Physical Sciences and Mathematics Commons^™

Bounded Point Evaluations And Local Spectral Theory, Abdellatif Bourhim

Mathematics - All Scholarship

We study in this paper the concept of bounded point evaluations for cyclic operators. We give a negative answer to a question of L.R. Williams Dynamic Systems and Apllications 3(1994) 103-112. Furthermore, we generalize some results of Williams and give a simple proof of theorem 2.5 of L.R. Williams (The Local Spectra of Pure Quasinormal Operators J. Math. anal. Appl. 187(1994) 842-850) that non normal hyponormal weighted shifts have fat local spectra.

Oxidation Of [(Cyclic Triamine)(1,5-Cyclooctadiene)Iridium]+ Cations By Hydrogen Peroxide Forms Metallaoxetanes, Thomas C. Flood, Masanori Iimura, Jeremy M. Perotti, Arnold L. Rheingold, Thomas E. Concolino

Chemistry and Physics Faculty Articles

Iridaoxetane 3 formed by oxidation of 1 with aqueous H₂O₂ is isolated and characterized, providing a rare example of formation of a metallaoxetane by direct oxidation of a metal–alkene complex.

Exploring The Structure Of A Possible Light Scalar Nonet, Joseph Schechter, Deirdre Black, Amir H. Fariborz

Physics - All Scholarship

We first review the work of the Syracuse group, which uses an effective chiral Lagrangian approach, on meson-meson scattering. An illustration providing evidence for the existence of a strange scalar resonance of mass around 900 MeV is given. An attempt to fit this \kappa (900) together with a similarly obtained \sigma (560) and the well known a_0(980) and f_0(980) into a nonet pattern suggests that the underlying structure is closer to a dual quark-dual antiquark than to a quark-antiquark. A possible mechanism to explain a next higher-in mass scalar meson nonet is also discussed. This involves mixing between q{\bar q} …

Total Cross Sections For Dissociative Electron Attachment In Dichloroalkanes And Selected Polychloroalkanes: The Correlation With Vertical Attachment Energies, Kayvan Aflatooni, Paul Burrow

Paul Burrow Publications

Electron attachment into the lowest unoccupied molecular orbital of a typical polychloroalkane in the gas phase forms a temporary negative ion in which the impinging electron resides on a combination of local C–Cl σ* orbitals. Because of the antibonding character of these orbitals, these anions may dissociate, producing Cl^- with cross sections that vary enormously over the chloroalkane family. In this work, we present absolute total dissociative electron attachment (DEA) cross sections for 33 of these compounds, and we show that the peak values of the cross sections correlate strongly with the vertical attachment energies (VAEs) for formation of …

Low-Mass Spectroscopic Binaries In The Hyades: A Candidate Brown Dwarf Companion, I. Neill Reid, S. Mahoney

Dartmouth Scholarship

We have used the HIRES echelle spectrograph on the Keck I telescope to obtain high-resolution spectroscopy of 51 late-type M dwarfs in the Hyades cluster. Cross-correlating the calibrated data against spectra of white dwarfs allows us to determine heliocentric velocities with an accuracy of ±0.3 km s⁻¹. 27 stars were observed at two epochs in 1997; two stars, RHy 42 and RHy 403, are confirmed spectroscopic binaries. RHy 42 is a double-lined, equal-mass system; RHy 403 is a single-lined, short-period binary, P∼1.275 d. RHy 403A has an absolute magnitude of M_I=10.85, consistent with a mass …

Search For R-Parity Violation In Multilepton Final States In Pp̅ Collisions At √S = 1.8 Tev, B. Abbott, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

The result of a search for gaugino pair production with a trilepton signature is reinterpreted in the framework of minimal supergravity (MSUGRA) with R-parity violation via leptonic λ Yukawa couplings. The search used 95 pb^-1 of pp̅ collisions at √s =1.8 TeV recorded by the DO. detector at the Fermilab Tevatron. A large domain of the MSUGRA parameter space is excluded for λ₁₂₁, λ₁₂₂>10^-4.

