UScholar Works
 
Filters: School Or College: "College of Science" Collection: "ir_uspace" Type: "Text" Format: "application/pdf"
226 - 250 of 1,922
Number of results to display per page
CreatorTitleDescriptionSubjectDate
226 Lupton, John MarkStimulated emission depletion of triplet excitons in a phosphorescent organic laserTriplet formation is investigated in an optically pumped polymer laser by detecting the phosphorescence emission after excitation. A clear correlation is observed between the onset of lasing and a saturation of phosphorescence intensity due to stimulated emission depletion of the singlet state and t...Triplet excitons; Triplet formation; Emission depletion; Phosphorescent organic laser; Optically pumped polymer laser2006
227 Kieda, David B.; Gaisser, Thomas K.; Sokolsky, PierreCosmic-ray composition around 10^18 eVWe use the depth of maximum distribution as measured by the stereo Fly's Eye detector to study the chemical composition of the primary cosmic radiation between 3x 1017 eV and 1019 eV. The analysis depends on the use of simulations to study the response of the detector as well as sensitivity to assum...Fly's Eye; Cosmic ray composition; Cosmic ray nuclei; Chemical composition1993-03
228 DeTar, CarletonfB quenched and unquenchedResults for fβ, / fβs, /fD, /fDs , and their ratios are presented. High statistics quenched runs at β = 5.7, 5.85, 6.0, and 6.3, plus a run still in progress at β = 6.52 make possible a preliminary extrapolation to the continuum. The data allows good control of all systematic errors except for q...Decay constants; Wilson quarks1996-03
229 Coley, Phyllis D.What's up? Perspectives from the first international forest canopy conference at Sarasota, Florida, 1994Jumars, caribineers, pole pruners, tree bicycles, Bosun's chairs, booms, peconhas . . . these terms are not listed in most biological dictionaries. Nor are construction cranes or large treehouses or hot-air dirigibles listed as priority equipment for any scientific laboratories. But these are th...1995
230 Lupton, John MarkUltrafast dynamics of charge carrier photogeneration and geminate recombination in conjugated polymer: fullerene solar cellsWe investigate the nature of ultrafast exciton dissociation and carrier generation in acceptor-doped conjugated polymers. Using a combination of two-pulse femtosecond spectroscopy with photocurrent detection, we compare the exciton dissociation and geminate charge recombination dynamics in blends ...Ultrafast dynamics; Charge carrier photogeneration; Geminate recombination; Exciton dissociation; Acceptor-doped; MeLPPP; MDMO-PPV2005-11
231 Miller, Joel Steven; Epstein, Arthur J.Ferrimagnetic resonance in films of vanadium [tetracyanoethanide]x, grown by chemical vapor depositionFerrimagnetic resonance (FMR) measurements in thin films of V[TCNE]x grown by chemical vapor deposition exhibit a series of sharp lines at 300 K. The orientational dependence of these lines is a result of the sample geometry provided the magnetization tracks the applied magnetic field. The FMR inten...Spin; Anisotropy; Magnetization2004
232 Symko, Orest GeorgeAbsorption at radio frequencies in superconducting Y1Ba2Cu3OyThe large magnetic-field-dependent ac absorption in superconducting Y1Ba2Cu3Oy ceramics and powders decreases slowly with increasing frequency in the range 2-16 MHz. The magnetic-field-dependent ac absorption is observed below Tc in superconducting Y1Ba2Cu3Oy ceramics, powders and twinned crystals ...Copper-octahedral oxygen perovskites; Superconducting Y1Ba 2Cu3Oy; ac absorption1989
233 Vardeny, Zeev ValentineElectromodulated photoinduced absorption; a new spectroscopy in ∏-conjugated polymer/C60-blendsWe have applied the electromodulated photoinduced absorption (EPA) technique to a variety of C 6 0 -doped and pristine luminescent conducting polymer films. EPA measures the electric field-related change of the absorption in the sample as a result of above-gap illumination. An electric field leads t...Electromodulated photoinduced absorption; EPA; C60 doping; Electromodulated photoluminescence; EPL; Polaron pair polarizability1997
