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2002

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Articles 31 - 60 of 3435

Full-Text Articles in Physical Sciences and Mathematics

Skill Acquisition In Transfer Of Manipulation Skills From Human To Machine Through A Haptic Virtual Environment, Y. Chen, F. Naghdy Dec 2002

Skill Acquisition In Transfer Of Manipulation Skills From Human To Machine Through A Haptic Virtual Environment, Y. Chen, F. Naghdy

Faculty of Informatics - Papers (Archive)

A new paradigm for programming a robotics manipulator is developed. It is intended that the teaching of the machine will begin with the necessary skills being demonstrated by the human operator in a virtual environment with tactile sensing (haptics). Position and contact force and torque data generated in the virtual environment combined with a priori knowledge about the task is used to identify and learn the skills in the newly demonstrated tasks and then to reproduce them in the robotics system. The peg-in-hole insertion problem is used as a case study. The overall concept is described. The methodologies developed to …

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Blackbirds And Corn In Ohio, Richard A. Dolbeer Dec 2002

Blackbirds And Corn In Ohio, Richard A. Dolbeer

United States Department of Agriculture Wildlife Services: Staff Publications

Damage to corn by blackbirds (Icteridae) has been an economic problem throughout historical times in North America. Ohio, with the highest nesting season population density of red-winged blackbirds (Agelaius phoeniceus) in North America and large acreages of corn, has been a key State in this conflict. Surveys of damage from 1968 to 1979 revealed that blackbirds annually destroyed less than 1% of the corn crops in Ohio, a 4- to 6-million dollar loss at 1979 prices. This total dollar loss is somewhat misleading because of the uneven distribution of damage among fields. Over 97% of the cornfields in Ohio receive …

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Evaluation Of Lasers To Disperse American Crows, Corvus Brachyrhynchos, From Urban Night Roosts, W.P. Gorenzel, B. F. Blackwell, G.D. Simmons, T.P. Salmon, R.A. Dolbeer Dec 2002

Evaluation Of Lasers To Disperse American Crows, Corvus Brachyrhynchos, From Urban Night Roosts, W.P. Gorenzel, B. F. Blackwell, G.D. Simmons, T.P. Salmon, R.A. Dolbeer

United States Department of Agriculture Wildlife Services: Staff Publications

American crows (Corvus brachyrhynchos) have a long history of causing agricultural damage in North America. Shooting and bombing at crow night roosts have been employed to reduce such damage. Most roosts were located in rural locations, but in the latter half of the 1900s crows began to roost in urban locations. Urban crow roosts are presently a nationwide problem in the United States. Thousands of crows at a roost create problems for businesses and residents. Improved control techniques are needed. Lasers have been used in Europe to scare and disperse birds but the technique has only recently received formal testing. …

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A Simulation Study Of Space-Based Observations Of Gravity Waves In The Airglow Using Observed Aloha-93 Wave Parameters, Michael P. Hickey Ph.D., J. S. Brown Dec 2002

A Simulation Study Of Space-Based Observations Of Gravity Waves In The Airglow Using Observed Aloha-93 Wave Parameters, Michael P. Hickey Ph.D., J. S. Brown

Publications

We use gravity wave parameters derived from the ALOHA-93 campaign to model four gravity waves in airglow emissions as observed from the ground to numerically predict whether these waves could have been observed from space. In spite of encountering critical levels, some waves may still be observed in the airglow provided the critical level lies within the airglow emission region. One of the four waves experiences a critical level in the lower region of an airglow layer such that the disturbance to the volume emission rate would be effectively limited to a short distance along a satellite line of sight. …

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Invariant Sets And Inverse Limits, William Thomas Ingram Dec 2002

Invariant Sets And Inverse Limits, William Thomas Ingram

Mathematics and Statistics Faculty Research & Creative Works

In this paper we investigate the nature of inverse limits from the point of view of invariant sets. We then introduce a special class of examples of inverse limits on [0,1] using Markov bonding maps determined by members of the group of permutations on n elements. © 2002 Elsevier Science B.V. All rights reserved.

