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2003

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Articles 391 - 420 of 3876

Full-Text Articles in Physical Sciences and Mathematics

Task Allocation Via Multi-Agent Coalition Formation: Taxonomy, Algorithms And Complexity, Hoong Chuin Lau, L. Zhang Nov 2003

Task Allocation Via Multi-Agent Coalition Formation: Taxonomy, Algorithms And Complexity, Hoong Chuin Lau, L. Zhang

Research Collection School Of Computing and Information Systems

Coalition formation has become a key topic in multiagent research. In this paper, we propose a preliminary classification for the coalition formation problem based on three driving factors (demands, resources and profit objectives). We divide our analysis into 5 cases. For each case, we present algorithms and complexity results. We anticipate that with future research, this classification can be extended in similar fashion to the comprehensive classification for the job scheduling problem.


Content-Aware Authentication Of Motion Jpeg2000 Stream In Lossy Networks, Yongdong Wu, Robert H. Deng Nov 2003

Content-Aware Authentication Of Motion Jpeg2000 Stream In Lossy Networks, Yongdong Wu, Robert H. Deng

Research Collection School Of Computing and Information Systems

Stream authentication schemes (SAS) aim to achieve effective authentication of multicast streams over lossy networks. Almost all the existing SASs is designed for stream data integrity protection only. In this paper, we argue that content integrity protection is more important than data integrity to human users. We present a content-aware SAS in motion JPEG2000 streaming. In our scheme, a chunk of JPEG2000 codestreams is encapsulated into a block of packets using multiple description coding (MDC). Our MDC exploits the inherent structure of motion JPEG2000 codestreams and is used to preserve the semanteme/content of the stream over lossy networks. To achieve …


Strong Mid-Depth Currents And A Deep Cyclonic Gyre In The Gulf Of Mexico, Wilton Sturges, Eric Chassignet, Tal Ezer Nov 2003

Strong Mid-Depth Currents And A Deep Cyclonic Gyre In The Gulf Of Mexico, Wilton Sturges, Eric Chassignet, Tal Ezer

CCPO Publications

The main purpose of this work was to explore the possibility that the deep flow (~2000m) around the edges of the Gulf circulates in a cyclonic, or counter-clockwise direction. The existence of such flow was proposed on theoretical grounds but had not been previously documented. Our results are quite clear that such flow is reliably observed.


Redshift-Distance Survey Of Early-Type Galaxies: Spectroscopic Data, G. Wegner, M. Bernardi, C. N. A. Willmer, L. N. Da Costa Nov 2003

Redshift-Distance Survey Of Early-Type Galaxies: Spectroscopic Data, G. Wegner, M. Bernardi, C. N. A. Willmer, L. N. Da Costa

Dartmouth Scholarship

We present central velocity dispersions and Mg2 line indices for an all-sky sample of ~1178 elliptical and S0 galaxies, of which 984 had no previous measures. This sample contains the largest set of homogeneous spectroscopic data for a uniform sample of elliptical galaxies in the nearby universe. These galaxies were observed as part of the ENEAR project, designed to study the peculiar motions and internal properties of the local early-type galaxies. Using 523 repeated observations of 317 galaxies obtained during different runs, the data are brought to a common zero point. These multiple observations, taken during the many runs …


Habitat Use Of Sympatrically Nesting Fish Crows And American Crows, Brook Lauro, John Tanacredi Ph.D. Nov 2003

Habitat Use Of Sympatrically Nesting Fish Crows And American Crows, Brook Lauro, John Tanacredi Ph.D.

Faculty Works: CERCOM (1977-2016)

We examined habitat use of sympatric Fish Crows (Corvus ossifragus) and American Crows (C. brachyrhynchos) nesting in the vicinity of waterbird breeding locations at the Rockaway Peninsula, New York City. Fish Crows nested significantly more often at natural habitats, including coastal dunes and salt marsh islands; American Crows nested significantly more often at residential and recreational areas. In regard to potential foraging areas, Fish Crows nested closer to waterbird colonies and to the water's edge while American Crows nested closer to a garbage source and to lawns. Fish Crows nested significantly more often in deciduous trees …


Mockup-Driven Fast Prototyping Methodology For Web Requirements Engineering, Jia Zhang, Carl Chang, Jen-Yao Chung Oct 2003

Mockup-Driven Fast Prototyping Methodology For Web Requirements Engineering, Jia Zhang, Carl Chang, Jen-Yao Chung

Jia Zhang

No abstract provided.


