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2001

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Articles 1891 - 1920 of 3030

Full-Text Articles in Physical Sciences and Mathematics

Perspectives Of Giant Magnetoresistance, Evgeny Y. Tsymbal, David G. Pettifor Jan 2001

Perspectives Of Giant Magnetoresistance, Evgeny Y. Tsymbal, David G. Pettifor

Evgeny Tsymbal Publications

Giant magnetoresistance (GMR) is one of the most fascinating discoveries in thin-film magnetism, which combines both tremendous technological potential and deep fundamental physics. Within a decade of GMR being discovered in 1988 commercial devices based on this phenomenon, such as hard-disk read-heads, magnetic field sensors and magnetic memory chips, had become available in the market. These achievements would not have been possible without a detailed understanding of the physics of GMR, which requires a quantum-mechanical insight into the electronic spin-dependent transport in magnetic structures.


Species And Ecosystem Conservation: An Interdisciplinary Approach, Tim W. Clark, Michael J. Stevenson, Kim Ziegelmayer Jan 2001

Species And Ecosystem Conservation: An Interdisciplinary Approach, Tim W. Clark, Michael J. Stevenson, Kim Ziegelmayer

Yale School of the Environment Bulletin Series

No abstract provided.


The Atlantic Sea Scallop Fishery In The U.S.And Canada: A Natural Experiment In Fisheries Management Regimes, Robert Repetto Jan 2001

The Atlantic Sea Scallop Fishery In The U.S.And Canada: A Natural Experiment In Fisheries Management Regimes, Robert Repetto

Yale School of the Environment Publications Series

The Atlantic sea scallop fisheries in the U.S. and Canadian offshore waters provide a natural experiment in fisheries management regimes. Starting in 1986, in side by side areas of George’s Bank, Canada adopted a rights-based approach while the U.S. continued with effort controls. Analysis of their experiences shows that the resource has been better maintained in Canada with lower fishing effort, that the Canadian fishing industry has become more prosperous and innovative relative to that in the U.S., and that the Canadian co-management regime is more cooperative. These results suggest that systematic evaluation of actual experience with rights-based fishery management …


Extended Powers Of Manifolds And The Adams Spectral Sequence, Robert R. Bruner Jan 2001

Extended Powers Of Manifolds And The Adams Spectral Sequence, Robert R. Bruner

Mathematics Faculty Research Publications

The extended power construction can be used to create new framed manifolds out of old. We show here how to compute the effect of such operations in the Adams spectral sequence, extending partial results of Milgram and the author. This gives the simplest method of proving that Jones’ 30-manifold has Kervaire invariant one, and allows the construction of manifolds representing Mahowald’s classes η4 and η5, among others.


Properties Of Some Generalizations Of Kac-Murdock-Szeg"O Matrices, William Trench Jan 2001

Properties Of Some Generalizations Of Kac-Murdock-Szeg"O Matrices, William Trench

William F. Trench

No abstract provided.


Interfering Solutions Of A Nonhomogeneous Hamiltonian System, Gregory S. Spradlin Jan 2001

Interfering Solutions Of A Nonhomogeneous Hamiltonian System, Gregory S. Spradlin

Greg S. Spradlin Ph.D.

A Hamiltonian system is studied which has a term approaching a constant at an exponential rate at infinity. A minimax argument is used to show that the equation has a positive homoclinic solution. The proof employs the interaction between translated solutions of the corresponding homogeneous equation. What distinguishes this result from its few predecessors is that the equation has a nonhomogeneous nonlinearity.


The Relative Performance Of Full Information Maximum Likelihood Estimation For Missing Data In Structural Equation Models, C. K. Enders, Deborah L. Bandalos Jan 2001

The Relative Performance Of Full Information Maximum Likelihood Estimation For Missing Data In Structural Equation Models, C. K. Enders, Deborah L. Bandalos

Deborah L Bandalos

No abstract provided.


