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

Physical Sciences and Mathematics Commons™

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

2010

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 8521 - 8550 of 8620

Full-Text Articles in Physical Sciences and Mathematics

List Coloring And N-Monophilic Graphs, Ramin Naimi, Radoslav Kirov Dec 2009

List Coloring And N-Monophilic Graphs, Ramin Naimi, Radoslav Kirov

Ramin Naimi

In 1990, Kostochka and Sidorenko proposed studying the smallest number of list-colorings of a graph G among all assignments of lists of a given size n to its vertices. We say a graph G is n-monophilic if this number is minimized when identical n-color lists are assigned to all vertices of G. Kostochka and Sidorenko observed that all chordal graphs are n-monophilic for all n. Donner (1992) showed that every graph is n-monophilic for all sufficiently large n. We prove that all cycles are n-monophilic for all n; we give a complete characterization of 2-monophilic graphs (which turns out to …

Go to article

Mapping And Estimation Of Chemical Concentrations In Surface Soils Using Landsat Tm Satellite Imagery, Maruthi Sridhar Balaji Bhaskar Dec 2009

Mapping And Estimation Of Chemical Concentrations In Surface Soils Using Landsat Tm Satellite Imagery, Maruthi Sridhar Balaji Bhaskar

Maruthi Sridhar Balaji Bhaskar

No abstract provided.

Go to article

Teaching Non-Mathematics Majors Using Group Topic Books, Caroline Lubert Dec 2009

Teaching Non-Mathematics Majors Using Group Topic Books, Caroline Lubert

Caroline P Lubert

No abstract provided.

Go to article

The Effect Of Salvage Therapy On Survival In A Longitudinal Study With Treatment By Indication, Edward Kennedy, Jeremy Taylor, Douglas Schaubel, Scott Williams Dec 2009

The Effect Of Salvage Therapy On Survival In A Longitudinal Study With Treatment By Indication, Edward Kennedy, Jeremy Taylor, Douglas Schaubel, Scott Williams

Edward H. Kennedy

We consider using observational data to estimate the effect of a treatment on disease recurrence, when the decision to initiate treatment is based on longitudinal factors associated with the risk of recurrence. The effect of salvage androgen deprivation therapy (SADT) on the risk of recurrence of prostate cancer is inadequately described by the existing literature. Furthermore, standard Cox regression yields biased estimates of the effect of SADT, since it is necessary to adjust for prostate-specific antigen (PSA), which is a time-dependent confounder and an intermediate variable. In this paper, we describe and compare two methods which appropriately adjust for PSA …

Go to article

Characteristics Of Methyl Cellulose-Nh4no3-Peg Electrolyte And Application In Fuel Cells, Siti Rohana Majid, Shuhaimi N. E. A., Alias N. A., Kufian M. Z., Arof A. K. Dec 2009

Characteristics Of Methyl Cellulose-Nh4no3-Peg Electrolyte And Application In Fuel Cells, Siti Rohana Majid, Shuhaimi N. E. A., Alias N. A., Kufian M. Z., Arof A. K.

Siti Rohana Majid

We report the viability of methyl cellulose (MC) as a membrane in a polymer electrolyte membrane fuel cell (PEMFC). Methyl cellulose serves as the polymer host, ammonium nitrate (NH4NO3) as the doping salt and poly(ethylene glycol) (PEG) as plasticizer. Conductivity measurement was carried out using electrochemical impedance spectroscopy. The room temperature conductivity of pure MC film is is (3.08 +/- 0.63) x 10(-11)S cm(-1). The conductivity increased to (2.10 +/- 0.37) x 10(-6)S cm(-1) on addition of 25 wt.% NH4NO3. By adding 15 wt.% of PEG 200 to the highest conducting sample in the MC-NH4NO3 system, the conductivity was further …

Go to article

Very Rapid Geomagnetic Field Change Recorded By The Partial Remagnetization Of A Lava Flow, Scott Bogue, Jonathan Glen Dec 2009

