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Articles 20611 - 20640 of 21971

Full-Text Articles in Physical Sciences and Mathematics

Tectonic Stability Of The San Luis Hills, Northern Rio Grande Rift, Colorado: Evidence From Paleomagnetic Measurements, Laurie Brown, M. P. Golombek Jan 1997

Tectonic Stability Of The San Luis Hills, Northern Rio Grande Rift, Colorado: Evidence From Paleomagnetic Measurements, Laurie Brown, M. P. Golombek

Laurie Brown

The San Luis Basin is the largest of four tilted, fault bounded Neogene basins of the northern Rio Grande rift in New Mexico and Colorado. It formed during the second of two episodes of extension beginning in middle Oligocene and extending to the present. The San Luis Hills are an intrarift horst of Oligocene intermediate and basalt rocks preserved in the middle of the San Luis Basin. Previous paleomagnetic and structural studies in the Espanola Basin to the south indicate counterclockwise rotation of that region during the most recent extension. Paleomagnetic samples from the two exposed formations in the San …

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Assessing Surface–Atmosphere Interactions Using Former Soviet Union Standard Meteorological Network Data. Part Ii: Cloud And Snow Cover Effects, P. Ya Groisman, E. L. Genikhovich, Raymond S. Bradley, B. M. Ilyin Jan 1997

Assessing Surface–Atmosphere Interactions Using Former Soviet Union Standard Meteorological Network Data. Part Ii: Cloud And Snow Cover Effects, P. Ya Groisman, E. L. Genikhovich, Raymond S. Bradley, B. M. Ilyin

Raymond S Bradley

Groisman and Genikhovich developed a method to obtain direct estimates of surface turbulent heat fluxes. The authors now apply it to the territory of the former Soviet Union using the 3-/6-h data of 257 stations for the past several decades to assess the sensitivity of sensible heat flux to cloud and snow cover. This property was quantified for bare soil landscapes over the entire country. During the day, the presence of clouds is associated with low values of sensible heat flux from the surface to the atmosphere. At night (and during the day in winter in high latitudes), the sign …

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Prediction Intervals For Weibull Order Statistics, H K. Hsieh Jan 1997

Prediction Intervals For Weibull Order Statistics, H K. Hsieh

H. K. Hsieh

Using a conditional method, explicit formulae for computing quantiles pertinent to prediction intervals for future Weibull order statistics are developed for two cases: when only previous independent failure data are available, and when both previous independent failure data and early-failure data in current experiment are available. The second case includes the case when only current early-failure data are available. Comparisons of interval widths are made for different estimators of parameters and different ways of forming prediction intervals.

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Sensors For Site-Specific Management, Stuart J. Birrell, J. W. Hummel, K. A. Sudduth Jan 1997

Sensors For Site-Specific Management, Stuart J. Birrell, J. W. Hummel, K. A. Sudduth

Stuart J. Birrell

Site-specific management (SSM, also known as precision farming, precision agriculture, prescription farming, etc.) is a management strategy that seeks to address within-field variability and to optimize inputs such as pesticides and fertilizers on a point-by-point basis within a field. By reducing over-application and under-application of nutrients and pesticides, this strategy has the potential to improve profitability for the producer and also to reduce the threat of groundwater or surface water contamination from agrichemicals. SSM is being adopted by innovative producers across the country. Agricultural equipment manufacturers, farm input suppliers, and a host of other businesses are working along with publicsector …

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Eigenfunction And Harmonic Function Estimates In Domains With Horns And Cusps, Michael Cranston, Yi Li Jan 1997

Eigenfunction And Harmonic Function Estimates In Domains With Horns And Cusps, Michael Cranston, Yi Li

Yi Li

No abstract provided.

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Structural And Dynamical Uncertainties In Modelling Axisymmetric Elliptical Galaxies, Aaron J. Romanowsky, C. S. Kochanek Jan 1997

Structural And Dynamical Uncertainties In Modelling Axisymmetric Elliptical Galaxies, Aaron J. Romanowsky, C. S. Kochanek

Aaron J. Romanowsky

Quantitative dynamical models of galaxies require deprojection of the observed surface brightness to determine the luminosity density of the galaxy. Existing deprojection methods for axisymmetric galaxies assume that a unique deprojection exists for any given inclination, even though the projected density is known to be degenerate to the addition of ‘konus densities’ that are invisible in projection. We develop a deprojection method based on linear regularization that can explore the range of luminosity densities that are statistically consistent with an observed surface brightness distribution. The luminosity density is poorly constrained at modest inclinations (i ≿ 30°), even in the limit …