N-Methyl-D-Aspartate Channel And Consciousness: From Signal Coincidence Detection To Quantum Computing, Armando F. Rocha, Alfredo Pereira Jr Jan 2001

N-Methyl-D-Aspartate Channel And Consciousness: From Signal Coincidence Detection To Quantum Computing, Armando F. Rocha, Alfredo Pereira Jr

Armando F Rocha

Research on Blindsight, Neglect/Extinction and Phantom limb syndromes, as well as electrical measurements of mammalian brain activity, have suggested the dependence of vivid perception on both incoming sensory information at primary sensory cortex and reentrant information from associative cortex. Coherence between incoming and reentrant signals seems to be a necessary condition for (conscious) perception. General reticular activating system and local electrical synchronization are some of the tools used by the brain to establish coarse coherence at the sensory cortex, upon which biochemical processes are coordinated. Besides electrical synchrony and chemical modulation at the synapse, a central mechanism supporting such a …


Numerical Solution Of Fuzzy Differential Equation By Runge-Kutta Method, S. Abbasbandy, T. Allah Viranloo Jan 2001

Numerical Solution Of Fuzzy Differential Equation By Runge-Kutta Method, S. Abbasbandy, T. Allah Viranloo

Saeid Abbasbandy

In this paper numerical algorithms for solving 'fuzzy ordinary differential equations' are considered. A scheme based on the 4th Runge-Kutta method in detail is discussed and this is followed by a complete error analysis. The algorithm is illustrated by solving some linear and nonlinear fuzzy Cauchy problems.


Numerical Solution Of Fuzzy Differential Equation By Runge-Kutta Method Of Order 2, S. Abbasbandy, T. Allah Viranloo Jan 2001

Numerical Solution Of Fuzzy Differential Equation By Runge-Kutta Method Of Order 2, S. Abbasbandy, T. Allah Viranloo

Saeid Abbasbandy

In this paper numerical algorithms for solving 'fuzzy ordinary differential equations' are considered. A scheme on the 2nd Rung-Kutta method in detail is discussed and this is followed by a complete error analysis. The algorithm is illustrated by solving some linear and nonlinear fuzzy Cauchy problems.


Joachim Castella: Studien Zur Thematik "Kalkül Und Kreativität", Rudolf Kaehr Jan 2001

Joachim Castella: Studien Zur Thematik "Kalkül Und Kreativität", Rudolf Kaehr

Rudolf Kaehr

Utopie der Zeichen – Zeichen der Utopie Vilém Flusser und Gotthard Günther als Komplement einer neuen Medienphilosophie Medientheorie als Theoriemedium Prolegomena einer allgemeinenMedientheorie Philosophie des LMR Joachim Castella 2000/2001


Significance Of The Sagnac Effect, Pal R. Molnar Jan 2001

Significance Of The Sagnac Effect, Pal R. Molnar

Pal R. Molnar

During the historical development, the notions of electrodynamics and the theory light have become complicated complexes of concepts [1]. And what is more, nowadays they are wholly confused. The laws of electrodynamics in present form are not valid in rotating and deforming systems [2]. These turbulent notion-complexes -of which inadequacy to the inner connections are verified by experiments, measurements results, as well as certain electrodynamical states and processes- have to be broken open, disintegrated, then disjoined. Henceforth, we must search those genuine, pure and simple electrodynamical ideas, which can already join in the immanent natural well and adequate manner. Consequently, …


On The Uniform Convergence Of Walsh-Fourier Series, Ushangi Goginava Jan 2001

On The Uniform Convergence Of Walsh-Fourier Series, Ushangi Goginava

Ushangi Goginava

No abstract provided.


