UScholar Works
 
Filters: School Or College: "College of Science" Collection: "ir_uspace"
151 - 175 of 1,952
Number of results to display per page
CreatorTitleDescriptionSubjectDate
151 Vardeny, Zeev ValentineOptical studies of excess carrier recombination in α-Si:H: evidence of dispersive diffusionRelaxation of photoinduced optical absorption following pulsed laser excitation was measured between 0.5 pis and 10 ms in doped and undoped a-Si:H as a function of temperature. The recombination was found to be bimolecular diffusion limited. The diffusion coefficient of the excess carriers is time ...Hydrogenated amorphous silicon; a-Si:H; Excess carrier recombination; Dispersive diffusion1980-05
152 Capecchi, Mario R.High efficiency transformation by direct microinjection of DNA into cultured mammalian cells.Direct microinjection of DNA by glass micropipettes was used to introduce the Herpes simplex virus thymidine kinase gene into cultured mammalian cells. When DNA was delivered directly into the nuclei of LMTK-, a mouse cell line deficient in thymidine kinase activity, 50--100% of the cells expressed ...Cell Nucleus; Cytoplasm; DNA, Viral; Microinjections; Recombination, Genetic1980-11-22
153 Mattis, Daniel C.Improved Landau-Ginzburg equation near surfaces of solidsWe study the order parameter near the surface for an Ising model. Applications to the lattice gas, alloy problem, and ferromagnetism are noted. Away from Tc our equations differ from the Landau-Ginzburg results due to an additional nonlinear, term which can substantially affect the order parameter...Landau-Ginzburg equation; Boundary conditions1980-12
154 Mattis, Daniel C.; Sutherland, BillStrange solutions to field theories in one spatial dimensionMany models of interacting particles rely heavily for their solution on restriction to one-dimensional motion and a linearized kinetic energy. We examine this in detail, and find that the linearization can lead to patently strange and possible spurious solutions in first quantization. The usual, co...Eigenstates; Field theories1981
155 Ailion, David CharlesNature of Ag+ self-diffusion in AgFMeasurements of the nuclear magnetic resonance (NMR) dipolar relaxation times T w and T i (51°) have been made on the 1 9 F resonance in AgF powder over the temperature range 60-300 K. Also the technique of Stokes and Ailion for detecting the diffusion of weakly magnetic spins has been verified f...NMR; Nuclear magnetic resonance; Diffusion; Ionic conductivity1981
156 Vardeny, Zeev ValentineRecombination kinetics in ?-Si:HMort et al.1 reinterpreted our data on the relaxation of photoinduced absorption (PA) in a-Si:H. 2 We want to show that the proposed interpretation contradicts one basic feature of the data while our original interpretation is in good agreement with experiment.Hydrogenated amorphous silicon; a-Si:H; Recombination kinetics; Photoinduced absorption; Decay; Relaxation1981
157 Vardeny, Zeev ValentineOptical picosecond studies of carrier thermalization in amorphous siliconThermalization of photogenerated hot carriers in a-Si, a-Si:H and a-Si:H:F was studied using the pump and probe method with subpicosecond resolution. The process is optically observable because the absorption cross-section of the hot carriers depends on their excess energy. It was found that the en...Carrier thermalization; Amorphous silicon; Frohlich interaction1981
158 Olivera, Baldomero M.; Hillyard, David R.Pyridine nucleotide cycle: studies in Escherichia coli and the human cell line D98/AH2Different metabolic steps comprise the pyridine nucleotide cycles in Escherichia coli and in the human cell line HeLa D98/AH2. An analysis of the "P-labeling patterns in vivo reveals that in E. coli, pyrophosphate bond cleavage of intracellular NAD predominates, while in the human cell line, cleava...Nicotinic acid; Turnover cycle; DNA ligation; Nicotinamide1981
159 Potts, Wayne K.Emigration behavior of Clark's NutcrackerEruptive movements of the Clark's Nutcracker (Nucifraga columbiana) were observed during the late summer and fall of 1977, 1978 and 1979 in northern Utah and adjacent states. Over 2,000 emigrating nutcrackers were seen during these periods. Eruptions began in mid to late August, about the time nutcr...Breeding range; Flocks; Observations1981
160 Olivera, Baldomero M.; Gray, William RobertPeptide toxins from Conus geographus venomThe biochemical characterization of three highly toxic peptides from the venom of the marine snail Conus geographus is described in this report. These peptides cause their potent activity by inhibition of the postsynaptic terminus of the vertebrate neuromuscular junction. The relatively small size o...Conus geographus; Venom; Conotoxins; Neurotoxins1981
161 Armentrout, Peter B.Electron impact ionization cross section of metastable N2(A Σu+)Extensive studies of electron impact cross sections have been carried out both experimentally and theoretically for a number of ground state atoms and molecules.1 In general, as the electron energy is increased, such cross sections rise from a threshold at the ionization potential to a peak at an e...Ion beam; Nitrogen1981
162 Symko, Orest GeorgeEffect of RKKY interactions on the magnetization of dilute magnetic alloys with hcp hostsThe magnetization due to the presence of magnetic impurities dissolved dilutely in nonmagnetic H.C.P. host metals has been calculated assuming a fine structure splitting by an axially symmetric crystal field and an RKKY interaction between the impurities. To compute the RKKY contribution, the inte...RKKY interactions; Dilute magnetic alloys; HCP hosts; MgMn; ZnMn1981