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Three-Dimensional Direct Simulation Monte Carlo Method For Slider Air Bearings, Alejandro Garcia, W. Huang, D. B. Bogy Jan 1997

Three-Dimensional Direct Simulation Monte Carlo Method For Slider Air Bearings, Alejandro Garcia, W. Huang, D. B. Bogy

Alejandro Garcia

The direct simulation Monte Carlo (DSMC) method is used to solve the three-dimensional nano-scale gas film lubrication problem between a gas bearing slider and a rotating disk, and this solution is compared to the numerical solution of the compressible Reynolds equations with the slip flow correction based on the linearized Boltzmann equation as presented by Fukui and Kaneko [molecular gas film lubrication (MGL) method] [ASME J. Tribol. 110, 253 (1988)]. In the DSMC method, hundreds of thousands of simulated particles are used and their three velocity components and three spatial coordinates are calculated and recorded by using a hard-sphere collision …

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Anomalous Flow Profile Due To The Curvature Effect On Slip Length, Alejandro Garcia, K. Tibbs, F. Baras Jan 1997

Anomalous Flow Profile Due To The Curvature Effect On Slip Length, Alejandro Garcia, K. Tibbs, F. Baras

Alejandro Garcia

No abstract provided.

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Complexes Between Nascent Polypeptides And Their Molecular Chaperones In The Cytosol Of Mammalian Cells, Daryl K. Eggers, W. J. Welch, W. J. Hansen Jan 1997

Complexes Between Nascent Polypeptides And Their Molecular Chaperones In The Cytosol Of Mammalian Cells, Daryl K. Eggers, W. J. Welch, W. J. Hansen

Daryl K. Eggers

Folding of newly synthesized proteins in vivo is believed to be facilitated by the cooperative interaction of a defined group of proteins known as molecular chaperones. We investigated the direct interaction of chaperones with nascent polypeptides in the cytosol of mammalian cells by multiple methods. A new approach using a polyclonal antibody to puromycin allowed us to tag and capture a population of truncated nascent polypeptides with no bias as to the identity of the bound chaperones. In addition, antibodies that recognize the cytosolic chaperones hsp70, CCT (TRiC), hsp40, p48 (Hip), and hsp90 were compared on the basis of their …

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Photothermal Lens Spectrometry Of Homogeneous Fluids With Incoherent White‐Light Excitationusing A Cylindrical Sample Cell, Agnes Chartier, Stephen E. Bialkowski Jan 1997

Photothermal Lens Spectrometry Of Homogeneous Fluids With Incoherent White‐Light Excitationusing A Cylindrical Sample Cell, Agnes Chartier, Stephen E. Bialkowski

Stephen E. Bialkowski

A model for photothermal lens signal generation in a cylindrical sample cell under constant irradiance excitation is described and tested. The model is developed with and without the assumption that the sample cell does not change temperature over the irradiation time. In both cases, the photothermal lens is predicted to be parabolic in form with a strength that is independent of sample cell radius. The predicted irradiance independence suggests that incoherent illumination can be used to perform photothermal lens spectroscopy in low-volume cells. Experimental evidence is obtained using a Xe arc lamp to perform photothermal lens spectroscopy in a 6 …

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Diffraction Effects In Single‐ And Two‐Laser Photothermal Lens Spectroscopy, Stephen E. Bialkowski, Agnes Chartier Jan 1997

Diffraction Effects In Single‐ And Two‐Laser Photothermal Lens Spectroscopy, Stephen E. Bialkowski, Agnes Chartier

Stephen E. Bialkowski

A simple method for calculating the effects of optical geometry on photothermal lens signals is shown. This method is based on calculating cumulative electric-field phase shifts produced by a series of Gaussian refractive-index perturbations produced by the photothermal effect. Theoretical results are found for both pulsed-laser and continuous Gaussian laser excitation sources and both single- and two-laser apparatuses commonly employed in photothermal lens spectroscopy. The effects of apparatus geometry on the resulting signal are shown. Analytical time-dependent signal results are found for small signals. Analytical pump–probe focus geometry results allow direct optimization for certain conditions. The calculations indicate that the …

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Review Of Mathematica 3.0, Stan Wagon Dec 1996

Review Of Mathematica 3.0, Stan Wagon

Stan Wagon, Retired

No abstract provided.