234 Gondolo, PaoloDetectability of weakly interacting massive particles in the Sagittarius dwarf tidal streamTidal streams of the Sagittarius dwarf spheroidal galaxy (Sgr) may be showering dark matter onto the solar system and contributing ~(0:3-23)% of the local density of our galactic halo. If the Sagittarius galaxy contains dark matter in the form of weakly interacting massive particles (WIMPs), the ext...WIMP; Weakly interacting massive particles; Sagittarius dwarf galaxy; Recoil energy; Sgr stream2005-02
235 Miller, Joel Steven; Epstein, Arthur J.Spin dilution in a ferromagnetic chainWe have systematically introduced spinless defects in the quasi-one-dimensional ferromagnetic system decamethylferrocenium tetracyanoethanide, [FeCp(2*)] [TCNE]. The three-dimensional ordering temperature Tc decreases rapidly with the concentration of spinless sites. The rate of decrease of Tc with...Magnetic; Magnetization; Spinless1992
236 Vardeny, Zeev ValentinePhotophysics of pristine and C60-doped disubstituted polyacetyleneUsing a variety of steady-state spectroscopies we studied the long-lived photoexcitations and electronic excited states of poly disubstituted acetylene (PDPA-nBu), the backbone structure of which is a disubstituted trans-polyacetylene, as well as PDPA-nBu/C60 blends. The cw spectroscopies include a...Photophysics; Pristine disubstituted polyacetylene; C60-doped disubstituted polyacetylene; pi-conjugated polymers; Photoexcitations; Electronic excited states2002-08
237 Shapiro, Michael D.Genetic architecture of parallel armor plate reduction in threespine sticklebacksHow many genetic changes control the evolution of new traits in natural populations? Are the same genetic changes seen in cases of parallel evolution? Despite long-standing interest in these questions, they have been difficult to address, particularly in vertebrates. We have analyzed the genetic bas...Genetic changes; Plate number; Genetic mapping2004
238 Hultine, Kevin; Sperry, John S.Transpiration and hydraulic strategies in a piñon-juniper woodlandAnthropogenic climate change is likely to alter the patterns of moisture availability globally. The consequences of these changes on species distributions and ecosystem function are largely unknown, but possibly predictable based on key ecophysiological differences among currently coexisting species...Drought; Hydraulic transport model; Juniperus osteosperma; Plant water use; Sap flux; Species distributions2008
239 DeTar, CarletonConjecture concerning the modes of excitation of the quark-gluon plasmaIt is a widely held belief that at temperatures much higher than the confinement scale of quantumchromodynamics (QCD), quarks and gluons become free, giving rise to a new form of matter, called the quark-gluon plasma. It is conjectured here that the characterization of the plasma as a free or weakl...Polyakov loops; Excitation1985-07
240 Clayton, Dale H.Neotropical tineidae, II: biological notes and descriptions of two new moths phoretic on spiny pocket mice in Costa Rica (Lepidoptera: Tineoidea)Two new species of tineid moths discovered riding on the backs of two species of spiny pocket mice (Heteromyidae) in Costa Rica are described. Amydria selvae, new species, was found on Heteromys desmarestianus Gray in the rainforest at Finca La Selva and Ptilopsaltis santarosae, new species, occurr...Neotropical Tineidae; Phoretic moths; Amydria selvae; Heteromys desmarestianus; Ptilopsaltis santarosae; Liomys salvini; Mouse moths1986
241 Vardeny, Zeev ValentinePhotocarrier dynamics in compensated hydrogenated amorphous siliconThe photocarrier dynamics in compensated a-Si:H is studied using the time-dependent photomodulation technique in the subpicosecond-to-millisecond time range. We find that photocarriers are quickly trapped in shallow impurity levels for t < 10 psec, similar to the behavior in singly doped materials...Photocarriers; a-Si:H; Amorphous silicon; Fast trapping1986-03