Using Information Literacy Standards To Improve Geoscience Courses, Aimee Dechambeau, Ira Sasowsky Oct 2003

Using Information Literacy Standards To Improve Geoscience Courses, Aimee Dechambeau, Ira Sasowsky

Aimee deChambeau

Information literacy (IL) is the set of skills that enables a person to find, evaluate, and use information. Although IL is important in the geosciences, it is hard to teach because the information comes in so many forms. Most geoscience courses include work that implicitly addresses some IL issues. However, because of the importance of IL, it is worthwhile to explicitly include it as part of the curriculum. The Association of College and Research Libraries has developed Information Literacy Standards for Higher Education that may be used to assess an individual's level of information literacy. We introduce a method for …


Mediating Electronic Meetings, Jia Zhang, Carl Chang, Jen-Yao Chung Oct 2003

Mediating Electronic Meetings, Jia Zhang, Carl Chang, Jen-Yao Chung

Jia Zhang

No abstract provided.


Assessment Of Model Development Techniques And Evaluation Methods For Binary Classification In The Credit Industry, Satish Nargundkar, Jennifer Priestley Oct 2003

Assessment Of Model Development Techniques And Evaluation Methods For Binary Classification In The Credit Industry, Satish Nargundkar, Jennifer Priestley

Jennifer L. Priestley

We examine and compare the most prevalent modeling techniques in the credit industry, Linear Discriminant Analysis, Logistic Analysis and the emerging technique of Neural Network modeling. K-S Tests and Classification Rates are typically used in the industry to measure the success in predictive classification. We examine those two methods and a third, ROC Curves, to determine if the method of evaluation has an influence on the perceived performance of the modeling technique. We found that each modeling technique has its own strengths, and a determination of the “best” depends upon the evaluation method utilized and the costs associated with misclassification.


Absorptive Capacity, Causal Ambiguity And Outcome Ambiguity: The Network Effect And Knowledge Transfer Difficulty Among Four Network Forms, Subhashish Samaddar, Jennifer Priestley Oct 2003

Absorptive Capacity, Causal Ambiguity And Outcome Ambiguity: The Network Effect And Knowledge Transfer Difficulty Among Four Network Forms, Subhashish Samaddar, Jennifer Priestley

Jennifer L. Priestley

No abstract is currently available.


Light Propagation In Variable-Refractive-Index Materials With Liquid-Crystal-Infiltrated Microcavities, Bin Wang, Philip Bos, Charles D. Hoke Oct 2003

Light Propagation In Variable-Refractive-Index Materials With Liquid-Crystal-Infiltrated Microcavities, Bin Wang, Philip Bos, Charles D. Hoke

Philip J. Bos

A liquid-crystal-infiltrated microcavity structure is proposed as a variable-refractive-index material. It has the advantages over previously considered nanostructured materials of having a larger phase-angle change and lower driving voltage. Two-dimensional liquid-crystal director and finite-difference time-domain optical simulations are used to select liquid crystal material parameters and optimize the dimension of the microcavity structured material.


Net Charge Fluctuations In Au+Au Collisions At √SNn=130 Gev, Star Collaboration, T.D. Gutierrez Oct 2003

Net Charge Fluctuations In Au+Au Collisions At √SNn=130 Gev, Star Collaboration, T.D. Gutierrez

Physics

We present the results of charged particle fluctuations measurements in Au+Au collisions at √sNN=130 GeV using the STAR detector. Dynamical fluctuations measurements are presented for inclusive charged particle multiplicities as well as for identified charged pions, kaons, and protons. The net charge dynamical fluctuations are found to be large and negative providing clear evidence that positive and negative charged particle production is correlated within the pseudorapidity range investigated. Correlations are smaller than expected based on model-dependent predictions for a resonance gas or a quark-gluon gas which undergoes fast hadronization and freeze-out. Qualitative agreement is found with comparable scaled …