163 Golden, Kenneth M.Modeling of anisotropic electromagnetic reflection from sea iceThe contribution of brine layers to observed reflective anisotropy of sea ice at 100 MHz is quantitatively assessed, and a theoretical explanation for observed reflective anisotropy is proposed in terms of anisotropic electric flux penetration into the brine layers. The sea ice is assumed to be a st...Brine; Anisotropy; Polarization1981
164 Miller, Joel StevenOptical properties of cesium tetracyanoquinodimethanide, Cs2(TCNQ)3Room-temperature polarized reflectance measurements have been made on cesium tetracyanoquinodimethanide, Cs2(TCNQI3, over the frequency range between the far infrared and the near ultraviolet. The optical properties of the compound were obtained by Kramers-Kronig analysis. These properties are dom...Electrons; Lattice; Molecules1981
165 Vardeny, Zeev ValentineRelaxation of photoinduced sub-bandgap absorption in a-Si:HThe decay of photoinduced sub-bandgap absorption (PA) following pulsed excitation was studied in the temperature range 80 - 305K, in a-Si:H samples prepared by glow discharge and sputtering. The decay was interpreted in terms of bimolecular diffusion limited recombination involving dispersive trans...Photoinduced absorption; Sub-bandgap absorption; Glow discharge; Sputtering; Decay1981
166 Armentrout, Peter B.Cobalt carbene ion: reactions of Co+ with C2H4, cyclo-C3H6 and cyclo-C2H4OAn ion beam apparatus is employed to study the formation of the cobalt carbene ion, CoCH2+. This ion is produced in the endothermic reaction of cobalt ions with ethene and cyclopropane and in an exothermic reaction with ethylene oxide. A model is proposed to account for the dependence of experimenta...Cobalt carbine; Ion beam; Bond dissociation energy; Reaction cross section; Endothermic reactions1981
167 Ailion, David CharlesEvidence for elastic disorder in the elastically ordered phase of KCNWe have obtained evidence from 1 3C NMR measurements that the CN~ ion in the elastically ordered phase of KCN is misoriented slightly with respect to the orthorhombic b axis. This misorientation varies randomly over the lattice, averaging to zero on a macroscopic scale. The misorientations are mani...Potassium cyanide; Anisotropy; Orthorhombic crystal; NMR; Nuclear magnetic resonance1981
168 Parkinson, John StansfieldGenetics of bacterial chemotaxisMany types of motile bacteria are capable of detecting and responding to changes in their environment. Phototactic, chemotactic and thermotactic movements in bacteria are similar to more complex behaviours seen in higher organisms, and constitute useful model systems for investigating the molecular ...Bacterial chemotaxis1981
169 Mattis, Daniel C.Eigenfunction localization in dilute lattices of various dimensionalitiesAs a fraction of bonds p is removed from a lattice, we find a threshold PQ above which all eigenstates are nonpropagating (Anderson localized). This occurs well before the classical percolation threshold. For example, in two dimensions where the classical threshold is pc = 1/2 , we find PQ = 0.Eigenstates; Dilute lattices1981-05
170 Vardeny, Zeev ValentineHot-carrier thermalization in amorphous siliconThermalization of photoinduced carriers in a-Si and α-Si:H was studied with use of sub-picosecond-pump and probe techniques with parallel and perpendicular polarizations. The underlying process was identified as hot-carrier absorption whose cross section increases with the carrier excess energy. T...Amorphous silicon; Thermalization; Photoinduced carriers; Frohlich interaction1981-05
171 Vardeny, Zeev ValentinePhonon polariton study of CuCl1-x BrxThe optical-phonon spectrum of CuCI-x Brx at low temperature is very unusual in regard to many of its properties. Despite the apparent two-mode behavior our measurements illustrate anomalies in the Raman intensity and temperature-induced frequency shift, as well as in the oscillator strengths yiel...Cuprous halides; CuCl1-x Brx1981-08
172 DeTar, CarletonQuark-bag model with low-energy pion interactions. II. ApplicationThe hybrid pion-quark-bag model discussed in I is applied to a calculation of masses, pion couplings, and other parameters of various light hadrons in an effort to determine the extent to which the bag parameters must be modified in the presence of pion interactions. Corrections for the finite spr...Bag models; Quark bag; Chiral symmetry; Pion field; Nucleons1981-08
173 DeTar, CarletonQuark-bag model with low-energy pion interactions. I. TheoryA standard method for restoring chiral symmetry in the bag model is to introduce an explicit external pion field. Questions of the consistency and compatibility of this method with the assumptions of the static-cavity approximation of the bag model are discussed. An approximate version of the mode...Bag models; Quark bag; Chiral symmetry; Pion bag; Pion field1981-08
174 Sokolsky, PierreMeasurement of elastic νμ and ν̄μ scattering on protonsWe have measured elastic vµ and vµ scattering on protons at the Brookhaven National Laboratory Alternating Gradient Synchrotron. We find RNC = σ (νµp → vµp)/σ (vµp -* vµp) = 0.44 ±0.12 and Rvµ = σ (vµp → vµp)/σ (vµn → µ-p) =0.11 ±0.03. The elastic Q2 distribution is in good a...1981-09
175 Mattis, Daniel C.; Sutherland, BillAmbiguities with the relativistic δ-function potentialIn many cases of physical interest, the 6-function potential is a very convenient approximation to more structured, and more difficult, short-ranged potentials. In relativistic theories, its use is often mandated because only a mathematical point has a relativistically invariant shape. Neverthele...Delta function; Energy states1981-09
151 - 175 of 1,952