Measurement Of Exclusive Ω Electroproduction At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

The exclusive electroproduction of ω mesons, ep → e ω p, has been studied in the kinematic range 3 < Q2 < 20 GeV2, 40 < W < 120 GeV and |t| < 0.6 GeV2 with the ZEUS detector at HERA using an integrated luminosity of 37.7 pb-1. The ω mesons were identified via the decay ω → π+ π- π0. The exclusive cross section in the above kinematic region is σ(ep) → e ω p = 0.108 ± 0.014 (stat.) ± 0.026(syst.) nb. The reaction ep → e φ p, φ → π+ π- π0, has also been measured. The cross sections, as well as the ratios σ γ·p → ωp/σ γ · p → p0p and σ γ · p → ωp/σγ·p → φp, are presented as a function of W and Q2. Thus, for the first time, the properties of ω electroproduction can be compared to those of p0,φ and J/ψ electroproduction at high W. (C) 2000 Elsevier Science B.V.

Nondestructive Single-Photon Trigger, John C. Howell, John A. Yeazell

Mathematics, Physics, and Computer Science Faculty Articles and Research

A triggering device sensitive to a single photon is discussed. It is based on a balanced quantum nondemolition (QND) measurement proposed by Chuang and Yamamoto [Phys. Rev. Lett. 76, 4281 (1996)]. The balanced measurement measures the total photon number and obtains no which-path/mode information. Hence, the timing of the photon can be determined without destroying its wave function or entangling the probe field. This could have extensive use in the realization of long-distance quantum communications systems.

Relationships Between Abundance Of Physically Complex Habitat And Benthic Macroinvertebrate Community Parameters In The James River, Nelson County, Va, Tammy Lee Shumaker

Theses & Honors Papers

This study shows the importance of structurally complex habitat on abundance and diversity of organisms in a benthic macroinvertebrate community in the James River, Nelson County, Virginia. Structural complexity was manipulated by attaching stones to five concrete blocks (12.8 ± 0.97% coverage; mean ± SE) and comparing organism abundance on these blocks and blocks lacking stones (0% coverage). Concrete blocks were randomly placed at a site in the James River on November 14, 1999 and collected on December 12, 1999. Macroinvertebrates and particulate organic and inorganic matter on the blocks were collected. Total invertebrate abundance, abundance of eight individual taxa, …

Clathrate Structure For Electronic And Electro-Optic Applications, Leonid Grigorian, Peter C. Eklund, Shaoli Fang

Physics and Astronomy Faculty Patents

A method including the steps of (a) depositing a metal layer on a selected portion of a silicon substrate under a first set of predetermined conditions to form an metal silicide layer and an intermediate n-type silicon layer; and (b) exposing the metal silicide layer and the n-type silicon layer to a second set of predetermined conditions to form a silicon clathrate film on the selected portion of the silicon substrate, where the intermediate n-type silicon layer acts to bond the silicon clathrate to the silicon substrate to form a silicon clathrate structure.

Biological Implications Of A Discrete Mathematical Model For Collagen Deposition And Alignment In Dermal Wound Repair, J. C. Dallon, J. A. Sherratt, P. K. Maini, M. W. Ferguson

Faculty Publications

We develop a novel mathematical model for collagen deposition and alignment during dermal wound healing. We focus on the interactions between fibroblasts, modelled as discrete entities, and a continuous extracellular matrix composed of collagen and a fibrin based blood clot. There are four basic interactions assumed in the model: fibroblasts orient the collagen matrix, fibroblasts produce and degrade collagen and fibrin and the matrix directs the fibroblasts and determines the speed of the cells. Several factors which influence the alignment of collagen are examined and related to current anti-scarring therapies using transforming growth factor " The most influential of these …

Phase Diagram Of Four-Dimensional Dynamical Triangulations With A Boundary, Simon Catterall, Simeon Warner

Physics - All Scholarship

We report on simulations of DT simplicial gravity for manifolds with the topology of the 4-disk. We find evidence for four phases in a two-dimensional parameter space. In two of these the boundary plays no dynamical role and the geometries are equivalent to those observed earlier for the sphere S^4. In another phase the boundary is maximal and the quantum geometry degenerates to a one dimensional branched polymer. In contrast we provide evidence that the fourth phase is effectively three-dimensional. We find discontinuous phase transitions at all the phase boundaries.

