Physical Sciences and Mathematics Commons^™

Direct Search For Charged Higgs Bosons In Decays Of Top Quarks, V. M. Abazov, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We present a search for charged Higgs bosons in decays of pair-produced top quarks in pp̅ collisions at√s = 1.8 TeV recorded by the D0 detector at the Fermilab Tevatron collider. With no evidence for signal, we exclude most regions of the (M_H±, tan β) parameter space where the decay t → H⁺b has a branching fraction >0.36 and B(H^± → τν_τ is large.

Diffractive Dijet Production At √S= 630 And 1800 Gev At The Fermilab Tevatron, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report a measurement of the diffractive structure function F_jj^D of the antiproton obtained from a study of dijet events produced in association with a leading antiproton in p̅p collisions at √s =630 GeV at the Fermilab Tevatron. The ratio of F_jj^D at √s =630 GeV to F_jj^D obtained from a similar measurement at √s =1800 GeV is compared with expectations from QCD factorization and other theoretical predictions. We also report a measurement of the ξ(x-Pomeron) and β(x of parton in Pomeron) dependence of F_jj^D at √s =1800 GeV. In the region …

Coercive Fields In Ferroelectrics: A Case Study In Lithium Niobate And Lithium Tantalate`, Sungwon Kim, Venkatraman Gopalan, Alexei Gruverman

Alexei Gruverman Publications

The experimentally measured coercive electric fields for domain reversal in ferroelectrics are typically many orders of magnitude lower than the estimates from phenomenological free-energy theory. This letter specifically investigates the influence of polarization gradients at pre-existing 180° domain walls in ferroelectrics on coercive fields for domain wall motion. It is shown that the ratio of theoretical coercive field without and with a preexisting domain wall is directly proportional to the ratio x_o /a, where a is the lattice parameter and 2x_o is the polarization wall width. This factor is 7.5–45 for a 20–120 nm wall width, the latter …

Late-Quaternary Lowstands Of Lake Titicaca: Evidence From High-Resolution Seismic Data, Karin D'Agostino, Geoffrey Seltzer, Paul A. Baker, Sherilyn C. Fritz, Robert Dunbar

Department of Earth and Atmospheric Sciences: Faculty Publications

Approximately 600 km of high-resolution seismic reflection data were collected to investigate the late-Quaternary stratigraphic development of Lake Titicaca. The focus of this report is on two seismic sequence boundaries, which are interpreted as erosional surfaces formed at times of low lake level. The younger erosional surface occurs as much as 90 m below the present lake level and up to 8 m below the present sediment–water interface. This erosional surface is interpreted to be coeval with a well-documented early- to mid-Holocene lowstand, dated between ~8,000 and 3,600 cal yr BP. An earlier and previously unknown erosional surface occurs at …

De Haas-Van Alphen Oscillations In The Quasi-Two-Dimensional Organic Conductor Κ-(Et)2cu(Ncs)2: The Magnetic Breakdown Approach, V. M. Gvozdikov, Yuriy V. Pershin Dr, E. Steep, A. G. M. Jansen, P. Wyder

Faculty Publications

We present both experimental data and an analytic theory for the de Haas–van Alphen ~dHvA! effect in the two-dimensional organic single-crystal conductor k -(ET)2Cu(NCS)2. We show that the magnetization oscillation pattern and the fast Fourier transform (FFT) spectrum of our measurements are well described theoretically within the coherent magnetic breakdown (MB) model for a two-dimensional Fermi surface consisting of two open sheets and closed pockets connected by magnetic breakdown centers. The spectrum of Landau quantized energy levels changes substantially due to the MB. Landau bands develop whose bandwidth and relative distance between them oscillate in inverse magnetic field. These oscillations …

Radiation Transport Modeling Of Beam-Target Experiments For The Aaa Project: Quaterly Report, William Culbreth

Reactor Campaign (TRP)

The national development of technology to transmute nuclear waste depends upon the generation of high energy neutrons produced by proton spallation. Proton accelerators, such as LANSCE at the Los Alamos National Laboratory, are capable of producing 800 MeV protons. By bombarding a lead/bismuth target, each proton may generate 500 or more neutrons that can activate fission products or induce the fission of transuranic isotopes.

The Monte Carlo radiation transport code MCNPX developed at LANL is an important tool in the design of transmuter technology. It must be validated, however, for the neutron energy that will be employed. Experiments are being …

Nuclear Criticality Analyses Of Separations Processes For The Transmutation Fuel Cycle: Quarterly Report, William Culbreth, Pang Tao

Separations Campaign (TRP)

During the first two quarters of the work, the tasks included training students in the use of Monte Carlo codes used in radiation transport studies and the assessment of neutron multiplication factors for specific problems outlined by ANL-East through Drs. Laidler and Vandegrift.