242 Clayton, Dale H.Two new species of Dennyus (Collodennyus) chewing lice (Phthiraptera: Amblycera: Menoponidae) from swiftlets (Apodiformes: Apodidae)The new species Dennyus (Collodennyus) mimirogerorum from the Papuan swiftlet, Aerodramus papuensis (Rand), from Papua New Guinea and D. (C.) bartoni from the Philippine swiftlet, A. mearnsi (Oberholser), from the Philippines are described and illustrated. The genetic distinctiveness of these two sp...Collodennyus; Chewing louse; Chewing lice; Swiftlets; Phthiraptera; Papuan swiftlet; Aerodramus papuensis2006
243 Vardeny, Zeev ValentineAmplified spontaneous emission and lasing in conducting polymers and fluorescent dyes in opals as photonic crystalsSpectral narrowing of photoluminescence (PL) and evolution of sharp emission lines upon optical excitation have been observed in opals made of SiO2 spheres infiltrated with conducting polymers such as OOPPV and MDDOPPV and also fluorescent dyes such as rhodamine 6G, NK-3483, and coumarin 120. Their ...Amplified spontaneous emission; Lasing; Fluorescent dyes1999
244 Wu, Yong-ShiTwo-loop analysis of non-Abelian Chern-Simons theoryPerturbative renormalization of a non-Abelian Chern-Simons gauge theory is examined. It is demonstrated by explicit calculation that, in the pure Chern-Simons theory, the & function for the coefficient of the Chern-Simons term vanishes to three-loop order. Both dimensional regularization and regula...Chern-Simons theory; Yang-Mills theory; Regularization1992-12
245 Ailion, David Charles14N study of the role of N-D---O bonds in the deuteron glass transition14N spin-lattice relaxation-time measurements in Rb0.28(ND4)0.72D2PO4 provide direct evidence for the fast exchange averaging of the "long" and "short" N-D---O hydrogen bonds between the ND4 group and the four surrounding PO4 groups. This exchange and the associated distortion of the ND4 tetrahedron...NMR; Hydrogen bonds; Spin-lattice; Relaxation-time; Deuteron glass1999
246 Vardeny, Zeev ValentineStudies of polymer microring lasers subject to uniaxial stressThe emission spectra of microring lasers fabricated from ∏-conjugated polymer films casted on nylon microfibers with diameters in the range of 35-90 µm were studied upon application of uniaxial stress with strain up to ~12%. The laser emission spectra substantially change with the applied stress,...pi-conjugated polymers; Microring lasers; Uniaxial stress; DOO-PPV2007
247 Olivera, Baldomero M.; Ireland, Chris M.NMR structures of conotoxinsThis review discusses the methodology, structural details, and biological implications regarding NMR structures of conotoxins. NMR and molecular modeling techniques have improved to the point that three-dimensional structures of conotoxins can now be determined with a significant degree of confiden...Conotoxins1996
248 Williams, Clayton C.Two step dopant diffusion study performed in two dimensions by scanning capacitance microscopy and TSUPREM IVWe report the results of a two-step two- dimensional (2D) diffusion study by scanning capacitance microscopy (SCM) and 2D SUPREM IV process simulation. A quantitative 2D dopant profile of a gate-like structure is measured with the SCM on a cross-sectioned polished silicon wafer. The gate-like struct...Scanning capacitance microscopy; SCM; Doping1998
249 Morse, Michael DavidRotationally resolved spectra of Pt?High-resolution laser-induced fluorescence spectroscopy has been used to investigate the 18 163 cm21 band of Pt2 in a supersonically cooled molecular beam. Rotational constants of the ground and excited states were extracted from the rotationally resolved spectrum and determined to be B0'=0.031 754(...2002
250 Wu, Yong-ShiOne-loop shift in noncommutative Chern-Simons couplingIn this paper we study the one-loop shift in the coupling constant in a noncommutative pure U(N) Chern-Simons gauge theory in three dimensions. The one-loop shift is shown to be a constant proportional to N, independent of noncommutativity parameters, and non-vanishing for U(1) theory. Possible phy...2001-01
226 - 250 of 1,922