Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

2001

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 3001 - 3030 of 3030

Full-Text Articles in Physical Sciences and Mathematics

Mental Rotation Of Objects Retrieved From Memory: An Fmri Study Of Spatial Processing, Marcel Just, Patricia Carpenter, Mandy Maguire, Vaibhav Diwadkar, Stephanie Mcmains Dec 2000

Mental Rotation Of Objects Retrieved From Memory: An Fmri Study Of Spatial Processing, Marcel Just, Patricia Carpenter, Mandy Maguire, Vaibhav Diwadkar, Stephanie Mcmains

Marcel Adam Just

No abstract provided.


Imaging Fault Structure Of The 1995 Kozani-Grevena Earthquake Sequence, Greece Using High Precision Aftershock Locations, Phillip Resor, G Beroza, David Pollard Dec 2000

Imaging Fault Structure Of The 1995 Kozani-Grevena Earthquake Sequence, Greece Using High Precision Aftershock Locations, Phillip Resor, G Beroza, David Pollard

Phillip G Resor

The May 13, 1995 Kozani-Grevena earthquake (Mw=6.5) is a natural laboratory for studying crustal normal fault systems. The event and its aftershocks have been well observed geodetically, seismically, and geologically, providing an opportunity to integrate data sets to create a detailed subsurface fault model and investigate triggering and deformation associated with a large normal fault earthquake. Previous modeling of the earthquake has focused primarily on single geodetic data sets (e.g. inSAR - Meyer et al, 1996, GPS - Clarke et al., 1997) and has led to conflicting subsurface fault interpretations. In order to better model the subsurface fault geometry we …


Metafam: A Unified Classification Of Protein Families I. Overview And Statistics, Elizabeth Shoop, K. Silverstein, Et Al Dec 2000

Metafam: A Unified Classification Of Protein Families I. Overview And Statistics, Elizabeth Shoop, K. Silverstein, Et Al

Elizabeth Shoop

No abstract provided.


Determination Of The Quadratic Slope Parameter In Eta -> 3 Pi(0) Decay, Wb Tippens, S Prakhov, Ce Allgower, V Bekrenev, E Berger, Wj Briscoe, M Clajus, Jr Comfort, K Craig, A Efendiev, D Grosnick, Br Holstein, Gm Huber, D Isenhower, N Knecht, D Koetke, A Koulbardis, N Kozlenko, S Kruglov, Gj Lolos, I Lopatin, Dm Manley, A Marusic, R Manweiler, S Mcdonald, Bmk Nefkens, J Olmsted, Z Papandreou, N Phaisangittisakul, Jw Price, M Pulver, Af Ramirez, Me Sadler, A Shafi, H Spinka, S Stanislaus, A Starostin, Hm Staudenmaier Dec 2000

Determination Of The Quadratic Slope Parameter In Eta -> 3 Pi(0) Decay, Wb Tippens, S Prakhov, Ce Allgower, V Bekrenev, E Berger, Wj Briscoe, M Clajus, Jr Comfort, K Craig, A Efendiev, D Grosnick, Br Holstein, Gm Huber, D Isenhower, N Knecht, D Koetke, A Koulbardis, N Kozlenko, S Kruglov, Gj Lolos, I Lopatin, Dm Manley, A Marusic, R Manweiler, S Mcdonald, Bmk Nefkens, J Olmsted, Z Papandreou, N Phaisangittisakul, Jw Price, M Pulver, Af Ramirez, Me Sadler, A Shafi, H Spinka, S Stanislaus, A Starostin, Hm Staudenmaier

Barry R Holstein

We have determined the quadratic slope parameter α for η→3π0 to be α = -0.031(4) from a 99% pure sample of 106η→3π0 decays produced in the reaction π-p→nη close to the η threshold using the Crystal Ball detector at the AGS. The result is four times more precise than the present world data and disagrees with current chiral perturbation theory calculations by about four standard deviations.


Biorthogonal Wavelets With Certain Regularities, Tian-Xiao He Dec 2000

Biorthogonal Wavelets With Certain Regularities, Tian-Xiao He

Tian-Xiao He

No abstract provided.


The Metafam Server: A Comprehensive Protein Family Resource, Elizabeth Shoop, K. Silverstein, Et Al Dec 2000

The Metafam Server: A Comprehensive Protein Family Resource, Elizabeth Shoop, K. Silverstein, Et Al

Elizabeth Shoop

No abstract provided.