The proposal also included objectives for the first year of work on this project, as listed below. The work conducted in the second quarter of the project was in partial completion of these objectives.

• Train UNLV students in the use of SCALE and/or MCNP for the assessment of nuclear criticality.

• Assess neutron multiplication factor, k …

Transport Properties Of Polycrystalline Type-I Sn Clathrates, G. S. Nolas, J. L. Cohn, Jeffrey Dyck, C. Uher, J. Lang

Jeffrey Dyck

Thermal conductivity, resistivity, Seebeck coefficient, and Hall measurements on polycrystalline Sn-clathrate compounds with the type-I hydrate crystal structure are reported. Interstitial alkali-metal atoms in these compounds reside inside polyhedral cavities formed by the tetrahedrally bonded Sn network atoms. Localized disorder associated with “rattling” motion of these interstitial atoms contributes to the low thermal conductivity of these semiconducting compounds. The Hall coefficient and resistivity for some compounds exhibit nonmonotonic temperature dependences consistent with a crossover with decreasing temperature from conduction-band to impurity-band conduction. The carrier mobility is found to be low even in the absence of interstitial atoms within the Sn …

Three-Body Dynamics In Hydrogen Ionization By Fast Highly Charged Particles, J. Fiol, Ronald E. Olson

Physics Faculty Research & Creative Works

Electron double and triple differential cross sections are calculated as a function of projectile momentum transfer for ionization of ground and excited state hydrogen by 3.6 MeV u^-1 C⁶⁺ and Au⁵³⁺ ions. These three-body Coulomb systems are investigated using the classical-trajectory Monte Carlo and continuum distorted wave methods that incorporate all interactions including the nuclear-nuclear potential. The calculations allow one to distinguish cross section features associated with three collision mechanisms. The first is due to distance collisions that lead primarily to a binary interaction between the projectile and electron. The second is a strong three-body interaction by …

Design And Analysis Of A Process For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Yitung Chen, Darrell Pepper, Randy Clarksean

Fuels Campaign (TRP)

UNLV has developed and will continue to develop process models for the analysis of melt casting processes. This work will continue to be performed under the guidance of Argonne National Laboratory (ANL) engineers to ensure that their knowledge and experience benefits the project. The research to be conducted during the second year will center on performing detailed analyses on a conceptual design of an inductively heated skull-crucible casting furnace. Processing conditions will be analyzed, basic models utilized, and detailed heat and mass transfer models will be developed to analyze the most promising processes. The goal of this second year is …

Footprinting And Circular Dichroism Studies On Paromomycin Binding To The Packaging Region Of Human Immunodeficiency Virus Type-1, Mark P. Mcpike, Jerry Goodisman, James C. Dabrowiak

Chemistry - All Scholarship

We have studied the interaction of the aminoglycoside drug, paromomycin, with a 171-mer from the packaging region of HIV-1 (ψ-RNA), using quantitative footprinting and circular dichroism spectroscopy. The footprinting autoradiographic data were obtained by cutting end-labeled RNA with RNase I or RNase T1 in the presence of varying paromomycin concentrations. Scanning the autoradiograms produced footprinting plots showing cleavage intensities for specific sites on the ψ-RNA as functions of drug concentration. Footprinting plots showing binding were analyzed using a two-state model to give apparent binding constants for specific sites of the ψ-RNA. These plots show that the highest-affinity paromomycin binding site …

A Three-Domain Structure For The Delta Subunit Of The Dna Polymerase Iii Holoenzyme Delta Domain Iii Binds Delta' And Assembles Into The Dnax Complex, James M. Bullard, Arthur E. Pritchard, Min Sun Song, Bradley P. Glover, Anna Wieczorek, Joe Chen, Nebojsa Janjic, Charles S. Mchenry

Chemistry Faculty Publications and Presentations

Using ψ-BLAST, we have developed a method for identifying the poorly conserved δ subunit of the DNA polymerase III holoenzyme from all sequenced bacteria. This approach, starting withEscherichia coli δ, leads not only to the identification of δ but also to the DnaX and δ′ subunits of the DnaX complex and other AAA⁺-class ATPases. This suggests that, although not an ATPase, δ is related structurally to the other subunits of the DnaX complex that loads the β sliding clamp processivity factor onto DNA. To test this prediction, we aligned δ sequences with those of δ′ and, using …

Improving The Campus Sustainability Assessment Process, Andrew Nixon

Honors Theses

The human enterprise is rapidly overwhelming the Earth’s ecological systems and draining its natural resources. According to Vitousek et al., as much as one-half of the planet’s land surface has been transformed by human activity; more than half of the world’s available fresh water is used by humans; and a quarter of the planet’s bird species have been driven to extinction by human activity (Vitousek et al, 1997). These and many other negative trends pose catastrophic implications for the future of our species and for the planet’s other inhabitants.

