation of thymocytes in the presence of IL 2. Only the PNA- thymocyte subpopulation responded to TCF1 with proliferation and cytotoxicity in the presence of IL 2. The monokine IL 1 also induced proliferation in this subpopulation but failed to induce cytotoxicity. IL 1 was further distinguished from TCF1 by inhibition of IL 1-induced but not TCF1-induced proliferation by anti-IL 1 antibodies. In addition, using anti-IL 2 receptor antibodies (AMT 13), we showed that TCF1 in the presence of IL 2 substantially increased IL 2 receptor expression in thymocytes. IL 1 had the same effect on induction of IL 2 receptor expression as TCF1. Because some effects of IL 1 and TCF1 are distinct and some overlap, we discuss whether IL 1 and TCF1 induce different subsets of PNA- thymocytes

Second Harmonic Generation from Phononic Epsilon-Near-Zero Berreman Modes in Ultrathin Polar Crystal Films

Immense optical field enhancement was predicted to occur for the Berreman mode in ultrathin films at frequencies in the vicinity of epsilon near zero (ENZ). Here, we report the first experimental proof of this prediction in the mid-infrared by probing the resonantly enhanced second harmonic generation (SHG) at the longitudinal optic phonon frequency from a deeply subwavelength-thin aluminum nitride (AlN) film. Employing a transfer matrix formalism, we show that the field enhancement is completely localized inside the AlN layer, revealing that the observed SHG signal of the Berreman mode is solely generated in the AlN film. Our results demonstrate that ENZ Berreman modes in intrinsically low-loss polar dielectric crystals constitute a promising platform for nonlinear nanophotonic applications

Strong Coupling of Epsilon-Near-Zero Phonon Polaritons in Polar Dielectric Heterostructures

We report the first observation of epsilon near zero (ENZ) phonon polaritons in an ultrathin AlN film fully hybridized with surface phonon polaritons (SPhP) supported by the adjacent SiC substrate. Employing a strong coupling model for the analysis of the dispersion and electric field distribution in these hybridized modes, we show that they share the most prominent features of the two precursor modes. The novel ENZ-SPhP coupled polaritons with a highly propagative character and deeply sub-wavelength light confinement can be utilized as building blocks for future infrared and terahertz (THz) nanophotonic integration and communication devices

Low-temperature spin relaxation in n-type GaAs

Low-temperature electron spin relaxation is studied by the optical orientation method in bulk n-GaAs with donor concentrations from 10^14 cm^{-3} to 5x10^17 cm^{-3}. A peculiarity related to the metal-to-insulator transition (MIT) is observed in the dependence of the spin lifetime on doping near n_D = 2x10^16 cm^{-3}. In the metallic phase, spin relaxation is governed by the Dyakonov-Perel mechanism, while in the insulator phase it is due to anisotropic exchange interaction and hyperfine interactio

Manipulation of the Spin Memory of Electrons in n-GaAs

We report on the optical manipulation of the electron spin relaxation time in a GaAs based heterostructure. Experimental and theoretical study shows that the average electron spin relaxes through hyperfine interaction with the lattice nuclei, and that the rate can be controlled by the electron-electron interactions. This time has been changed from 300 ns down to 5 ns by variation of the laser frequency. This modification originates in the optically induced depletion of n-GaAs layer

Frog Prince transposon-based RNAi vectors mediate efficient gene knockdown in human cells

We have developed a stable RNA interference (RNAi) delivery system that is based on the Frog Prince transposable element. This plasmid-based vector system combines the gene silencing capabilities of H1 polymerase III promoter-driven short hairpin RNAs (shRNA) with the advantages of stable and efficient genomic integration of the shRNA cassette mediated by transposition. We show that the Frog Prince-based shRNA expressing system can efficiently knock down the expression of both exogenous as well as endogenous genes in human cells. Furthermore, we use the Frog Prince-based system to study the effect of knockdown of the DNA repair factor Ku70 on transposition of the Sleeping Beauty transposon. Transposon-mediated genomic integration ensures that the shRNA expression cassette and a selectable marker gene within the transposon remain intact and physically linked. We demonstrate that a major advantage of our vector system over plasmid-based shRNA delivery is both its enhanced frequency of intact genomic integration as well as higher target suppression in transgenic human cells. Due to its simplicity and effectiveness, transposon-based RNAi is an emerging tool to facilitate analysis of gene function through the establishment of stable loss-of-function cell lines

Coherent nonlinear optical spectroscopy of single quantum dot excited states

We report a coherent nonlinear optical signature of the excited states of two quantum dots. By comparing the nonlinear spectra with the linear photoluminescence excitation spectrum, a clear identification of excited states is possible. © 2004 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70297/2/APPLAB-84-11-1928-1.pd