Probabilities Of Transition Among Health States For Older Adults, Paula Diehr Jan 2001

Probabilities Of Transition Among Health States For Older Adults, Paula Diehr

Paula Diehr

GOAL: To estimate the probabilities of transition among self-rated health states for older adults, and examine how they vary by age and sex. METHODS: We used self-rated health (excellent, very good, good, fair, poor, dead) collected in two longitudinal studies of older adults (mean age 75) to estimate the probability of transition in 2 years. We used the estimates to project future health for selected cohorts. FINDINGS: These older adults were most likely to be in the same health state 2 years later, but a substantial proportion changed in both directions. Transition probabilities varied by initial health state, age and …


Patterns Of Self-Rated Health In Older Adults Before And After Sentinel Events, Paula Diehr Jan 2001

Patterns Of Self-Rated Health In Older Adults Before And After Sentinel Events, Paula Diehr

Paula Diehr

OBJECTIVES: To describe and compare patterns of change in self-rated health for older adults before death and before and after stroke, myocardial infarction, congestive heart failure, cardiac procedure, hospital admission for cancer, and hip fracture. DESIGN: "Event cohort," measuring time in months before and after the event. SETTING: Four U.S. communities. PARTICIPANTS: 5888 participants in the Cardiovascular Health Study (CHS), sampled from Medicare rolls and followed up to 8 years. Mean age at baseline was 73. MEASUREMENTS: Self-rated health, including a category for death, assessed at 6-month intervals, and ascertainment of events. METHODS: We examined the percentage that was healthy …


Testing For Asymmetry In Economic Time Series Using Bootstrap Methods, Claudio Lupi, Patrizia Ordine Jan 2001

Testing For Asymmetry In Economic Time Series Using Bootstrap Methods, Claudio Lupi, Patrizia Ordine

Claudio Lupi

In this paper we show that phase-scrambling bootstrap offers a natural framework for asymmetry testing in economic time series. A comparison with other bootstrap schemes is also sketched. A Monte Carlo analysis is carried out to evaluate the size and power properties of the phase-scrambling bootstrap-based test.


Mathematical Aspects Of Oriental Carpets, Carol Bier Jan 2001

Mathematical Aspects Of Oriental Carpets, Carol Bier

Carol Bier

The mathematical principles of pattern making according to symmetrical repetition are well-known today, but the mathematical aspects of pattern formation have been glossed over in the study of Oriental carpets, or neglected in favor of either an appreciation of color and form or a discussion of social and ethnic origins. This article seeks to address several mathematical aspects of Oriental carpets, which are both integral to their form and manifest in their visual make-up.


Benchmarking Patient Outcomes, Ellen B. Rudy, Joseph F. Lucke, Gayle R. Whitman, Lynda J. Davidson Jan 2001

Benchmarking Patient Outcomes, Ellen B. Rudy, Joseph F. Lucke, Gayle R. Whitman, Lynda J. Davidson

Joseph Lucke

Purpose: To examine the usefulness of three types of benchmarking for interpreting patient outcome data.

Design: This study was part of a multiyear, multihospital longitudinal survey of 10 patient outcomes. The patient outcome used for this methodologic presentation was central line infections (CLI). The sample included eight hospitals in an integrated healthcare system, with a range in size from 144 to 861 beds. The unit of analysis for CLI was the number of line days, with the CLI rate defined as the number of infections per 1,000 patient-line days per month.

Methods: Data on each outcome were collected at the …


Spatially Correlated Dynamics In A Simulated Glass-Forming Polymer Melt: Analysis Of Clustering Phenomena, Y. Gebremichael, T. B. Schroder, Francis W. Starr, S. C. Glotzer Jan 2001

Spatially Correlated Dynamics In A Simulated Glass-Forming Polymer Melt: Analysis Of Clustering Phenomena, Y. Gebremichael, T. B. Schroder, Francis W. Starr, S. C. Glotzer

Francis Starr

No abstract provided.


Effects Of A Nanoscopic Filler On The Structure And Dynamics Of A Simulated Polymer Melt And The Relationship To Ultra-Thin Films, Francis W. Starr, T. B. Schroder, S. C. Glotzer Jan 2001

Effects Of A Nanoscopic Filler On The Structure And Dynamics Of A Simulated Polymer Melt And The Relationship To Ultra-Thin Films, Francis W. Starr, T. B. Schroder, S. C. Glotzer

Francis Starr

No abstract provided.