Method Of Solubilizing Unshortened Carbon Nanotubes In Organic Solutions, Robert C. Haddon, Jian Chen, Mark A. Hamon

Chemistry Faculty Patents

Naked carbon nanotubes are dissolved in organic solutions by terminating the nanotubes with carboxylic acid groups and attaching an aliphatic carbon chain so as to render the carbon nanotubes soluble.

Absolute Tin(111) Step Energies From Analysis Of Anisotropic Island Shape Fluctuations, S. Kodambaka, V. Petrova, S. V. Khare, Duane D. Johnson, I. Petrov, J. E. Greene

Duane D. Johnson

In situ high-temperature (1165–1248 K) scanning tunneling microscopy was used to measure fluctuations around the equilibrium shape of two-dimensional vacancy islands on TiN(111) terraces. From the equilibrium shape, the ratio of the two ⟨110⟩ step energies was found to be 0.72±0.02. Combining this with the results of an exact approach for analysis of shape fluctuations, applicable to highly anisotropic islands, we obtain absolute values for step energies and step stiffnesses as a function of orientation.

Post Stack Seismic Attribute Analysis, Zafer Özer, Turan Kayiran

Bulletin of the Mineral Research and Exploration

No abstract provided.

Sedimentology Of Oylat Cave Sedimentary Rocks İnegöl (Bursa), Eşref Atabey, Lütfi Nazi̇k, Koray Törk

Bulletin of the Mineral Research and Exploration

No abstract provided.

Geochemical Characteristics And Origin Of Barite Deposits Between Şarki̇karaağaç (Isparta) And Hüyük (Konya), Oya Cengi̇z, Mustafa Kuşcu

Bulletin of the Mineral Research and Exploration

No abstract provided.

Sea Stewards: A Volunteer Ecological Monitoring Program, Nicole D. Fogarty, Mary Enstrom

Marine & Environmental Sciences Faculty Reports

No abstract provided.

2002 - The Seventh Annual Symposium Of Student Scholars

Symposium of Student Scholars Program Books

The full program book from the Seventh Annual Symposium of Student Scholars, held on April 5, 2002. Includes abstracts from the presentations and posters.

The Formation Of Fissure Ridge Type Laminated Travertine-Tufa Deposits Microscopical Characteristics And Diagenesis, Kirşehi̇r Central Anatolia, Eşref Atabey

Bulletin of the Mineral Research and Exploration

No abstract provided.

Soft And Hard Interactions In Pp̅ Collisions At √S =1800 And 630 Gev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a study of pp̅ collisions at √s =1800 and 630 GeV collected using a minimum bias trigger by the CDF experiment in which the data set is divided into two classes corresponding to “soft” and “hard” interactions. For each subsample, the analysis includes measurements of the multiplicity, transverse momentum (p_T) spectrum, and the average p_T and event-by-event p_T dispersion as a function of multiplicity. A comparison of results shows distinct differences in the behavior of the two samples as a function of the center of mass (c.m.) energy. We find evidence that the …

Coalbed Methane In The San Juan Basin Of Colorado And New Mexico, Catherine Cullicott, Carolyn Dunmire, Jerry Brown, Chris Calwell

Coalbed Methane Development in the Intermountain West (April 4-5)

35 pages (includes color illustrations and maps).

Contains 6 pages of endnotes.

Coalbed Methane Development In Wyoming’S Powder River Basin, Diana Hulme

Coalbed Methane Development in the Intermountain West (April 4-5)

21 pages (includes color illustrations and maps).

Contains endnotes.

Powder River Basin Coalbed Methane Financial Model (Prb-Cbm-Fm), W. Thomas Goerold

Coalbed Methane Development in the Intermountain West (April 4-5)

12 pages (includes illustrations).

Contains references.

Overview Of Cbm Issues In The San Juan Basin, Catherine Cullicott

Coalbed Methane Development in the Intermountain West (April 4-5)

3 pages (includes some color illustrations and maps).

Impacts Of Cbm Development On Communities, Gwen Lachelt

Coalbed Methane Development in the Intermountain West (April 4-5)

2 pages.

Overview Of Cbm Issues In The Powder River Basin, Diana Hulme

Coalbed Methane Development in the Intermountain West (April 4-5)

3 pages (includes color map).

Air Quality And Cbm Development, Bob Yuhnke

Coalbed Methane Development in the Intermountain West (April 4-5)

5 pages (includes 1 color map).

Concluding Comments, Ayn Schmit

Coalbed Methane Development in the Intermountain West (April 4-5)

2 pages.