Interdependence Of Non-Overlapping Cortical Systems In Dual Cognitive Tasks, Marcel Adam Just, Patricia A. Carpenter, Timothy A. Keller, Lisa Emery, Holly Zajac, Keith R. Thulborn Dec 2000

Interdependence Of Non-Overlapping Cortical Systems In Dual Cognitive Tasks, Marcel Adam Just, Patricia A. Carpenter, Timothy A. Keller, Lisa Emery, Holly Zajac, Keith R. Thulborn

Marcel Adam Just

No abstract provided.


Comment On "A Check Of Prigogine's Theorem Of Minimum Entropy Production In A Rod In A Nonequilibrium Stationary State", Peter Palffy-Muhoray Dec 2000

Comment On "A Check Of Prigogine's Theorem Of Minimum Entropy Production In A Rod In A Nonequilibrium Stationary State", Peter Palffy-Muhoray

Peter Palffy-Muhoray

No abstract provided.


Oral History Interview With Edsger W. Dijkstra, Philip L. Frana Dec 2000

Oral History Interview With Edsger W. Dijkstra, Philip L. Frana

Philip L Frana

In this oral history Edsger Dijkstra recounts his early education and training as a theoretical physicist and as a'programmer'. Dijkstra describes his work developing software, and his activities at several early information processing conferences. Dijkstra also discourses on the development of ALGOL 60 and the origins of computing science in Europe and America.


A Binary Entropy Measure To Assess Nonrigid Registration Algorithms, Simon K. Warfield, Jan Rexilius, Petra S. Huppi, Terrie E. Inder, Erik G. Learned-Miller, William M. Wells Iii, Gary P. Zientara, Ferenc A. Jolesz, Ron Kikinis Dec 2000

A Binary Entropy Measure To Assess Nonrigid Registration Algorithms, Simon K. Warfield, Jan Rexilius, Petra S. Huppi, Terrie E. Inder, Erik G. Learned-Miller, William M. Wells Iii, Gary P. Zientara, Ferenc A. Jolesz, Ron Kikinis

Erik G Learned-Miller

Assessment of normal and abnormal anatomical variability requires a coordinate system enabling inter-subject comparison. We present a binary minimum entropy criterion to assess affine and nonrigid transformations bringing a group of subject scans into alignment. This measure is a data-driven measure allowing the identification of an intrinsic coordinate system of a particular group of subjects. We assessed two statistical atlases derived from magnetic resonance imaging of newborn infants with gestational age ranging from 24 to 40 weeks. Over this age range major structural changes occur in the human brain and existing atlases are inadequate to capture the resulting anatomical variability. …


Color Eigenflows : Statistical Modeling Of Joint Color Changes, Erik G. Learned-Miller, Kinh Tieu Dec 2000

Color Eigenflows : Statistical Modeling Of Joint Color Changes, Erik G. Learned-Miller, Kinh Tieu

Erik G Learned-Miller

We develop a linear model of commonly observed joint color changes in images due to variation in lighting and certain non-geometric camera parameters. This is done by observing how all of the colors are mapped between two images of the same scene under various “real-world” lighting changes. We represent each instance of such a joint color mapping as a 3-D vector field in RGB color space. We show that the variance in these maps is well represented by a low dimensional linear subspace of these vector fields. We dub the principal components of this space the color eigenflows. When applied …


An Intrinsic Coordinate System Of The Developing Human Brain, Simon K. Warfield, Petra S. Huppi, Terrie E. Inder, Erik G. Learned-Miller, William M. Wells Iii, Gary P. Zientara, Ferenc A. Jolesz, Ron Kikinis Dec 2000

An Intrinsic Coordinate System Of The Developing Human Brain, Simon K. Warfield, Petra S. Huppi, Terrie E. Inder, Erik G. Learned-Miller, William M. Wells Iii, Gary P. Zientara, Ferenc A. Jolesz, Ron Kikinis

Erik G Learned-Miller

No abstract provided.


Biorthogonal Wavelets With Certain Regularities, Tian-Xiao He Dec 2000

Biorthogonal Wavelets With Certain Regularities, Tian-Xiao He

Tian-Xiao He

No abstract provided.