New Results From The Cryogenic Dark Matter Search Experiment, D. S. Akerib, J. Alvaro-Dean, M. S. Armel, M. J. Attisha, L. Baudis, D. A. Bauer, A. I. Bolozdynya, P. L. Brink, R. Bunker, Blas Cabrera, D. O. Caldwell, J. P. Castle, C. L. Chang, R. M. Clarke, M. B. Crisler, P. Crushman, A. K. Davies, R. Dixon, D. D. Driscoll, L. Duong, J. Emes, R. Ferril, R. J. Gaitskell, S. R. Golwala, M. Haldeman, J. Hellmig, M. Hennessey, D. Holmgren, M. E. Huber, S. Kamat, M. Kurylowicz, A. Lu, R. Mahapatra, V. Mandic, J. M. Martinis, P. Meunier, N. Mirabolfathi, S. W. Nam, H. Nelson, R. Nelson, R. W. Ogburn, J. Perales, T. A. Perera, M. C. Perillo Isaac, W. Rau, A. Reisetter, R. R. Ross, T. Saab, B. Sadoulet, J. Sander, C. Savage, R. W. Schnee, D. N. Seitz, T. A. Shutt, G. Smith, A. L. Spadafora, J.-P. F. Thompson, A. Tomada, G. Wang, S. Yellin, Betty A. Young Oct 2003

New Results From The Cryogenic Dark Matter Search Experiment, D. S. Akerib, J. Alvaro-Dean, M. S. Armel, M. J. Attisha, L. Baudis, D. A. Bauer, A. I. Bolozdynya, P. L. Brink, R. Bunker, Blas Cabrera, D. O. Caldwell, J. P. Castle, C. L. Chang, R. M. Clarke, M. B. Crisler, P. Crushman, A. K. Davies, R. Dixon, D. D. Driscoll, L. Duong, J. Emes, R. Ferril, R. J. Gaitskell, S. R. Golwala, M. Haldeman, J. Hellmig, M. Hennessey, D. Holmgren, M. E. Huber, S. Kamat, M. Kurylowicz, A. Lu, R. Mahapatra, V. Mandic, J. M. Martinis, P. Meunier, N. Mirabolfathi, S. W. Nam, H. Nelson, R. Nelson, R. W. Ogburn, J. Perales, T. A. Perera, M. C. Perillo Isaac, W. Rau, A. Reisetter, R. R. Ross, T. Saab, B. Sadoulet, J. Sander, C. Savage, R. W. Schnee, D. N. Seitz, T. A. Shutt, G. Smith, A. L. Spadafora, J.-P. F. Thompson, A. Tomada, G. Wang, S. Yellin, Betty A. Young

Physics

Using improved Ge and Si detectors, better neutron shielding, and increased counting time, the Cryogenic Dark Matter Search (CDMS) experiment has obtained stricter limits on the cross section of weakly interacting massive particles (WIMPs) elastically scattering from nuclei. Increased discrimination against electromagnetic backgrounds and reduction of the neutron flux confirm WIMP-candidate events previously detected by CDMS were consistent with neutrons and give limits on spin-independent WIMP interactions which are >2× lower than previous CDMS results for high WIMP mass, and which exclude new parameter space for WIMPs with mass between 8 and 20 GeV/c2 .


Distance-Dependent Electron Hopping Conductivity And Nanoscale Lithography Of Chemically-Linked Gold Monolayer Protected Cluster Films, Francis P. Zamborini, Laura E. Smart, Michael C. Leopold, Royce W. Murray Oct 2003

Distance-Dependent Electron Hopping Conductivity And Nanoscale Lithography Of Chemically-Linked Gold Monolayer Protected Cluster Films, Francis P. Zamborini, Laura E. Smart, Michael C. Leopold, Royce W. Murray

Chemistry Faculty Publications

Films of monolayer protected Au clusters (MPCs) with mixed alkanethiolate and ω-carboxylate alkanethiolate monolayers, linked together by carboxylate–Cu2+–carboxylate bridges, exhibit average edge-to-edge cluster spacings that vary with the numbers of methylene segments in the alkanethiolate ligand as determined by a combined atomic force microscopy (AFM)/UV-Vis spectroscopy method. The electronic conductivity (σEL) of dry films is exponentially dependent on the cluster spacing, consistent with electron tunneling through the alkanethiolate chains and non-bonded contacts between those chains on individual, adjacent MPCs. The calculated electronic coupling factor (β) for tunneling between MPCs is 1.2 Å−1, which is similar to …


