Physical Sciences and Mathematics Commons^™

Fragmentation, Impervious Surfaces And Water Quality: Quantifying The Effects Of Density And Spatial Arrangement, Elizabeth Brabec, Paul Richards, Stacey Schulte

Elizabeth Brabec

Impervious surfaces have for many years been recognized as an indicator of the intensity of the urban environment and, with the advent of urban sprawl, they have become a key issue in habitat health. In addition to the direct impacts to water quality, impervious surfaces fragment open space and habitat and are therefore a primary land use indicator of both water quality and ecological degradation. This paper develops an understanding of the land use planning implications of the interaction of impervious surfaces, water quality and the spatial form those surfaces take in a watershed. In order to clarify these relationships, …

Search For Scalar Top And Scalar Bottom Quarks In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have searched for direct pair production of scalar top and scalar bottom quarks in 88 pb^-1 of pp̅ collisions at √s =1.8 TeV with the CDF detector. We looked for events with a pair of heavy flavor jets and missing energy, consistent with scalar top (bottom) quark decays to a charm (bottom) quark and a neutralino. The numbers of events that pass our selections show no significant deviation from standard model expectations. We compare our results to the next-to-leading order scalar quark production cross sections to exclude regions in scalar quark-neutralino mass parameter space.

Weak-Singlet Fermions: Models And Constraints, Marko Popovic, Elizabeth Simmons

Marko B. Popovic

We employ data from precision electroweak tests and collider searches to derive constraints on the possibility that weak-singlet fermions mix with the ordinary standard model fermions. Our findings are presented within the context of a theory with weak-singlet partners for all ordinary fermions and theories in which only third-generation fermions mix with weak singlets. In addition, we indicate how our results can be applied more widely in theories containing exotic fermions.

Ip Forwarding Alternatives In Cell Switched Optical Networks, P. Boustead, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

Optical switching will enable core Internet packet switching to scale with future transmission rate increases. Currently proposed optical ATM switches do not allow packet reassembly, which is necessary for packet level forwarding. This results in the requirement to create end to end ATM virtual connections for flows even if they contain only one packet. In electronically switched networks MPOA and MPLS allow both cell and packet level forwarding to overcome this problem. This paper examines the feasibility of implementing such protocols over an optically switched network. Two different architectures are examined: use of an adjunct electrical router; and native optical …

Unfairness And Capture Behaviour In 802.11 Adhoc Networks, C. Ware, J. Judge, Joe F. Chicharo, E. Dutkiewicz

Faculty of Informatics - Papers (Archive)

We address issues with the performance of IEEE 802.11, when used in the adhoc mode, in the presence of hidden terminals. We present results illustrating the strong dependence of channel capture behavior on the SNR observed on contending hidden connections. Experimental work has illustrated that in a hidden terminal scenario, the connection having the strongest SNR is able to capture the channel, despite the use of the RTS-CTS-DATA-ACK 4-way handshake designed to alleviate this problem. Our results indicate that the near-far SNR problem may have a significant effect on the performance of an adhoc 802.11 network.

The Complexity Of Planning With Partially-Observable Markov Decision Processes, Martin Mundhenk

Computer Science Technical Reports

This work surveys results on the complexity of planning under uncertainty. The planning model considered is the partially-observable Markov decision process. The general planning problems are, given such a process, (a) to calculate its performance under a given control policy, (b) to find an optimal or approximate optimal control policy, and (c) to decide whether a good policy exists. The complexity of this and related problems depend on a variety of factors, including the observability of the process state, the compactness of the process representation, the type of policy, or even the number of actions relative to the number of …

Electronic Structure Of Bas And Boride Iii-V Alloys, Gus L. W. Hart, Alex Zunger

Faculty Publications

Boron arsenide, the typically ignored member of the Group-III–V arsenide series BAs-AlAs-GaAs-InAs is found to resemble silicon electronically: its Γ conduction-band minimum is p-like (Γ15), not s-like (Γ1c), it has an X1c-like indirect band gap, and its bond charge is distributed almost equally on the two atoms in the unit cell, exhibiting nearly perfect covalency. The reasons for these are tracked down to the anomalously low atomic p orbital energy in the boron and to the unusually strong s–s repulsion in BAs relative to most other Group-III–V compounds. We find unexpected valence-band offsets of BAs with respect to GaAs and …