Lead Isotope Tracking Of Atmospheric Response To Post- Industrial Conditions In Yerevan, Armenia, Charles Dunlap, Robert Kurkjian Dec 2000

Lead Isotope Tracking Of Atmospheric Response To Post- Industrial Conditions In Yerevan, Armenia, Charles Dunlap, Robert Kurkjian

Charles Dunlap

Temporal gradients in environmental lead concentrations and isotopic compositions trace the rapidly shifting transition from high to low industrial emissions in Yerevan, Armenia following the dissolution of the Soviet Union in the early 1990s. Shortly after the breakup, in 1995 and 1996, atmospheric lead concentrations averaged ~0.4 µg/m3 and the combustion of leaded gasoline was the primary source of industrial lead emissions in Yerevan. But by 1998, unleaded gasoline was predominant and atmospheric lead concentrations had decreased by two orders of magnitude to ≤ 0.003 µg/m3 because industrial lead emissions from stationary sources had also been radically curtailed. The increased …


A Service Paradigm For Reconfigurable Agents, Gary Holness, Deepak Karuppiah, Subramanya Uppala, Roderic Grupen, S. Chandu Ravela Dec 2000

A Service Paradigm For Reconfigurable Agents, Gary Holness, Deepak Karuppiah, Subramanya Uppala, Roderic Grupen, S. Chandu Ravela

Roderic Grupen

Applications of multiple processors embedded in the systems involved with entertainment, informatics, climate control, communication, transportation, and food preparation are already commonplace. A network of these embedded processors presents application development challenges since the state space grows exponentially as new devices attach to the network. The programming model for such systems will need to change if reliable systems are to be realized. By observing information about sensorimotor activity, such systems can gather information useful to programming the network. Through such interaction, a network can build hierarchies of shareable computational structures for representing various activities. This application domain presents additional challenges …


Lighting Invariance Through Joint Color Change Models, Erik G. Learned-Miller, Kinh Tieu, Eric Grimson Dec 2000

Lighting Invariance Through Joint Color Change Models, Erik G. Learned-Miller, Kinh Tieu, Eric Grimson

Erik G Learned-Miller

In [9], we introduced a linear statistical model of joint color changes in images due to variation in lighting and certain non-geometric camera parameters. We did this by measuring the mappings of colors in one image of a scene to colors in another image of the same scene under different lighting conditions. In this paper, we extend our model in several ways and examine its applicability to several important problems in machine vision. The extensions to our model include incorporating a model of image noise and a prior on the color flows used to explain a particular image difference. In …


The Neural Bases Of Sentence Comprehension: A Fmri Examination Of Syntactic And Lexical Processing, Timothy A. Keller, Patricia A. Carpenter, Marcel Adam Just Dec 2000

The Neural Bases Of Sentence Comprehension: A Fmri Examination Of Syntactic And Lexical Processing, Timothy A. Keller, Patricia A. Carpenter, Marcel Adam Just

Marcel Adam Just

No abstract provided.


An Fmri Investigation Of Sentence Comprehension By Eye And By Ear: Modality Fingerprints On Cognitive Processes, Erica B. Michael, Timothy A. Keller, Patricia A. Carpenter, Marcel Adam Just Dec 2000

An Fmri Investigation Of Sentence Comprehension By Eye And By Ear: Modality Fingerprints On Cognitive Processes, Erica B. Michael, Timothy A. Keller, Patricia A. Carpenter, Marcel Adam Just

Marcel Adam Just

No abstract provided.


The Discovery-Oriented Approach To Organic Chemistry. 5. Stereochemistry Of E2 Elimination: Elimination Of Cis- And Trans-2-Methylcyclohexyl Tosylate, Ram S. Mohan, Marcus E. Cabay, Brad J. Ettlie, Adam J. Tuite, Kurt A. Welday Dec 2000

The Discovery-Oriented Approach To Organic Chemistry. 5. Stereochemistry Of E2 Elimination: Elimination Of Cis- And Trans-2-Methylcyclohexyl Tosylate, Ram S. Mohan, Marcus E. Cabay, Brad J. Ettlie, Adam J. Tuite, Kurt A. Welday

Ram S. Mohan

The E2 elimination is one of the most important reactions in organic chemistry and is discussed in considerable detail in a sophomore organic course. We have developed a discovery-oriented lab that illustrates the stereochemistry of the E2 elimination reaction and is a good exercise in 1H NMR spectroscopy. The added element of discovery insures that student interest and enthusiasm are retained.