Transient Spin Structures At The Antifero-To-Paramagnetic Phase Boundary Of Febr2, Christian Binek

Christian Binek Publications

Excess magnetization and anomalous susceptibility loss is observed on antiferromagnetic FeBr2 in an axial field H below and above its H-T-phase boundary between the multicritical temperature (Tm = 4.6 K) and the Néel temperature (TN = 14.1 K). These and other unusual properties of FeBr2 are attributed to frustration-induced intraplanar non-critical spin fluctuations, which can be simulated within the framework of a triaxial version of the 2D-ANNNI model.

Optimal Token Allocations In Solitaire Knock'm Down, Arthur T. Benjamin, Mark L. Huber, Matthew T. Fluet '99

All HMC Faculty Publications and Research

In the game Knock 'm Down, tokens are placed in N bins. At each step of the game, a bin is chosen at random according to a fixed probability distribution. If a token remains in that bin, it is removed. When all the tokens have been removed, the player is done. In the solitaire version of this game, the goal is to minimize the expected number of moves needed to remove all the tokens. Here we present necessary conditions on the number of tokens needed for each bin in an optimal solution, leading to an asymptotic solution.

Crossover From Transient Spin Structures Ot The Field-Induced Griffiths Phase Of Febr2, Christian Binek

Christian Binek Publications

In the presence of an applied axial magnetic field Ha the uniaxial antiferromagnets FeCl2 and FeBr2 show fluctuating domain-like antiferromagnetic correlations above the phase boundary Tc(Ha). They are detected by SQUID measurements of the low frequency out-of-phase susceptibility gc″ and indicate a field-induced Griffiths phase at temperatures Tc(Ha) < T < TN. In contrast to FeCl2, important additional frustration-induced intraplanar non-critical contributions to χ″ vs. T are found in FeBr2. For external fields above the Tc(Ha) line, Ha > 2.6 MA/m, they are shown to superimpose linearly on the Griffiths contributions. These dominate at Ha = 2.67 MA/m and are unequivocally modeled within the Landau theory of fluctuations near phase transitions by introducing a Lorentzian Tc distribution.

Limits On Light Gravitino Production And New Processes With Large Missing Transverse Energy In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

Events collected by the Collider Detector at Fermilab (CDF) with an energetic jet plus large missing transverse energy can be used to search for physics beyond the standard model. We see no deviations from the expected backgrounds and set upper limits on the production of new processes. We consider in addition the production of light gravitinos and set a limit at 95% confidence level on the breaking scale √F ≥ 217 GeV, which excludes gravitino masses smaller than 1.1 x 10^-5 eV/c².

Bioindication Of Atmospheric Heavy Metal Deposition In The Blue Ridge Using The Moss Thuidium Delcatulum, Johathan Scott Schilling

Theses & Honors Papers

Heavy metals in the environment pose a risk to human health as well as to ecosystem health. These metals are released into the atmosphere as a result of industrial processes, and can be transported away from their sources to be deposited into the environment. Ectohydric mosses are known accumulators of atmospheric heavy metals, and their tissue can be used to quantify integrated deposition of these metals over time in the ecosystem.

In this study, the moss Thuidium delicatulum (Hedw.) was used to quantify lead (Pb), copper (Cu), chromium (Cr), and nickel (Ni) concentrations in the central Blue Ridge of Virginia …

Measurement Of The Proton Structure Function F2 At Very Low Q2 At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti, G. Levi