Very Rapid Geomagnetic Field Change Recorded By The Partial Remagnetization Of A Lava Flow, Scott Bogue, Jonathan Glen

Scott Bogue

A new paleomagnetic result from a lava flow with a distinctive, two-part remanence reinforces the controversial hypothesis that geomagnetic change during a polarity reversal can be much faster than normal. The 3.9-m-thick lava (“Flow 20”) is exposed in the Sheep Creek Range (north central Nevada) and was erupted during a reverse-to-normal (R-N) geomagnetic polarity switch at 15.6 Ma. Flow 20 began to acquire a primary thermoremanence while the field was pointing east and down but was soon buried, reheated, and partially-remagnetized in a north-down direction by the 8.2-m-thick flow that succeeded it. A simple conductive cooling calculation shows that the …

Go to article

Mathematica In Action: Problem-Solving Through Visualization And Computation, Stan Wagon Dec 2009

Mathematica In Action: Problem-Solving Through Visualization And Computation, Stan Wagon

Stan Wagon, Retired

No abstract provided.

Go to article

Dynamic Pickup And Delivery Problems, Gerardo Berbeglia Dec 2009

Dynamic Pickup And Delivery Problems, Gerardo Berbeglia

Gerardo Berbeglia

No abstract provided.

Go to article

Understanding Space Weather Customers In Gps-Reliant Industries, Jennifer Meehan, G. Fisher, W. Murtagh Dec 2009

Understanding Space Weather Customers In Gps-Reliant Industries, Jennifer Meehan, G. Fisher, W. Murtagh

Jennifer (Jinni) Meehan

No abstract provided.

Go to article

Kinetic And Mechanistic Studies Of The Deuterium Exchange In Classical Keto−Enol Tautomeric Equilibrium Reactions, Michael Nichols, Mark Waner Dec 2009

Kinetic And Mechanistic Studies Of The Deuterium Exchange In Classical Keto−Enol Tautomeric Equilibrium Reactions, Michael Nichols, Mark Waner

Michael A Nichols

An extension of the classic keto−enol tautomerization of β-dicarbonyl compounds into a kinetic analysis of deuterium exchange is presented. It is shown that acetylacetone and ethyl acetoacetate undergo nearly complete deuterium exchange of the α-methylene carbon when dissolved in methanol-d4. The extent of deuteration may be monitored via NMR spectroscopy as a function of time. A mechanism for deuterium exchange is presented and shown to be consistent with a consecutive first-order process. The data for acetylacetone are consistent with steady-state kinetics, whereas those of ethyl acetoacetate illustrate nonsteady-state behavior, offering an accessible example where students might collect and analyze real …

Go to article

Bismuth Compounds In Organic Synthesis: Synthesis Of Dioxanes, Dioxepines, And Dioxolanes Catalyzed By Bismuth(Iii) Triflate, Ram Mohan, Daniel Podgorski, Scott Krabbe, Long Le, Paul Sierszulski Dec 2009

Bismuth Compounds In Organic Synthesis: Synthesis Of Dioxanes, Dioxepines, And Dioxolanes Catalyzed By Bismuth(Iii) Triflate, Ram Mohan, Daniel Podgorski, Scott Krabbe, Long Le, Paul Sierszulski

Ram S. Mohan

A simple method for the synthesis of l,3-dioxolanes from carbonyl compounds has been developed using l,2-bis(trimethylsilyloxy) ethane in the presence of bismuth (III) triflate as a catalyst. The bismuth(III) triflate catalyzed synthesis of a range of dioxanes and dioxepines has also been developed. In these latter cases, the carbonyl compound is treated with a diol, and triethyl orthoformate is used as a water scavenger. All these methods avoid the use of a Dean-Stark trap.