Grb 991216 Joins The Jet Set: Discovery And Monitoring Of Its Optical Afterglow, J. P. Halpern, R. Uglesich, N. Mirabal, S. Kassin, J. Thorstenson, W. C. Keel, A. Diercks, J. S. Bloom, F. Harrison, J. Mattox, M. Eracleous

Dartmouth Scholarship

The optical light curve of the energetic γ-ray burst GRB 991216 is consistent with jetlike behavior in which a power-law decay steepens from t^-1.22+-0.04 at early times to t^{-1.53 +- 0.05} in a gradual transition at around 2 days. The derivation of the late-time decay slope takes into account the constant contribution of a host or intervening galaxy, which was measured 110 days after the event at R = 24.56 +- 0.14, although the light curve deviates from a single power law whether or not a constant term is included. The early-time spectral energy distribution of the afterglow …

Ria: Selecting Information To Include In Cooperative Task — Oriented Dialogues, Elise H. Turner

University of Maine Office of Research Administration: Grant Reports

The goal of this project was to delevop a technique for selecting information to volunteer in problem solving dialogues. The technique was to create usefulness ratings for information based on the problem solving of the agent that may communicate the information. Heuristics translate specific problem solving activities into contributions to the overall usefulness rating for the information. To this end, our objectives included determining the type of information that should be included in dialogues and implementing heuristics.

State-Selective Cross Section Scalings For Electron Capture Collisions, K. R. Cornelius, K. Wojtkowski, Ronald E. Olson

Physics Faculty Research & Creative Works

The classical-trajectory Monte Carlo method is used to calculate total and final nf state-selective electron capture cross sections for various fully stripped ions, ranging from He²⁺ to Ne¹⁰⁺, incident on H(ni = 1-4) and Li(2_s and 2_p) targets over the collision energies of 1-100 keV u^-1. Theoretical derivations of two scaling laws for state-selective electron capture cross sections as a function of collision energy, initial and final bound electron states and projectile charge are presented. The new scaling rules reduce the state-selective capture cross sections to very distinct universal curves. Curve fits …

Single Ionization Of Ne By Intense Laser Fields, C. R. Feeler, Ronald E. Olson

Physics Faculty Research & Creative Works

A three-dimensional classical Monte Carlo method has been used to examine the final state electron dynamics after single ionization of neon in an electric field generated by a short-pulse high-intensity laser. Linearly and circularly polarized fields were studied. Intensities ranging from 3 x 1014 to 3 x 1015 W cm^-2 were used with a wavelength of 800 nm and a full-width at half-maximum of 30 fs. At these values, the Keldysh parameter is less than one, making the classical approximation valid. A potential determined by Hartree-Fock calculations has been used to model the Ne atom. A kinematically complete picture …

Peak Flow Responses To Forest Practices In The Western Cascades Of Oregon, Usa, R. L. Beschta, M. R. Pyles, A. E. Skaugset, C. G. Surfleet

Natural Resources Management and Environmental Sciences

The effects of clearcut silviculture (road building, clearfelling, cable logging, and site preparation) were evaluated using long-term peakflow records for three small watersheds (60–101 ha) and six large basins (62–640 km²) in the western Cascades of Oregon, USA. After a calibration period, two of the small watersheds were treated while the third remained untreated (control). Analysis indicated that peakflow increases following treatments were dependent upon peakflow magnitude. Peakflow increases averaged approximately 13–16% after treatment for 1-yr recurrence interval events, and 6–9% for 5-yr recurrence interval events. For the six large basins, multiple linear regression analyses of peakflows relative …

Observation Of Phase-Matched Relativistic Harmonic Generation, Shouyuan Chen, Anatoly Maksimchuk, Eric Esarey, Donald P. Umstadter

Donald Umstadter Publications

Phase-matched relativistic harmonic generation in plasmas is observed for the first time. Third-harmonic light is detected and discriminated spectrally and angularly from the harmonics generated from competing processes. Its angular pattern is a narrow forward-directed cone, which is consistent with phase matching of a high-order transverse mode in a plasma. The signal level is found to be on the same order of magnitude for a circularly polarized pump pulse as for a linearly polarized pump pulse.

Final Technical Report For Grant De-Fg01-96ew56093 Nevada Risk Assessment/Management Program (Nramp), Donald H. Baepler, Anthony Hechanova

Nevada Risk Assessment/Management Program

The Nevada Risk Assessment/Management Program (NRAMP) was part of a national effort by the U.S. Department of Energy (DOE) to develop new sources of information and approaches to risk assessment, risk management, risk communication and public outreach as these objectives relate to the ecological and human health effects of radioactive and hazardous material management and site remediation activities. This final report presents a synopsis of the NRAMP effort that occurred from 1995 to 2000. Included in this report is a brief history of NRAMP including a description of the DOE Notice of Program Interest (NOPI) goals and how the NRAMP …

Chronic And Emerging Water Issues In The South Platte/Front Range Corridor, James S. Lochhead

Water and Growth in the West (Summer Conference, June 7-9)

16 pages.