Developing A Sensing System For The Measurement Of Oxygen Concentration In Liquid Pb-Bi Eutectic: Quarterly Progress Report (Aug. 01 – Oct. 31, 2003), Yingtao Jiang, Bingmei Fu Oct 2003

Developing A Sensing System For The Measurement Of Oxygen Concentration In Liquid Pb-Bi Eutectic: Quarterly Progress Report (Aug. 01 – Oct. 31, 2003), Yingtao Jiang, Bingmei Fu

Transmutation Sciences Materials (TRP)

The experimental setup designed and manufactured in UNLV was shipped to LANL in early Aug. One student has been working in LANL to conduct the experiment since then. In the meantime, one new Ph. D. student has started to run the simulation for transport in oxygen mixing. In Oct., a professional has been hired to work in both experimental and the theoretical studies pertaining to the proposed work.


Semi-Parametric Box-Cox Power Transformation Models For Censored Survival Observations, Tianxi Cai, Lu Tian, L. J. Wei Oct 2003

Semi-Parametric Box-Cox Power Transformation Models For Censored Survival Observations, Tianxi Cai, Lu Tian, L. J. Wei

Harvard University Biostatistics Working Paper Series

No abstract provided.


Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials: Quarterly Progress Report (June 1 – August 31, 2003), Ajit K. Roy, Brendan O'Toole Oct 2003

Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials: Quarterly Progress Report (June 1 – August 31, 2003), Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

As indicated in the original proposal, the primary objective of this task is to evaluate the effect of hydrogen on environment-assisted cracking of candidate target materials for applications in spallationneutron- target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The materials selected for evaluation and characterization are martensitic stainless steels including Alloy HT-9, Alloy EP 823 and Type 422 stainless steel. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of these materials are being evaluated in aqueous environments of interest using tensile specimens under constant load and slow-strain-rate (SSR) conditions. …


Development Of A Mechanistic Understanding Of High-Temperature Deformation Of Alloy Ep-823 For Transmutation Applications: Quarterly Progress Report (June 01 – Aug 31, 2003), Ajit K. Roy, Brendan O'Toole Oct 2003

Development Of A Mechanistic Understanding Of High-Temperature Deformation Of Alloy Ep-823 For Transmutation Applications: Quarterly Progress Report (June 01 – Aug 31, 2003), Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The purpose of this project is to evaluate the elevated temperature tensile properties of Alloy EP-823, a leading target material for accelerator-driven waste transmutation applications. This Alloy has been proven to be an excellent structural material to contain the lead-bismuth-eutectic (LBE) nuclear coolant needed for fast spectrum operations. Very little data exist in the open literature on the tensile properties of this Alloy. The test material will be thermally treated prior to the evaluation of its tensile properties at temperatures relevant to the transmutation applications. The deformation characteristics of tensile specimens, upon completion of testing, will be evaluated by surface …


Use Of Positron Annihilation Spectroscopy For Stress-Strain Measurements: Quarterly Progress Report (June 01 – August 31, 2003), Ajit K. Roy Oct 2003

Use Of Positron Annihilation Spectroscopy For Stress-Strain Measurements: Quarterly Progress Report (June 01 – August 31, 2003), Ajit K. Roy

Transmutation Sciences Materials (TRP)

The purpose of this collaborative research project involving the University of Nevada Las Vegas (UNLV), the Idaho State University (ISU), and the Los Alamos National Laboratory (LANL) is to evaluate the feasibility of determining residual stresses in cold-worked, plastically-deformed (bent), and welded materials using a nondestructive method based on positron annihilation spectroscopy (PAS). This technique uses γ-rays from a small MeV electron Linac to generate positrons inside the sample via pair production. This method is known to have capabilities of characterizing defects in thick specimens that could not be accomplished by conventional positron technique or other nondestructive methods. The generated …


Plug Beebee Station Into Producing Hydrogen Power, Roman Press, Marianne A. Buehler Oct 2003

Plug Beebee Station Into Producing Hydrogen Power, Roman Press, Marianne A. Buehler

Library Faculty Publications

No abstract provided.