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Isotropization In Brane Gas Cosmology, Scott Watson, Robert H. Brandenberger Dec 2002

Isotropization In Brane Gas Cosmology, Scott Watson, Robert H. Brandenberger

Physics - All Scholarship

Brane Gas Cosmology (BGC) is an approach to unifying string theory and cosmology in which matter is described by a gas of strings and branes in a dilaton gravity background. The Universe is assumed to start out with all spatial dimensions compact and small. It has previously been shown that in this context, in the approximation of neglecting inhomogeneities and anisotropies, there is a dynamical mechanism which allows only three spatial dimensions to become large. However, previous studies do not lead to any conclusions concerning the isotropy or anisotropy of these three large spatial dimensions. Here, we generalize the equations …

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Recurrent Events Analysis In The Presence Of Time Dependent Covariates And Dependent Censoring, Maja Miloslavsky, Sunduz Keles, Mark J. Van Der Laan, Steve Butler Dec 2002

Recurrent Events Analysis In The Presence Of Time Dependent Covariates And Dependent Censoring, Maja Miloslavsky, Sunduz Keles, Mark J. Van Der Laan, Steve Butler

U.C. Berkeley Division of Biostatistics Working Paper Series

Recurrent events models have lately received a lot of attention in the literature. The majority of approaches discussed show the consistency of parameter estimates under the assumption that censoring is independent of the recurrent events process of interest conditional on the covariates included into the model. We provide an overview of available recurrent events analysis methods, and present an inverse probability of censoring weighted estimator for the regression parameters in the Andersen-Gill model that is commonly used for recurrent event analysis. This estimator remains consistent under informative censoring if the censoring mechanism is estimated consistently, and generally improves on the …

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Construction Of Counterfactuals And The G-Computation Formula, Zhuo Yu, Mark J. Van Der Laan Dec 2002

Construction Of Counterfactuals And The G-Computation Formula, Zhuo Yu, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

Robins' causal inference theory assumes existence of treatment specific counterfactual variables so that the observed data augmented by the counterfactual data will satisfy a consistency and a randomization assumption. Gill and Robins [2001] show that the consistency and randomization assumptions do not add any restrictions to the observed data distribution. In particular, they provide a construction of counterfactuals as a function of the observed data distribution. In this paper we provide a construction of counterfactuals as a function of the observed data itself. Our construction provides a new statistical tool for estimation of counterfactual distributions. Robins [1987b] shows that the …

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Stop The Century--We’Re Not Ready!, Leon Lederman Dec 2002

Stop The Century--We’Re Not Ready!, Leon Lederman

IMSA Great Minds Program ®

The distinguished Nobel Laureate and contributing author of the newly released Science Literacy for the Twenty-first Century and author of The God Particle will explore how science and technology serve as the drivers for 21st Century changes in our social, political and economic lives. Profits and conveniences made by deployment of new knowledge force the issue of whether such deployment is in society’s best long-term interest. The need grows exponentially for the voting public in our democratic society to play a significant role in making decisions. Lederman discusses whether we can devise a feasible educational system that will produce high …

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Ecotones: The Heartbeat Of Huxley, 2002, Fall, Issue 09, Laurel Eddy, Huxley College Of The Environment, Western Washington University Dec 2002

Ecotones: The Heartbeat Of Huxley, 2002, Fall, Issue 09, Laurel Eddy, Huxley College Of The Environment, Western Washington University

Historical Collection of Huxley Newsletters

No abstract provided.