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Software Reuse: Architecture, Process And Organization For Business Success, Ivar Jacobson, Martin Griss, Patrik Jonsson Dec 1996

Software Reuse: Architecture, Process And Organization For Business Success, Ivar Jacobson, Martin Griss, Patrik Jonsson

Martin L Griss

No abstract provided.

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Constraint Satisfaction Methods For Generating Valid Cuts, John Hooker Dec 1996

Constraint Satisfaction Methods For Generating Valid Cuts, John Hooker

John Hooker

No abstract provided.

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Statistics For Logisticians, Caroline Lubert Dec 1996

Statistics For Logisticians, Caroline Lubert

Caroline P Lubert

No abstract provided.

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A Niobium(V) Complex With Mixed O,S-Donor Ligands. Synthesis, Structure And Properties Of The Anion Tris(2-Mercapto-4-Methylphenolato)Niobate(V), Paul Challen, Diane Peapus, Karen Magnes Dec 1996

A Niobium(V) Complex With Mixed O,S-Donor Ligands. Synthesis, Structure And Properties Of The Anion Tris(2-Mercapto-4-Methylphenolato)Niobate(V), Paul Challen, Diane Peapus, Karen Magnes

Paul R. Challen

Reaction of Nb(OEt)5 with 2-mercapto-4-methylphenol (mmpH2) in the presence of triethylamine gave the mononuclear tris complex (Et3NH)[Nb(mmp)3] which was structurally characterized. The coordination geometry around the niobium is between octahedral and trigonal prismatic, with a twist angle of 41.5°. The mercaptophenolate ligands are arranged around the metal in a “propeller” fashion. (Et3NH)[Nb(mmp)3] was characterized by IR, 1H NMR and UV-vis spectroscopies, and cyclic voltammetry. A reversible reduction wave found at −1.03 V is for reduction to the NbIV complex.

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Effectiveness Of The Protected Area Network In Biodiversity Conservation: A Case-Study Of Meghalaya State, M. Latif Khan, Shaily Menon, Kamaljit Bawa Dec 1996

Effectiveness Of The Protected Area Network In Biodiversity Conservation: A Case-Study Of Meghalaya State, M. Latif Khan, Shaily Menon, Kamaljit Bawa

Shaily Menon

The North-Eastern region of India is significant for biodiversity conservation because of its floristic richness and high levels of endemism. Deforestation levels are high in the region due to anthropogenic pressures. We accessed various literature sources to create a database for Meghalaya state containing information on plant species, habit, altitudinal distribution, endemism, and endangered status. Information on the existing protected area network (type, extent, and altitudinal representation) was added to the database. The database was used to assess the effectiveness of the existing protected area network in conserving the floristic biodiversity of the state. Of a total of 3331 plant …

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Activities Of The Ilo In The Field Of The Environment, Cleopatra Doumbia-Henry Dec 1996

Activities Of The Ilo In The Field Of The Environment, Cleopatra Doumbia-Henry

Cleopatra Doumbia-Henry

No abstract provided.

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Synthesis Of Bulk, Polycrystalline Gallium Nitride At Low Pressures, Alberto Argoitia, John Angus, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash Dec 1996

Synthesis Of Bulk, Polycrystalline Gallium Nitride At Low Pressures, Alberto Argoitia, John Angus, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash

Jeffrey Dyck

Bulk, polycrytalline gallium nitride was crystallized from gallium saturated with nitrogen obtained from a microwave electron cyclotron resonance source. The polycrystalline samples are wurtzitic and n-type. Well-faceted crystals give near-band-edge and yellow band photo-luminescence at both 10K and 300K. The results show that atomic nitrogen is an attractive alternative to high pressure molecular nitrogen for saturation of gallium with nitrogen for synthesis of bulk gallium nitride.

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Computer System For Simulating Physical Processes Using Multiple Integer State Vectors Us:5594671, Hudong Chen, Peter Churchill, Robert Iannucci, Kim Molvig, Gregory Papadopoulos, Stephen Remondi, Christopher Teixeira, Kenneth Traub Dec 1996

Computer System For Simulating Physical Processes Using Multiple Integer State Vectors Us:5594671, Hudong Chen, Peter Churchill, Robert Iannucci, Kim Molvig, Gregory Papadopoulos, Stephen Remondi, Christopher Teixeira, Kenneth Traub

Robert A Iannucci

No abstract provided.