Measurement Of Deeply Virtual Compton Scattering At Hera, S. Chekanov, M. Derrick, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan Oct 2003

Measurement Of Deeply Virtual Compton Scattering At Hera, S. Chekanov, M. Derrick, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan

Faculty Publications

The cross-section for deeply virtual Compton scattering in the reaction ep → eγp has been measured with the ZEUS detector at HERA using integrated luminosities of 95.0 pb-1 of e+p and 16.7 pb-1 of e-p collisions. Differential cross-sections are presented as a function of the exchanged-photon virtuality, Q2, and the centre-of-mass energy, W, of the γ*p system in the region 5 < Q2 < 100 GeV2 and 40 < W < 140 GeV. The measured cross-sections rise steeply with increasing W. The measurements are compared to QCD-based calculations. © 2003 Elsevier B.V. All rights reserved.


What Can Semantics Do For Bioinformatics?, Amit P. Sheth Oct 2003

What Can Semantics Do For Bioinformatics?, Amit P. Sheth

Kno.e.sis Publications

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Unification Of Variance Components And Haseman-Elston Regression For Quantitative Trait Linkage Analysis, Wei-Min Chen, Karl W. Broman, Kung-Yee Liang Oct 2003

Unification Of Variance Components And Haseman-Elston Regression For Quantitative Trait Linkage Analysis, Wei-Min Chen, Karl W. Broman, Kung-Yee Liang

Johns Hopkins University, Dept. of Biostatistics Working Papers

Two of the major approaches for linkage analysis with quantitative traits in humans include variance components and Haseman-Elston regression. Previously, these have been viewed as quite separate methods. We describe a general model, fit by use of generalized estimating equations (GEE), for which the variance components and Haseman-Elston methods (including many of the extensions to the original Haseman-Elston method) are special cases, corresponding to different choices for a working covariance matrix. We also show that the regression-based test of Sham et al.(2002) is equivalent to a robust score statistic derived from our GEE approach. These results have several important implications. …


Evaluation Of Adsorption Effects On Measurements Of Ammonia, Acetic Acid, And Methanol, Robert J. Yokelson, Ted J. Christian, Isaac T. Bertschi, Wei M. Hao Oct 2003

Evaluation Of Adsorption Effects On Measurements Of Ammonia, Acetic Acid, And Methanol, Robert J. Yokelson, Ted J. Christian, Isaac T. Bertschi, Wei M. Hao

Chemistry and Biochemistry Faculty Publications

[1] We examined how adsorption and desorption of gases from inlets and a cell could affect the accuracy of closed-cell FTIR measurements of carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), nitric oxide (NO), nitrogen dioxide (NO2), methanol (CH3OH), acetic acid (CH3COOH), and ammonia (NH3). When standards were delivered to the cell through a stainless steel inlet, temporarily reduced transmission was observed for CH3OH and NH3. However, a halocarbon wax coated inlet (normally used on the system) had excellent transmission (comparable to room temperature …


Smooth Quantile Ratio Estimation, Francesca Dominici, Leslie Cope, Daniel Q. Naiman, Scott L. Zeger Oct 2003

Smooth Quantile Ratio Estimation, Francesca Dominici, Leslie Cope, Daniel Q. Naiman, Scott L. Zeger

Johns Hopkins University, Dept. of Biostatistics Working Papers

In a study of health care expenditures attributable to smoking, we seek to compare the distribution of medical costs for persons with lung cancer or chronic obstructive pulmonary disease (cases) to those without (controls) using a national survey which includes hundreds of cases and thousands of controls. The distribution of costs is highly skewed toward larger values, making estimates of the mean from the smaller sample dependent on a small fraction of the biggest values. One approach to deal with the smaller sample is to rely on a simple parametric model such as the log-normal, but this makes the undesirable …


Hierarchical Bivariate Time Series Models: A Combined Analysis Of The Effects Of Particulate Matter On Morbidity And Mortality, Francesca Dominici, Antonella Zanobetti, Scott L. Zeger, Joel Schwartz, Jonathan M. Samet Oct 2003

Hierarchical Bivariate Time Series Models: A Combined Analysis Of The Effects Of Particulate Matter On Morbidity And Mortality, Francesca Dominici, Antonella Zanobetti, Scott L. Zeger, Joel Schwartz, Jonathan M. Samet

Johns Hopkins University, Dept. of Biostatistics Working Papers

In this paper we develop a hierarchical bivariate time series model to characterize the relationship between particulate matter less than 10 microns in aerodynamic diameter (PM10) and both mortality and hospital admissions for cardiovascular diseases. The model is applied to time series data on mortality and morbidity for 10 metropolitan areas in the United States from 1986 to 1993. We postulate that these time series should be related through a shared relationship with PM10.