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Biaxial Strain-Modified Valence And Conduction Band Offsets Of Zinc-Blende Gan, Gap, Gaas, Inn, Inp, And Inas, And Optical Bowing Of Strained Epitaxial Ingan Alloys, Gus L. W. Hart, P. R. C. Kent, Alex Zunger Dec 2002

Biaxial Strain-Modified Valence And Conduction Band Offsets Of Zinc-Blende Gan, Gap, Gaas, Inn, Inp, And Inas, And Optical Bowing Of Strained Epitaxial Ingan Alloys, Gus L. W. Hart, P. R. C. Kent, Alex Zunger

Faculty Publications

Using density-functional calculations, we obtain the (001) biaxial strain dependence of the valence and conduction band energies of GaN, GaP, GaAs, InN, InP, and InAs. The results are fit to a convenient-to-use polynomial and the fits provided in tabular form. Using the calculated biaxial deformation potentials in large supercell empirical psuedopotential calculations, we demonstrate that epitaxial strain reduces the InGaN alloy bowing coefficient compared to relaxed bulk alloys.

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Implications Of Mbti In Software Engineering Education, Luiz Fernando Capretz Dec 2002

Implications Of Mbti In Software Engineering Education, Luiz Fernando Capretz

Electrical and Computer Engineering Publications

A number of approaches exist to aid the understanding of individual differences and their effects on teaching and learning. Educators have been using the Myers-Briggs Type Indicator (MBTI) to understand differences in learning styles and to develop teaching methods that cater for the various personality styles. Inspired by the MBTI, we developed a range of practices for effective teaching and learning in a software engineering course. Our aim is to reach every student, but in different ways, by devising various teaching approaches.

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Water Current, Volume 34, No. 6. December 2002 Dec 2002

Water Current, Volume 34, No. 6. December 2002

Water Current Newsletter

• UNL Aquaculturist Sees Fish Farming Niche in Empty Hog Barns by Steve Ress

• From the Director

• Meet the Faculty

• The Army Corps’ Missouri River Mission by Brig. Gen. David A. Fastabend

• Water News Briefs

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Autoregressive Moving Average Models Of Conifer Crown Profiles, Samantha J. Gill, Gregory S. Biging Dec 2002

Autoregressive Moving Average Models Of Conifer Crown Profiles, Samantha J. Gill, Gregory S. Biging

Natural Resources Management and Environmental Sciences

A time-series autoregressive moving average (ARMA) approach was used to develop stochastic models of tree crown profiles for five conifer species of the Sierran mixed conifer habitat type. Models consisted of three components: (1) a polynomial trend; (2) an ARMA model; and (3) random error. A Bayesian information criterion was used to evaluate alternative models. It was found that 70% of the crown profiles could be modeled using first-order ARMA [AR(1) or MA(1)] models, and that an additional 25% could be modeled using a white noise model [(AR(0)]. When the coefficients of the ARMA models were statistically significant, the models …

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Measuring Surface Chemical Properties Of Soil Using Flow Calorimetry, R. D. Rhue, Chip Appel, Nadine Kabengi Dec 2002

Measuring Surface Chemical Properties Of Soil Using Flow Calorimetry, R. D. Rhue, Chip Appel, Nadine Kabengi

Earth and Soil Sciences

Flow calorimetry, which is ideally suited for measuring reactions occurring at the liquid/solid interface, has been used to study the surface chemistry of many types of solids, but little use of it has been made in the study of surface reactions of soils. The purpose of this study was to demonstrate the application of flow calorimetry to the study of two fundamental soil chemical processes, namely cation exchange and phosphate sorption. Surface horizon samples of a Typic Acrorthox and a Typic Tropohumult from Puerto Rico, a strong acid cation exchange resin (Dowex 50W-8), and an amorphous Al(OH)3 were used. …

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Heats Of K/Ca And K/Pb Exchange In Two Tropical Soils As Measured By Flow Calorimetry, Chip Appel, Dean Rhue, Lena Ma, Bill Reve Dec 2002

Heats Of K/Ca And K/Pb Exchange In Two Tropical Soils As Measured By Flow Calorimetry, Chip Appel, Dean Rhue, Lena Ma, Bill Reve