Static And Dynamic Properties Of Stretched Water, P. A. Netz, Francis W. Starr, H. E. Stanley, M. C. Barbosa Jan 2001

Static And Dynamic Properties Of Stretched Water, P. A. Netz, Francis W. Starr, H. E. Stanley, M. C. Barbosa

Francis Starr

No abstract provided.


Dynamics Of Supercooled Water In Configuration Space, Emilia La Nave, Antonio Scala, Francis W. Starr, Francesco Sciortino, H. Eugene Stanley Jan 2001

Dynamics Of Supercooled Water In Configuration Space, Emilia La Nave, Antonio Scala, Francis W. Starr, Francesco Sciortino, H. Eugene Stanley

Francis Starr

No abstract provided.


Thermodynamic And Structural Aspects Of The Potential Energy Surface Of Simulated Water, Francis W. Starr, S. Sastry, E. La Nave, A. Scala, H. E. Stanley, F. Sciortino Jan 2001

Thermodynamic And Structural Aspects Of The Potential Energy Surface Of Simulated Water, Francis W. Starr, S. Sastry, E. La Nave, A. Scala, H. E. Stanley, F. Sciortino

Francis Starr

No abstract provided.


Mixture Hazards Models With Additive Random Effects Accounting For Treatment Effectiveness Lag Time, Ying Qing Chen, C. A. Rohde, M.-C. Wang Jan 2001

Mixture Hazards Models With Additive Random Effects Accounting For Treatment Effectiveness Lag Time, Ying Qing Chen, C. A. Rohde, M.-C. Wang

U.C. Berkeley Division of Biostatistics Working Paper Series

In many clinical trials to evaluate treatment efficacy, it is believed that there may exist latent treatment effectiveness lag times after which medical treatment procedure or chemical compound would be in full effect. In this article, semiparametric regression models are proposed and studied for estimating the treatment effect accounting for such latent lag times. The new models take advantage of the invariance property of the additive hazards model in marginalising over an additive latent variable; parameters in the models are thus easily estimated and interpreted, while the flexibility of not having to specify the baseline hazard function is preserved. Monte …


Phylogeographic Analysis Of The Threatened And Endangered Superconglutinate-Producing Mussels Of The Genus Lampsilis (Bivalvia: Unionidae), Kevin J. Roe, Charles Lydeard, Paul D. Hartfield Jan 2001

Phylogeographic Analysis Of The Threatened And Endangered Superconglutinate-Producing Mussels Of The Genus Lampsilis (Bivalvia: Unionidae), Kevin J. Roe, Charles Lydeard, Paul D. Hartfield

Kevin J. Roe

Several species of freshwater unionid mussels in the genus Lampsilis exhibit a remarkable reproductive strategy. Female mussels of these species enclose their larvae in a minnow-like lure, called a ‘superconglutinate’, to attract piscivorous fishes. When a fish attempts to ingest the superconglutinate the lure ruptures and the larvae are released to parasitize the fish. Of the four species of mussel which exhibit this strategy and are endemic to the Gulf Coast drainages of the southeastern United States, three are protected under the Endangered Species Act, and one is recognized as imperilled. Phylogenetic analysis of nucleotide sequences of the mitochondrial 16S …


Long Recurrence Records From The Wasatch Fault Zone, Utah, James P. Mccalpin Jan 2001

Long Recurrence Records From The Wasatch Fault Zone, Utah, James P. Mccalpin

James P. McCalpin

The Wasatch fault "megatrench" was excavated in September 1999 across two fault scarps totaling 18 meters high on the Salt Lake City segment of the Wasatch fault zone (WFZ). The purpose of the megatrench was to date a long series of consecutive earthquakes (8-12 events?) on the WFZ and measure the variability of recurrence times between the events.This variability could then be used in calculating the future probability of large earthquakes on the WFZ. The trench was located 1 km north of the mouth of Little Cottonwood Canyon, at an elevation of 1525 m, between the Bonneville highstand (ca. 17.5 …