Go to article

The Effect Of Ion-Pairing On The Open Circuit Potential Of 3-Mercaptoproprionic Acid Modified Gold Electrodes, Mark Anderson, Alice Harper Dec 2009

The Effect Of Ion-Pairing On The Open Circuit Potential Of 3-Mercaptoproprionic Acid Modified Gold Electrodes, Mark Anderson, Alice Harper

Mark R. Anderson

Open circuit potential (OCP) measurement is used to monitor the charge of a monolayer of 3-mercaptopropionic acid. OCP is determined by the concentrations of the reduced and oxidized forms of a redox couple in the solution adjacent to the modified interface. OCP values were monitored in the presence of the one-electron redox couple Fe(CN)63-/4- as a function of solution pH. The OCP measured at basic pHs was different from the acidic OCP due to differences in electrostatic interactions between the interface and the redox species as described by the Nernst equation. The influence of ion-pairing with the monolayer is studied …

Go to article

Stacking Blocks And Counting Permutations, Lara Pudwell Dec 2009

Stacking Blocks And Counting Permutations, Lara Pudwell

Lara K. Pudwell

No abstract provided.

Go to article

Categorical Approaches To Non-Commutative Fuzzy Logic, Lawrence Stout Dec 2009

Categorical Approaches To Non-Commutative Fuzzy Logic, Lawrence Stout

Lawrence N. Stout

In this paper we consider what it means for a logic to be non-commutative, how to generate examples of structures with a non-commutative operation * which have enough nice properties to serve as the truth values for a logic. Inference in the propositional logic is gotten from the categorical properties (products, coproducts, monoidal and closed structures, adjoint functors) of the categories of truth values. We then show how to extend this view of propositional logic to a predicate logic using categories of propositions about a type A with functors giving change of type and adjoints giving quantifiers. In the case …

Go to article

Kinetic And Mechanistic Studies Of The Deuterium Exchange In Classical Keto−Enol Tautomeric Equilibrium Reactions, Mark Waner, Michael Nichols Dec 2009

Kinetic And Mechanistic Studies Of The Deuterium Exchange In Classical Keto−Enol Tautomeric Equilibrium Reactions, Mark Waner, Michael Nichols

Mark J. Waner

An extension of the classic keto−enol tautomerization of β-dicarbonyl compounds into a kinetic analysis of deuterium exchange is presented. It is shown that acetylacetone and ethyl acetoacetate undergo nearly complete deuterium exchange of the α-methylene carbon when dissolved in methanol-d4. The extent of deuteration may be monitored via NMR spectroscopy as a function of time. A mechanism for deuterium exchange is presented and shown to be consistent with a consecutive first-order process. The data for acetylacetone are consistent with steady-state kinetics, whereas those of ethyl acetoacetate illustrate nonsteady-state behavior, offering an accessible example where students might collect and analyze real …

Go to article

Ans Binding Reveals Common Features Of Cytotoxic Amyloid Species, Benedetta Bolognesi, Janet Kumita, Teresa Barros, Elin Esbjorner, Leila Luheshi, Damian Crowther, Mark Wilson, Christopher Dobson, Giorgio Favrin, Justin Yerbury Dec 2009

Ans Binding Reveals Common Features Of Cytotoxic Amyloid Species, Benedetta Bolognesi, Janet Kumita, Teresa Barros, Elin Esbjorner, Leila Luheshi, Damian Crowther, Mark Wilson, Christopher Dobson, Giorgio Favrin, Justin Yerbury

Mark R Wilson

Oligomeric assemblies formed from a variety of disease-associated peptides and proteins have been strongly associated with toxicity in many neurodegenerative conditions, such as Alzheimer's disease. The precise nature of the toxic agents, however, remains still to be established. We show that prefibrillar aggregates of E22G (arctic) variant of the A beta(1-42) peptide bind strongly to 1-anilinonaphthalene 8-sulfonate and that changes in this property correlate significantly with changes in its cytotoxicity. Moreover, we show that this phenomenon is common to other amyloid systems, such as wild-type A beta(1-42), the 159T variant of human lysozyme and an SH3 domain. These findings are …