Faculty Publications

A measurement of the proton structure function F2(x, Q2) is presented in the kinematic range 0.045 GeV2 < Q2 < 0.65 GeV2 and 6 · 10-7 < x < 1 · 10-3. The results were obtained using a data sample corresponding to an integrated luminosity of 3.9pb-1 in e+ p reactions recorded with the ZEUS detector at HERA. Information from a silicon-strip tracking detector, installed in front of the small electromagnetic calorimeter used to measure the energy of the final-state positron at small scattering angles, together with an enhanced simulation of the hadronic final state, has permitted the extension of the kinematic range beyond that of previous measurements. The uncertainties in F2 are typically less than 4%. At the low Q2 values of the present measurement, the rise of F2 at low x is slower than observed in HERA data at higher Q2 and can be described by Regge theory with a constant logarithmic slope δlnF2/δln(1/x). The dependence of F2 on Q2 is stronger than at higher Q2 values, approaching, at the lowest Q2 values of this measurement, a region where F2 becomes nearly proportional to Q2. (C) 2000 Elsevier Science B.V.

Deer Management At Airports: A Case Study, J. Harris Glass

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Deer living on and around airports pose a threat to aircraft. The consequence of a deer-aircraft strike can be serious and potentially tragic. Nationally, cervids (deer) accounted for 67% of all reported mammal-aircraft strikes and have caused damage in 81% of deer strikes in the United States (Cleary et al. 1999). Due to the potential for damage, the Federal Aviation Administration and USDA-APHIS-Wildlife Services (WS) program recommend a zero-tolerance of deer on an airfield. Deer densities at Newport News / Williamsburg International Airport (PHF) were as high as 171.5 deer/mi² at the onset of the Wildlife Hazard Assessment conducted …

Utility Of Tdwr And Asr-9 Data To Mitigate Bird Strikes At Commercial Airports, Mark A. Isaminger, Mark E. Weber

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Conflicts between birds and commercial aircraft are a noteworthy problem at both large and small airports. The risk factor for U.S. airports continues to increase due to the steady rise in take-off/landings and bird populations. The focus of bird strike mitigation in the past has centered primarily on Wildlife Management techniques. Recently, an Avian Hazard Advisory System (AHAS) has been developed to reduce the risks of bird strikes to military operations. This system uses a mosaic of data collected by the Next Generation Weather Radar (NEXRAD). This sensor serves as an excellent tool for enroute bird advisories due to the …

Summary Of Bird Ingestions Into Aircraft Engines: Current Industry Activity And Bird Strike Reporting, Richard Parker

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

This presentation will show some of the bird strikes and/or trends to engines in the past few years. The presentation will emphasize the safety aspects associated with aircraft engine bird ingestions and show the current statistics as understood by the engine manufacturers. The presentation will also address industry activity related to the hazard of larger birds. There will also be comments relative to the importance of accurate and complete bird strike reporting now that many agencies are reporting and collecting data.

An Evaluation Of Techniques For The Control Of Birds On Landfills Near Airports, John Allan, Andy Baxter

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

This paper reports progress on an investigation of a variety of bird deterrent techniques on landfill sites. The objective of the study is to develop and test integrated bird management strategies for use on landfills, both close to airports and elsewhere. The first phase of the study is designed to evaluate individual techniques such as distress calls, pyrotechnics, falcons etc. to determine efficacy, time to habituation and differences in effectiveness for different pest bird species. Once the most promising techniques are identified they will be combined into integrated programs and tested long term on a various landfill sites across the …

Analysis Of The Use Of Radio-Controlled Models In Bird Dispersal, Nicholas B. Carter

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Border Collie Rescue (BCR), in cooperation with the Dover Air Force Base, conducted a series of field trials to test the efficacy of utilizing radio-controlled models (“RCs”) (aircraft and boats) in dispersing several species of birds from troublesome locations around the Dover AFB environment. Results of these trials suggest that RCs can be used to effectively harass seagulls, raptors, ducks, and geese from difficult areas, though there are a number of limitations that must be taken into account when determining the value of instituting a harassment program utilizing RCs. Though use of Border Collies in its wildlife management program had …

Wildlife Control At Vancouver International Airport: Introducing Border Collies, Dave Ball

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Situated on an island located along a major Pacific Flyway, Vancouver International Airport (YVR) has developed a comprehensive wildlife management program in order to maintain a safe aircraft operating environment. YVR attracts a diverse range of bird species, including: ducks; gulls; herons; geese (Canada and Snow); sparrows; swallows; crows; starlings; owls; hawks; and eagles. The airport’s Wildlife Management Program consists of a Habitat Management Program and a Wildlife Control Program which are both based on a database of knowledge the airport continues to build regarding the behaviour patterns of wildlife common to the airport. Operating 24-hours-per-day 365 days of the …