Conjunctive Use In The Denver Basin: The Three Way Agreement, Peter D. Binney

Water and Growth in the West (Summer Conference, June 7-9)

14 pages.

Contains references.

Environmental Impacts Of New Solutions: Two Case Studies, Lori Potter, Michael Freeman

Water and Growth in the West (Summer Conference, June 7-9)

32 pages.

Contains footnotes and references.

Dimethylsulfoxide Reductase: An Enzyme Capable Of Catalysis With Either Molybdenum Or Tungsten At The Active Site, Lisa J. Stewart, Susan Bailey, Brian Bennett, John M. Charnock, C. David Garner, Alan S. Mcalpine

Physics Faculty Research and Publications

DMSO reductase (DMSOR) from Rhodobacter capsulatus, well-characterised as a molybdoenzyme, will bind tungsten. Protein crystallography has shown that tungsten in W-DMSOR is ligated by the dithiolene group of the two pyranopterins, the oxygen atom of Ser147 plus another oxygen atom, and is located in a very similar site to that of molybdenum in Mo-DMSOR. These conclusions are consistent with W L_III-edge X-ray absorption, EPR and UV/visible spectroscopic data. W-DMSOR is significantly more active than Mo-DMSOR in catalysing the reduction of DMSO but, in contrast to the latter, shows no significant ability to catalyse the oxidation of DMS.

Personal Radio, John C. Artz Jr

Dartmouth College Undergraduate Theses

With the development of new technologies that allow the broadcast of digital data over radio signals, there are many possibilities for improving upon the traditional radio station model for content delivery. The idea of Personal Radio is a system that tailors content to meet the needs of each individual. Using Global Positioning System (GPS) technology to play location specific content, the listening history to play content an appropriate number of times, and user feedback to learn personal preferences, the Personal Radio provides the listener with the content that is the most useful/interesting to them. This paper will examine the general …

Growth In Colorado And The West: Trends And Issues [Outline], James N. Corbridge Jr.

Water and Growth in the West (Summer Conference, June 7-9)

4 pages.

Contains references.

Issues Associated With New Developments And Transfers: A West Slope Perspective, Eric Kuhn

Water and Growth in the West (Summer Conference, June 7-9)

8 pages.

Gunnison River: A Local Perspective On Union Park, John R. Hill, Jr.

Water and Growth in the West (Summer Conference, June 7-9)

11 pages.

Impacts Of Water Transfers On The Agricultural Sector, Don Ament

Water and Growth in the West (Summer Conference, June 7-9)

2 pages.

Contains one reference.

Activities Of The Eagle River Assembly, Douglas Kemper

Water and Growth in the West (Summer Conference, June 7-9)

14 pages (includes illustrations).

Potential For Coordinated Facilities Management Along The Northern Front Range, Marc Waage

Water and Growth in the West (Summer Conference, June 7-9)

2 pages.

Emerging Demands In The Colorado Headwaters, Taylor Hawes

Water and Growth in the West (Summer Conference, June 7-9)

8 pages.

Doing More With Less: Remaining Opportunities For “Tuning The System”: The Potential For Central Valley System-Wide Conjunctive Water Management, Gregory A. Thomas

Water and Growth in the West (Summer Conference, June 7-9)

30 pages (includes illustrations).

Contains footnotes.

Protecting Instream Flows In Prior Appropriation States: Legal And Policy Issues, Janet C. Neuman

Water and Growth in the West (Summer Conference, June 7-9)

17 pages.

Climate Variability And Western Water: What Can We Expect?, Roger S. Pulwarty

Water and Growth in the West (Summer Conference, June 7-9)

7 pages.

Entangling Macroscopic Quantum States, John C. Howell, John A. Yeazell

Mathematics, Physics, and Computer Science Faculty Articles and Research

Spatial entanglements of macroscopic quantum systems are proposed. The which-path uncertainty of a single photon passing through a beam splitter is transformed into the which-path uncertainty of two macroscopic fields via two quantum nondemolition measurements. The macroscopic fields are nonlocally correlated.