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Essential Laminations In Graph Manifolds, Ramin Naimi, Mark Brittenham, Rachel Roberts Dec 1996

Essential Laminations In Graph Manifolds, Ramin Naimi, Mark Brittenham, Rachel Roberts

Ramin Naimi

No abstract provided.

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Voltammetric Studies Of Mn@C82, Mark Anderson, Harry Dorn, Paul Burbank, James Gibson Dec 1996

Voltammetric Studies Of Mn@C82, Mark Anderson, Harry Dorn, Paul Burbank, James Gibson

Mark R. Anderson

The voltammetry for a series of related endohedral metallofullerenes is reported. It is found that as additional metal atoms are inserted into the fullerene cage, the first reduction of the metallofullerenes shifts to more negative potentials. This is consistent with more charge being transferred to the fullerene cage from the additional metal atom; however, the magnitude of the shift is much smaller than expected.

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Growth Of Bulk, Polycrystalline Gallium And Indium Nitride At Sub-Atmospheric Pressures, John Angus, Alberto Argoitia, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash Dec 1996

Growth Of Bulk, Polycrystalline Gallium And Indium Nitride At Sub-Atmospheric Pressures, John Angus, Alberto Argoitia, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash

Jeffrey Dyck

Bulk polycrystalline gallium nitride and indium nitride were crystallized at sub-atmospheric pressures by saturating the pure metals with nitrogen from a microwave electron cyclotron resonance source. Saturation of Ga/In melts with nitrogen led only to the crystallization of gallium nitride. The polycrystralline samples were wurtzitic. The gallium nitride was well faceted, with narrow Raman lineshapes, and showed near-band-edge and yellow band photo-luminescence at both 4K and 300K. The indium nitirde was formed in smaller amounts, was less well faceted, and showed no photoluminescence.

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Alte Und Neue Ungeloste Probleme In Der Zahlentheorie Und Geoetrie Der Ebene (Online), Stan Wagon Dec 1996

Alte Und Neue Ungeloste Probleme In Der Zahlentheorie Und Geoetrie Der Ebene (Online), Stan Wagon

Stan Wagon, Retired

No abstract provided.

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The Linear Potential Propagator, Br Holstein Dec 1996

The Linear Potential Propagator, Br Holstein

Barry R Holstein

The Feynman propagator for the case of a linear potential is evaluated by a variety of means.

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Uniformly Adaptive Estimation For Models With Arma Errors, Douglas Steigerwald Dec 1996

Uniformly Adaptive Estimation For Models With Arma Errors, Douglas Steigerwald

Douglas G. Steigerwald

A semiparametric estimator based on an unknown density is uniformly adaptive if the expected loss of the estimator converges to the asymptotic expected loss of the maximum likelihood estimator based on the true density (MLE), and if convergence does not depend on either the parameter values or the form of the unknown density. Without uniform adaptivity, the asymptotic expected loss of the MLE need not approximate the expected loss of a semiparamteric estimator for any finite sample. I show that a two-step semiparametric estimator is uniformly adaptive for the parameters of nonlinear regression models with autoregressive moving average errors.

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Biodiversity Monitoring: The Missing Ingredient, Kamaljit Bawa, Shaily Menon Dec 1996

Biodiversity Monitoring: The Missing Ingredient, Kamaljit Bawa, Shaily Menon

Shaily Menon

With mounting losses in biological diversity, inventorying and monitoring of biodiversity to assess the magnitude and rate of losses are emerging as dominant themes in conservation biology. Inventorying has been defined as the surveying, sorting, cataloging, quantifying and mapping of entities ranging from genes to landscapes1 and monitoring has been defined as the surveillance of the compliance with or deviation from a predetermined standard2. Renner and Ricklefs3 argued that rushed inventories will compromise scientific rigor and have little influence on decision making. More recently, Stork et al.4 argued that losses in biological diversity are so severe that inventorying and monitoring …

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The Elastic Moduli Of Random Networks: Calculations, Anthony Day Dec 1996

The Elastic Moduli Of Random Networks: Calculations, Anthony Day

Anthony Roy Day

No abstract provided.

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Mathematica In Action., Stan Wagon Dec 1996

Mathematica In Action., Stan Wagon

Stan Wagon, Retired

No abstract provided.

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A Challenge Form Leningrad, Stan Wagon Dec 1996

A Challenge Form Leningrad, Stan Wagon

Stan Wagon, Retired

No abstract provided.

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