Paleoseismicity Of Quaternary Faults Near Albuquerque, New Mexico: The Zia Fault, James P. Mccalpin Jan 2001

Paleoseismicity Of Quaternary Faults Near Albuquerque, New Mexico: The Zia Fault, James P. Mccalpin

James P. McCalpin

This study continues USGS-funded efforts to assess the activity and earthquake hazard potential of Quaternary faults in the Albuquerque metropolitan region. Our target in 2000 was the Zia fault, a 37 km-long normal fault that trends N-S in northern Llano de Albuquerque (LdA). The Zia fault is one of three major east-dipping normal faults that define the western margin of the Rio Grande rift in the northern Albuquerque basin, the other faults being the Calabacillas fault (to the west of the Zia fault) and the County Dump fault (to the east of the Zia fault) (Machette et al., 1998). In …


Dispersion Of Potassium Nitrate And The Resulting Strong Basicity On Zirconia, Ying Wang, Wenyu Huang, Yuan Chun, Jia Rong Xia, Jian Hua Zhu Jan 2001

Dispersion Of Potassium Nitrate And The Resulting Strong Basicity On Zirconia, Ying Wang, Wenyu Huang, Yuan Chun, Jia Rong Xia, Jian Hua Zhu

Wenyu Huang

A novel solid superbase is derived from zirconia-supported potassium nitrate. Dispersion and decomposition of potassium nitrate on zirconia were investigated and compared with that on alumina to explore the effect of the support on the preparation of solid strong bases. Spontaneous dispersion capacity of KNO3 on ZrO2 was found to be 8.1 K+ nm-2, very close to that of a vacant site on ZrO2. An unusually strong basicity was generated on ZrO2 through decomposition of the loaded KNO3 that began around 613 K, enhancing the catalytic activity of ZrO2 in cis-but-2-ene isomerization at 273 K. Moreover, KNO3/ZrO2 samples, except 34% …


Higher Twist Corrections And Maxima For Dis On A Proton In The High Density Qcd Region, E. Gotsman, Eugene Levin, U. Maor, L. Mclerran, Kirill Tuchin Jan 2001

Higher Twist Corrections And Maxima For Dis On A Proton In The High Density Qcd Region, E. Gotsman, Eugene Levin, U. Maor, L. Mclerran, Kirill Tuchin

Kirill Tuchin

We show that the ratio of different structure functions have a maximum which depends on energy. We argue, using the Golec-Biernat and Wusthoff model as well as the eikonal approach, that these maxima are functions of the saturation scale. We analyze leading and higher twist contributions for different observables to check whether a kinematic region exists where high parton density effects can be detected experimentally.


Synthesis And Characterization Of Potassium-Modified Alumina Superbases, Ying Wang, Jian Hua Zhu, Wenyu Huang Jan 2001

Synthesis And Characterization Of Potassium-Modified Alumina Superbases, Ying Wang, Jian Hua Zhu, Wenyu Huang

Wenyu Huang

Novel solid superbases can be prepared by dispersing potassium salts such as K2CO3 and KHCO3 on alumina followed by thermal treatments. The resulting materials show an extremely high activity in the isomerization of cis-but-2-ene at 0°C and possess base strength of at least H− = + 26.5. X-Ray diffraction (XRD) and Raman spectra of K2CO3 or KHCO3 modified alumina reveal the formation of potassium hydroalumina carbonate, which is the precursor of active species. Decomposition of potassium salts on alumina has been studied by use of thermal gravimetric differential thermal analysis (TG-DTA) and temperature programmed decomposition-mass spectrometry (TPDE-MS). Two CO2 evolution …