Creating A Wildlife Program, Dan Wood

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

In Feb 2000 Dover AFB hired a wildlife contractor utilizing a Border Collie as one of the main tools in our BASH program. The introduction of the Border Collie, as a tool in bird abatement was thoroughly researched. Since no other base had any other program like this an initial statement of work had to be written. A climate study was conducted with base personnel, the base veterinarian, legal office and the state department of natural resources on the idea of using a dog to harass wildlife. The major obstacles in creating a program this diverse and using a civilian …

A Better Way To Record And Report On Wildlife Movements, Greg Winfield

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

As a former Controller, I’ve recognized that Wildlife Officers usually end up producing hand-counted reports that often fail to highlight critical data such as species trends, primary attractants, dispersant ratios, migration timings, etc. I have written a software program that specifically addresses this problem. AIRMAN (Animal Interdiction Report Manager) is a complete stand-alone program that reports on all aspects of wildlife intervention. There are no calculations to be made, nor any wading through a myriad of daily logs for answers. CYYZ have seen the advantage and have implemented this software already. It produces Line Graphics to display trends based on …

Management Of Silver Gulls To Prevent Bird Strikes At Sydney Airport, Aimee Hutchinson

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

A bird strike is defined as a collision between a bird and an aircraft. While most bird strikes cause little or no damage to the aircraft, some incidents can be fatal and at the least, very costly. The majority of bird strikes occur during landing or take-off thus the focus of bird management is centered around the airport environments. The geographical features surrounding Sydney Airport include a number of bird-attracting water bodies: Botany Bay, Botany Wetlands, the Cooks River and Alexandra Canal. These features attract a diverse and abundant assemblage of migratory and coastal bird species including silver gulls ( …

The Avian Hazard Advisory System (Ahas): Operational Use Of Weather Radar For Reducing Bird Strike Risk In North America, T. Adam Kelly, Ron Merritt, Andreas Smith, Mark Howera, Ron White

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

The Avian Hazard Advisory System (AHAS) was developed to use NEXRAD weather radar data and National Weather Service (NWS) weather data to forecast and monitor bird activity. The system was tested in a pilot study in 1998 and became operational for the eastern 1/3 of the USA in March 2000. Two thousand low level routes, ranges, airspace and military airfields are evaluated every hour. The monitoring of birds in near real time uses algorithms developed by Geo-Marine, Inc to isolate biological targets from weather. Removing the weather returns permits subsequent processing to retrieve information on bird strike risk to be …

Factors Associated With Damaging Bird Strikes For United States Air Force Aircraft, Christine A. Tedrow, Patrick F. Scanlon, James A. Parkhurst, Steve L. Mcmullin

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Analysis of strike data is critical to determine the true economic costs of bird strikes, determine the magnitude of safety issues, and develop preventive measures. Analysis of USAF bird-strike data identified trends and indicated suggested relationships among factors contributing to damaging strikes. From FY 1988 through FY 1997, the annual mean was 2,668 bird strikes with peaks evident in fall and spring. Daylight and dusk were hazardous for bird strikes. More bird strikes occurred during airfield operations and when aircraft were operating at low altitudes (and when soaring birds were more numerous). Aircraft speed, phase of flight, taxonomic group, bird …

Dispersal Of Soaring Raptors Using Radio-Controlled Aircraft, Mark Loud

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

The purpose of the Radio Control flying program is to aid in the effort of bird harassment. Because no one method can be successful in deterring birds from inhabiting the runway area, several different measures must be taken to ensure we are doing all we can to keep them away. Radio-controlled planes, combined with other techniques, are a valuable tool in the ongoing efforts against birds on the airfield. Radio-controlled (RC) planes can scare birds where other techniques fall short. With a range of over one mile, the RC planes can cover most of the runway/infield area while being controlled …