Go to article

College Algebra In Context With Applications To The Managerial, Life, And Social Sciences, Ronald Harshbarger, Lisa Yocco Dec 2009

College Algebra In Context With Applications To The Managerial, Life, And Social Sciences, Ronald Harshbarger, Lisa Yocco

Lisa S. Yocco

Harshbarger/Yocco’s College Algebra in Context with Applications for the Managerial, Life, and Social Sciences, Third Edition uses modeling and real-data problems to develop the skills that students will need for their future courses and careers. Applications anticipate the math that students will encounter in their professional lives, giving them the practice they need to become adept problem-solvers. Every chapter begins with the Algebra Toolbox, which reviews the skills and concepts necessary to master the material ahead. This new full-color edition offers a greater number of technology tips, and the content has been reorganized to accommodate a wide range of course …

Go to article

Association-Based Image Retrieval, Arun D. Kulkarni Dec 2009

Association-Based Image Retrieval, Arun D. Kulkarni

Arun Kulkarni

No abstract provided.

Go to article

Instantaneous Velocities Of A Two Body Orbit, Eric Addison Dec 2009

Instantaneous Velocities Of A Two Body Orbit, Eric Addison

Eric Addison

This short note will derive expressions for the instantaneous velocity of the components in a two-body elliptical Keplerian orbit.

Go to article

Fast Function-On-Scalar Regression With Penalized Basis Expansions, Philip T. Reiss, Lei Huang, Maarten Mennes Dec 2009

Fast Function-On-Scalar Regression With Penalized Basis Expansions, Philip T. Reiss, Lei Huang, Maarten Mennes

Lei Huang

Regression models for functional responses and scalar predictors are often fitted by means of basis functions, with quadratic roughness penalties applied to avoid overfitting. The fitting approach described by Ramsay and Silverman in the 1990s amounts to a penalized ordinary least squares (P-OLS) estimator of the coefficient functions. We recast this estimator as a generalized ridge regression estimator, and present a penalized generalized least squares (P-GLS) alternative. We describe algorithms by which both estimators can be implemented, with automatic selection of optimal smoothing parameters, in a more computationally efficient manner than has heretofore been available. We discuss pointwise confidence intervals …

Go to article

Derivation Of Initial Velocities For A Two-Body Orbit In The Barycenter Frame, Eric Addison Dec 2009

Derivation Of Initial Velocities For A Two-Body Orbit In The Barycenter Frame, Eric Addison

Eric Addison

The readily available information for two body orbits generally refers to the one dimensional, reduced mass case. Information about initial conditions in the barycenter frame is not easily found. In order to derive the initial velocities required for a two-body orbit in the barycenter frame, the momentum of the reduced mass can be used.

Go to article

A Categorical Semantics For Fuzzy Predicate Logic, Lawrence N. Stout Dec 2009

A Categorical Semantics For Fuzzy Predicate Logic, Lawrence N. Stout

Lawrence N. Stout

The object of this study is to look at categorical approaches to many valued logic, both propositional and predicate, to see how different logical properties result from different parts of the situation. In particular, the relationship between the categorical fabric I introduced at Linz in 2004 and the Fuzzy Logics studied by Hajek (2003) [5], Esteva et al. (2003) [1], and Hajek (1998) [4], comes from restricting the kind of structures used for truth values. We see how the structure of the various kinds of algebras shows up in the categorical logic, giving a variant on natural deduction for these …