At the first stage of the hierarchy, we fit two seemingly unrelated Poisson regression models to produce city-specific estimates of the log relative rates of mortality …


Some Combinatorial Design In Vlsi Architectures And Statistics., Soumen Maity Dr. Oct 2003

Some Combinatorial Design In Vlsi Architectures And Statistics., Soumen Maity Dr.

Doctoral Theses

In this dissertation, we consider the following combinatorial problems: some character- ization, enumeration, construction and optimization problems in both VLSI linear and VLSI two-dimensional arrays; and construction of two combinatorial designs as used by statisticians: nearly strongly balanced uniform repeated measurements designs (NSBUR- MDs) and balanced near uniform repeated measurements designs (BNURMDS). We give below, chapter-wise, the problems considered and a brief outline of the solutions.1.1 Enumerating Catastrophic Fault Patterns in VLSI Linear Arrays with Bidirectional or Unidirectional LinksSystolic systems consist, of a large mimber of identical and elementary processing element locally conuccted in a regular fashion. Each element receives …


A Probability-Based Similarity Measure For Saupe Alignment Tensors With Applications To Residual Dipolar Couplings In Nmr Structural Biology, Anthony K. Yan, Christopher J. Langmead, Bruce Randall Donald Oct 2003

A Probability-Based Similarity Measure For Saupe Alignment Tensors With Applications To Residual Dipolar Couplings In Nmr Structural Biology, Anthony K. Yan, Christopher J. Langmead, Bruce Randall Donald

Computer Science Technical Reports

High-throughput NMR structural biology and NMR structural genomics pose a fascinating set of geometric challenges. A key bottleneck in NMR structural biology is the resonance assignment problem. We seek to accelerate protein NMR resonance assignment and structure determination by exploiting a priori structural information. In particular, a method known as Nuclear Vector Replacement (NVR) has been proposed as a method for solving the assignment problem given a priori structural information [24,25]. Among several different kinds of input data, NVR uses a particular type of NMR data known as residual dipolar couplings (RDCs). The basic physics of residual dipolar couplings tells …


Dynamics Underlying Fully Differential Cross Sections For Fast C⁶⁺ + He Collisions, Ronald E. Olson, J. Fiol Oct 2003

Dynamics Underlying Fully Differential Cross Sections For Fast C⁶⁺ + He Collisions, Ronald E. Olson, J. Fiol

Physics Faculty Research & Creative Works

Single ionization of helium by impact of 100 MeV u-1 C6+ ions is investigated using the three-body classical trajectory Monte Carlo method. Fully differential cross section calculations are compared to recently published data for ionized electrons emitted both in the scattering plane, and in the plane perpendicular to it that contains the initial velocity. the present calculations show good agreement with the experimental data, and improve upon continuum-distorted-wave results. the collision mechanisms that lead to the different structures observed in the fully differential cross sections are investigated and include those of the binary and recoil peaks for in-plane …


Ancient Maize From Chacoan Great Houses: Where Was It Grown?, Larry Benson, Linda Cordell, Kirk Vincent, Howard E. Taylor, John Stein, G. Lang Farmer, U.S. Geological Survey Oct 2003

Ancient Maize From Chacoan Great Houses: Where Was It Grown?, Larry Benson, Linda Cordell, Kirk Vincent, Howard E. Taylor, John Stein, G. Lang Farmer, U.S. Geological Survey

United States Geological Survey: Staff Publications

In this article, we compare chemical (87Sr/86Sr and elemental) analyses of archaeological maize from dated contexts within Pueblo Bonito, Chaco Canyon, New Mexico, to potential agricultural sites on the periphery of the San Juan Basin. The oldest maize analyzed from Pueblo Bonito probably was grown in an area located 80 km to the west at the base of the Chuska Mountains. The youngest maize came from the San Juan or Animas river floodplains 90 km to the north. This article demonstrates that maize, a dietary staple of southwestern Native Americans, was transported over considerable distances in …