Deprotection Of Ketoximes Using Bismuth(Iii) Nitrate Pentahydrate, Ram S. Mohan, Bryce A. Nattier, Kyle J. Eash Dec 2000

Deprotection Of Ketoximes Using Bismuth(Iii) Nitrate Pentahydrate, Ram S. Mohan, Bryce A. Nattier, Kyle J. Eash

Ram S. Mohan

Ketoximes undergo facile deprotection in acetone-H20 (9: 1) in the presence 01' 0.5 equivalents of Bi(N03h•5H20. Bismuth(III) nitrate is relatively non-toxic, insensitive to air and inexpensive. These features coupled with the use of a relatively nontoxic solvent system make this method an attractive alternative to existing routes for deprotection of ketoximes.


The Discovery-Oriented Approach To Organic Chemistry. 4. Epoxidation Of P-Methoxy-Trans-Β-Methylstyrene. An Exercise In 1H Nmr And 13C Nmr Spectroscopy For Sophomore Organic Laboratories, Ram S. Mohan, Rebecca S. Centko Dec 2000

The Discovery-Oriented Approach To Organic Chemistry. 4. Epoxidation Of P-Methoxy-Trans-Β-Methylstyrene. An Exercise In 1H Nmr And 13C Nmr Spectroscopy For Sophomore Organic Laboratories, Ram S. Mohan, Rebecca S. Centko

Ram S. Mohan

Epoxidation of alkenes using peroxyacids is one of the most fundamental reactions in organic chemistry, yet there are very few examples of laboratory experiments that illustrate this important reaction. We have developed a discovery-oriented lab experiment that illustrates epoxidation of alkenes as well as the reactivity of epoxides toward acids. The experiment involves reaction of p-methoxy-trans-β-methylstyrene (trans-anethole) with m-chloroperoxybenzoic acid (MCPBA), in both the absence and presence of a buffer, followed by product identification using 1H NMR, 13C NMR, and IR spectroscopy. The added element of discovery ensures that students' interest and enthusiasm are retained.


A Facile And Efficient Method For The Rearrangement Of Aryl-Substituted Epoxides To Aldehydes And Ketones Using Bismuth Triflate, Ram S. Mohan, Kaushik A. Bhatia, Kyle J. Eash, Nicholas M. Leonard, Matthew C. Oswald Dec 2000

A Facile And Efficient Method For The Rearrangement Of Aryl-Substituted Epoxides To Aldehydes And Ketones Using Bismuth Triflate, Ram S. Mohan, Kaushik A. Bhatia, Kyle J. Eash, Nicholas M. Leonard, Matthew C. Oswald

Ram S. Mohan

Aryl-substituted epoxides undergo smooth rearrangement in the presence of 0.01–0.1 mol% Bi(OTf)3•xH2O. The rearrangement is regioselective with aryl-substituted epoxides, and products arise from cleavage of the benzylic C―O bond. The highly catalytic nature of this method coupled with the fact that the reagent is relatively non-toxic, easy to handle and inexpensive make it an attractive alternative to more corrosive and toxic Lewis acids, such as BF3•Et2O, currently used to effect epoxide rearrangements.


An Efficient Method For The Chemoselective Synthesis Of Acylals From Aromatic Aldehydes Using Bismuth Triflate, Ram S. Mohan, Marc D. Carrigan, Kyle J. Eash, Matthew C. Oswald Dec 2000

An Efficient Method For The Chemoselective Synthesis Of Acylals From Aromatic Aldehydes Using Bismuth Triflate, Ram S. Mohan, Marc D. Carrigan, Kyle J. Eash, Matthew C. Oswald

Ram S. Mohan

Aromatic aldehydes are smoothly converted into the corresponding acylals in good yields in the presence of 0.10 mol% Bi(OTf)3•xH2O. Ketones are not affected under the reaction conditions. The highly catalytic nature of bismuth triflate and the fact that it is relatively non-toxic, easy to handle and insensitive to small amounts of air and moisture makes this procedure especially attractive for large-scale synthesis.