Go to article

Sonic Anemometer Calibrations, Michael Negale, David Cook Dec 2009

Sonic Anemometer Calibrations, Michael Negale, David Cook

Michael Negale

Initial conditions and boundary conditions are important for climate and atmospheric modeling. In order to get correct initial and boundary conditions, correct measurements need to be made. The eddy correlation flux measurement system (ECOR) is one such system that measures fluxes in momentum, sensible heat, latent heat, and carbon dioxide (CO2). These fluxes are calculated using the eddy covariance technique, which involves wind components, air temperature, water vapor, and CO2 concentration. The ECOR uses a fast response three-dimensional wind sensor, sonic anemometer (SA), to measure wind components and speed of sound, which is used to derive the air temperature. The …

Go to article

Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward L. Chapin, Thomas R. Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher J, Conselice, Kristen Coppin, Mauro Giavalisco, David H. Hughes, Rob J. Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson Dec 2009

Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward L. Chapin, Thomas R. Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher J, Conselice, Kristen Coppin, Mauro Giavalisco, David H. Hughes, Rob J. Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson

Thushara A. Perera

We present a study of the cosmic infrared background, which is a measure of the dust obscured activity in all galaxies in the Universe. We venture to isolate the galaxies responsible for the background at 1mm; with spectroscopic and photometric redshifts we constrain the redshift distribution of these galaxies. We create a deep 1.16mm map (sigma ~ 0.5mJy) by combining the AzTEC 1.1mm and MAMBO 1.2mm datasets in GOODS-N. This combined map contains 41 secure detections, 13 of which are new. By averaging the 1.16mm flux densities of individually undetected galaxies with 24um flux densities > 25uJy, we resolve 31--45 per …

Go to article

Pleistocene To Present North Andean “Escape”, James N. Kellogg, Obi Egbue Dec 2009

Pleistocene To Present North Andean “Escape”, James N. Kellogg, Obi Egbue

James N Kellogg

This study compiles 20 published field geologic estimates of displacement rates for the northern Andes, such as displaced glacial moraines and offset pyroclastic flow, and compares them to published Global Positioning System (GPS) measurements. Dated displacements compiled in this study were obtained from the Gulf of Guayaquil, Pallatanga, Chingual-la Sofia, and Cayambe-Afiladores-Sibundoy fault systems in Ecuador and southern Colombia and the Boconó fault system in Venezuela. Right-lateral slip estimates on the individual fault segments range from 2 mm/a to 10 mm/a. The mean estimated geologic slip rate for the last 86,000 years is 7.6 mm/a. This estimate is very similar …

Go to article

A Snapshot Of Results Of The Survey Study On Rfid Technology, S. F. Wamba Dec 2009

A Snapshot Of Results Of The Survey Study On Rfid Technology, S. F. Wamba

Dr Samuel Fosso Wamba

No abstract provided.

Go to article

Spectral Decomposition Of Kac-Murdock-Szego Matrices, William F. Trench Dec 2009

Spectral Decomposition Of Kac-Murdock-Szego Matrices, William F. Trench

William F. Trench

No abstract provided.

Go to article

Enhancing The Precision Of Content Analysis In Content Adaptation Using Entropy-Based Fuzzy Reasoning, Rick C.S. Chen, Stephen J.H. Yang, Jia Zhang Dec 2009

Enhancing The Precision Of Content Analysis In Content Adaptation Using Entropy-Based Fuzzy Reasoning, Rick C.S. Chen, Stephen J.H. Yang, Jia Zhang

Jia Zhang

No abstract provided.

Go to article

Universal Two-Step Crystallization Of Dna-Functionalized Nanoparticles, Wei Dai, Sanat K. Kumar, Francis W. Starr Dec 2009

Universal Two-Step Crystallization Of Dna-Functionalized Nanoparticles, Wei Dai, Sanat K. Kumar, Francis W. Starr

Francis Starr

No abstract provided.

Go to article

Characterization And Properties Of Matrices With $K$-Involutory Symmetries Ii, William F. Trench Dec 2009

Characterization And Properties Of Matrices With $K$-Involutory Symmetries Ii, William F. Trench

William F. Trench

No abstract provided.

Go to article

First Prev Next Last