Earth and Soil Sciences

Flow calorimetry can provide useful information about surface chemical reactions in soils that cannot be obtained readily by other methods. When flow calorimetry is conducted over a range of surface coverages, different sorption heats can be calculated to yield information about how binding energies vary with coverage, i.e., surface heterogeneity. The purpose of this study was to determine heats of exchange for K/Ca and K/Pb systems using flow calorimetry and to evaluate the degree of surface heterogeneity with respect to cation exchange. Surface horizon samples from a Typic Acrorthox and Typic Tropohumult from Puerto Rico were used. Lead was adsorbed …

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Historical Changes In Mid-Water Stands Of Common Reed In The Winnebago Pool Lakes, Wisconsin, Anthony O. Gabriel, Leo R. Bodensteiner Dec 2002

Historical Changes In Mid-Water Stands Of Common Reed In The Winnebago Pool Lakes, Wisconsin, Anthony O. Gabriel, Leo R. Bodensteiner

All Faculty Scholarship for the College of the Sciences

Despite the tolerance of common reed grass to environmental extremes, mid-water stands in the Winnebago pool lakes of central Wisconsin appear to be diminishing. Formerly occupying shoreline locations, water level manipulations subsequent to dam construction beginning in the 1850's have isolated reed stands off shore. These stands have persisted but casual observations indicate that stand size has been declining. To address this perception we obtained an approximately decadal series of aerial photographs dating back to 1937 for four stands in Lake Poygan. Annual records were available for 1986–94. Using image analysis software, we determined shape and size metrics. Changes in …

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News From Cart, Michael A. Krol, Julia Stakhnevich Dec 2002

News From Cart, Michael A. Krol, Julia Stakhnevich

Bridgewater Review

No abstract provided.

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Two-Dimensional Imaging Of Neutral Alkali Atom Samples Using Surface Ionization, Katharina Gillen-Christandl, Gregory P. Lafyatis, Andrei Modoran, Tung-Hsiu Shih Dec 2002

Two-Dimensional Imaging Of Neutral Alkali Atom Samples Using Surface Ionization, Katharina Gillen-Christandl, Gregory P. Lafyatis, Andrei Modoran, Tung-Hsiu Shih

Physics

We describe the design and characterization of a high resolution, high efficiency detector for two-dimensional imaging of neutral atoms. Incident atoms are surface-ionized by a tungsten-coated hot ribbon and the resulting ions are accelerated into a microchannel plate detector with a phosphor screen output. With this design we can detect individual alkali and other low ionization potential atoms and molecules with a spatial resolution of ∼ 20 μm. We find backgrounds on the order of 30 Hz over an active detection region of 20 mm2, a time response of ⩽ 1/30 s, and a detection efficiency of …

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Poly(Meta-Phenylene Isophthalamide) Nanofibers: Coating And Post Processing, Wenxia Liu, Matthew Graham, Edward A. Evans, Darrell H. Reneker Dec 2002

Poly(Meta-Phenylene Isophthalamide) Nanofibers: Coating And Post Processing, Wenxia Liu, Matthew Graham, Edward A. Evans, Darrell H. Reneker

Chemical, Biomolecular, and Corrosion Engineering Faculty Research

Electrospun nanofibers have applications in the areas of filtration, composites; biomaterials, and electronics. Controlling the surface properties of these nanofibers is important for many applications. Nanofibers can also be used as unique substrates for observing the growth of deposited films and creating nanoscale structures. In this work, electrospun poly(meta-phenylene isophthalamide) (MPD-I) nanofibers were used as substrates for creating nanoscale structures out of carbon-based materials and metals. MPD-I was used because it can be electrospun into nanofibers with diameters smaller than 10 nm and it has good thermal stability. MPD-I nanofibers were coated with carbon, copper, and aluminum using plasma enhanced …

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High-Energy Ball Milling Of Polymers, Jabari Robinson Dec 2002