Modeling Score Distributions For Combining The Outputs Of Search Engines, R. Manmatha, T. Rath, F. Feng Dec 2000

Modeling Score Distributions For Combining The Outputs Of Search Engines, R. Manmatha, T. Rath, F. Feng

R. Manmatha

In this paper the score distributions of a number of text search engines are modeled. It is shown empirically that the score distributions on a per query basis may be fitted using an exponential distribution for the set of non-relevant documents and a normal distribution for the set of relevant documents. Experiments show that this model fits TREC-3 and TREC-4 data for not only probabilistic search engines like INQUERY but also vector space search engines like SMART for English. We have also used this model to fit the output of other search engines like LSI search engines and search engines …


An Empirical Model Of Amino Acid Transformations In An Alpine Soil, David A. Lipson, Ted K. Raab, Steven K. Schmidt, Russ K. Monson Dec 2000

An Empirical Model Of Amino Acid Transformations In An Alpine Soil, David A. Lipson, Ted K. Raab, Steven K. Schmidt, Russ K. Monson

Ted K. Raab

Amino acids are potentially important nitrogen (N) sources for plants in many ecosystems. However, a quantitative understanding of organic N availability is lacking for most ecosystems. This study estimates seasonal amino acid fluxes in an alpine tundra soil using three independent data sets. In previous work in an alpine dry meadow ecosystem in the Front Range of the Colorado Rocky Mountains, we measured signifcant rates of amino acid production from soil peptides during the plant growing season. This suggested that proteolysis of native soil peptides could serve as a measure of amino acid availability to plants. Here we use a …


An Investigation Of Environmental Racism Claims: Testing Environmental Management Approaches With A Geographic Information System, Gregg P. Macey Dec 2000

An Investigation Of Environmental Racism Claims: Testing Environmental Management Approaches With A Geographic Information System, Gregg P. Macey

Gregg P. Macey

The purpose of this research was to explore the concept of an environmental racism claim through the use of several environmental management tools. The EPA's Toxics Release Inventory, Cumulative Exposure Project, and the Los Angeles County Department of Health Services' Hot Zone Census Tract Assessment were combined with racial and socioeconomic data to test claims that minorities in South Central Los Angeles are disproportionately exposed to environmental lead. Multivariate analysis indicated that race is strongly associated with the number of cases of elevated lead levels in South Central, irrespective of poverty status. Proximity to point sources, a common focal point …


Optically Induced Periodic Structures In Smectic-C Liquid Crystals, Antal Jákli, A. Vajda, E. Benkler, Janossy, Peter Palffy-Muhoray Dec 2000

Optically Induced Periodic Structures In Smectic-C Liquid Crystals, Antal Jákli, A. Vajda, E. Benkler, Janossy, Peter Palffy-Muhoray

Peter Palffy-Muhoray

We explore periodic structures of smectic-C (SmC) liquid crystals, induced optically by a polarization grating. The studied cells contain a passive surface of rubbed polyimide and an active photosensitive substrate of ate-dye doped polyimide. In a nematic phase the director field can be periodic independent of the angle between the grating vector and the rubbing direction. In the SmA phase periodic structure can be induced only by layer undulations. The SmC behaves similarly to the nematic phase, but the director can rotate only on a cone, which results in a more complex geometry. The periodic pattern is superimposed with four …


Teacher’S Stages Of Development In Using Visualization Tools For Inquiry-Based Science: The Case Of Project Vism, M. Charles, Robert A. Kolvoord Dec 2000

Teacher’S Stages Of Development In Using Visualization Tools For Inquiry-Based Science: The Case Of Project Vism, M. Charles, Robert A. Kolvoord

Robert A Kolvoord

No abstract provided.


Learning Object-Independent Modes Of Variation With Feature Flow Fields, Erik G. Learned-Miller, Kinh Tieu, Chris Stauffer Dec 2000

Learning Object-Independent Modes Of Variation With Feature Flow Fields, Erik G. Learned-Miller, Kinh Tieu, Chris Stauffer

Erik G Learned-Miller

We present a unifying framework in which object-independent modes of variation are learned from continuous-time data such as video sequences. These modes of variation can be used as generators to produce a manifold of images of a new object from a single example of that object. We develop the framework in the context of a well-known example: analyzing the modes of spatial deformations of a scene under camera movement. Our method learns a close approximation to the standard affine deformations that are expected from the geometry of the situation, and does so in a completely unsupervised (i.e. ignorant of the …


Karst Genetic Model For The French Bay Breccia Deposits, San Salvador, Bahamas, Lee J. Florea, John Mylroie, Jim Carew Dec 2000

Karst Genetic Model For The French Bay Breccia Deposits, San Salvador, Bahamas, Lee J. Florea, John Mylroie, Jim Carew

Lee J Florea, PhD, P.G.

No abstract provided.