High-Energy Ball Milling Of Polymers, Jabari Robinson

Electronic Dissertations and Theses

With metallic materials, the mechanism of milling is generally regarded as a combination of fracturing and cold-welding of powder particles. The same general mechanism is expected to apply polymers, but some aspects of the mechanism may be different for polymers due their chainlike molecular nature, lower moduli, and higher sensitivity to temperature. In spite of some potential problems some researchers have recently demonstrated that milling can be used to produce polymers and blends with acceptable mechanical properties. C. Bai and associates used high-energy ball milling at three temperatures on poly (ethylene terephthalate) and produced favorable results. Spontak et. al. cryogenically …

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Effects Of Germanium On The Electronic Transport Mechanism In Co20 (Cu-XGeX)80 Nanogranular Ribbons, J. He, Z. D. Zhang, J. Ping Liu, David J. Sellmyer Dec 2002

Effects Of Germanium On The Electronic Transport Mechanism In Co20 (Cu-XGeX)80 Nanogranular Ribbons, J. He, Z. D. Zhang, J. Ping Liu, David J. Sellmyer

David Sellmyer Publications

The dependency of giant magnetoresistance (GMR) on the nonmagnetic matrix in nanogranular Co20 (Cu1-xGex)80 ribbons was studied. When the matrix Cu is substituted with semiconductor Ge, the magnetoresistance transitioned from negative to positive at low temperatures. The positive GMR effect is closely related to the quantity of Co/Co3Ge2/Co junctionlike configurations. This result provides evidence for the competition between two types of electronic transport mechanisms in the magnetic granular ribbons: (i) electronic spin-dependent scattering, inducing a negative magnetoresistance and (ii) Coulomb blockade of the electronic tunneling, inducing a positive magnetoresistance.

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Osaka University: A Focus Of Polymer Science: 70th Anniversary Celebration, Otto Vogl, Koichi Hatada Dec 2002

Osaka University: A Focus Of Polymer Science: 70th Anniversary Celebration, Otto Vogl, Koichi Hatada

Otto Vogl

No abstract provided.

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Personalities In Polymer Science: Cover Page, Title Page, Introduction, And List Of Articles, Otto Vogl Dec 2002

Personalities In Polymer Science: Cover Page, Title Page, Introduction, And List Of Articles, Otto Vogl

Otto Vogl

A compilation of articles with short biographies of the scientists who played leading roles in the field and provided the basis of Polymer Science and Technology throughout the 20th century.

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Epibiotic Sponges On The Scallops Chlamys Hastata And Chlamys Rubida: Increased Survival In A High-Sediment Environment, Duncan O. Burns, Brian L. Bingham Dec 2002

Epibiotic Sponges On The Scallops Chlamys Hastata And Chlamys Rubida: Increased Survival In A High-Sediment Environment, Duncan O. Burns, Brian L. Bingham

Environmental Sciences Faculty and Staff Publications

The small free-swimming scallops, Chlamys hastata and Chlamys rubida, are frequently encrusted by the sponges Mycale adhaerens and Myxilla incrustans. It is unclear why this association exists. We hypothesized that living on scallop valves increases sponge survival by reducing the effects of sediment accumulation. Scallops were collected to measure correlations between sediment load and encrusting sponge mass. In the laboratory, the survival of sponges on living scallops and empty scallop valves was measured. Time-lapse video was used to quantify spontaneous swimming and clapping of C. hastata. In the field, both scallop size and sponge mass were significantly greater …

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Sign-Changing And Multiple Solutions For The P-Laplacian, Siegfried Carl, Kanishka Perera Dec 2002

Sign-Changing And Multiple Solutions For The P-Laplacian, Siegfried Carl, Kanishka Perera

Mathematics and System Engineering Faculty Publications

We obtain a positive solution, a negative solution, and a sign-changing solution for a class of p-Laplacian problems with jumping nonlinearities using variational and super-subsolution methods.

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Report On The Oregon Ballast Water Management Program In 2002, Jordan Vinograd, Mark Sytsma Dec 2002

Report On The Oregon Ballast Water Management Program In 2002, Jordan Vinograd, Mark Sytsma

Center for Lakes and Reservoirs Publications and Presentations

This report documents the efficacy of the first ten months of the Oregon Ballast Water Management Program, which was established by SB 895 during the 2001 legislative session. The Oregon Ballast Water Management Program was initiated to address the introduction of aquatic nuisance species via discharge of ballast water from ships. The Program reflects the Oregon Legislature’s recognition of the potential for aquatic nuisance species to cause economic and environmental damage to the State. Oregon Laws 2001, Chapter 722 (Appendix A), required that owners and operators of certain vessels entering Oregon waters must report the time and place ballast water …

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N Coupled Nonlinear Schrödinger Equations: Special Set And Applications To N=3, Foek T. Hioe Dec 2002

N Coupled Nonlinear Schrödinger Equations: Special Set And Applications To N=3, Foek T. Hioe

Physics Faculty/Staff Publications

Analytic solutions for a special set of N coupled nonlinear Schrödinger equations characterized by 2N interaction types are presented for N = 1–3. They provide an overview of the important role played by nonlinear couplings

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Exclusion Limits On The Wimp-Nucleon Cross Section From The Cryogenic Dark Matter Search, D. Abrams, D. S. Akerib, M. S. Armel-Funkhouser, L. Baudis, D. A. Bauer, A. Bolozdynya, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, J. P. Castle, C. L. Chang, R. M. Clarke, M. B. Crisler, R. Dixon, D. Driscoll, S. Eichblatt, R. J. Gaitskell, S. R. Golwala, E. E. Haller, J. Hellmig, D. Holmgren, M. E. Huber, S. Kamat, A. Lu, V. Mandic, J. M. Martinis, P. Meunier, S. W. Nam, H. Nelson, T. A. Perera, M. C. Perillo Isaac, W. Rau, R. R. Ross, T. Saab, B. Sadoulet, J. Sander, R. W. Schnee, T. Shutt, A. Smith, A. H. Sonnenschein, A. L. Spadafora, G. Wang, S. Yellin, Betty A. Young Dec 2002

Exclusion Limits On The Wimp-Nucleon Cross Section From The Cryogenic Dark Matter Search, D. Abrams, D. S. Akerib, M. S. Armel-Funkhouser, L. Baudis, D. A. Bauer, A. Bolozdynya, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, J. P. Castle, C. L. Chang, R. M. Clarke, M. B. Crisler, R. Dixon, D. Driscoll, S. Eichblatt, R. J. Gaitskell, S. R. Golwala, E. E. Haller, J. Hellmig, D. Holmgren, M. E. Huber, S. Kamat, A. Lu, V. Mandic, J. M. Martinis, P. Meunier, S. W. Nam, H. Nelson, T. A. Perera, M. C. Perillo Isaac, W. Rau, R. R. Ross, T. Saab, B. Sadoulet, J. Sander, R. W. Schnee, T. Shutt, A. Smith, A. H. Sonnenschein, A. L. Spadafora, G. Wang, S. Yellin, Betty A. Young

Physics

The Cryogenic Dark Matter Search (CDMS) employs low-temperature Ge and Si detectors to search for weakly interacting massive particles (WIMPs) via their elastic-scattering interactions with nuclei while discriminating against interactions of background particles. For recoil energies above 10 keV, events due to background photons are rejected with >99.9% efficiency, and surface events are rejected with >95% efficiency. The estimate of the background due to neutrons is based primarily on the observation of multiple-scatter events that should all be neutrons. Data selection is determined primarily by examining calibration data and vetoed events. Resulting efficiencies should be accurate to ∼10%. Results of …

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Water Resources Year In Review - Winter 2002, Annis Water Resources Institute Dec 2002

Water Resources Year In Review - Winter 2002, Annis Water Resources Institute

AWRI Reviews

No abstract provided.

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