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2009

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Articles 6991 - 7020 of 7616

Full-Text Articles in Physical Sciences and Mathematics

Kinetics Of Co Oxidation Over Pt-Ceo_X Supported On Air-Oxidized Activated Carbon, Berri̇n Gülyüz, Şeyma Özkara Aydinoğlu, Ahmet Erhan Aksoylu, Zeynep İlsen Önsan Jan 2009

Kinetics Of Co Oxidation Over Pt-Ceo_X Supported On Air-Oxidized Activated Carbon, Berri̇n Gülyüz, Şeyma Özkara Aydinoğlu, Ahmet Erhan Aksoylu, Zeynep İlsen Önsan

Turkish Journal of Chemistry

Kinetics of low-temperature CO oxidation was studied under atmospheric pressure at 383 K in the initial rates region over 1wt%Pt-1wt%CeO_x supported on air-oxidized activated carbon (AC2). Feed concentrations of 1-5 mol% CO and 1-2.5 mol% O_2 with balance He were used for CO oxidation in the absence of hydrogen. A simple power-function rate expression was obtained with reaction orders of -0.24 in CO and 0.98 in O_2, and a plausible LHHW expression compatible with mechanisms reported in the literature was proposed. Feed concentrations of 5 mol% CO and 2.5 mol% O_2 were used for investigating the effect of the presence …

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A Systematic Study On The Absorption And Fluorescence Properties Of 2,4,6-Triaryl And Tripyridylpyridines, Esra Findik, Mustafa Arik, Mustafa Ceylan Jan 2009

A Systematic Study On The Absorption And Fluorescence Properties Of 2,4,6-Triaryl And Tripyridylpyridines, Esra Findik, Mustafa Arik, Mustafa Ceylan

Turkish Journal of Chemistry

Eight different 2,4,6-triaryl, and tripyridylpridines compounds were synthesized and their fluorescent properties were studied by using steady-state and time-resolved fluorescence and UV-Vis absorption spectroscopy techniques in 6 different solvents. Especially, 2,4,6-triarylpyridines showed strong fluorescence properties with high fluorescence quantum yields but small Stokes shifts.

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Reactions Of The Solvent-Stabilized Compound [Moocl_2(Thf)_2] With Aromatic Nitrogen Donor Ligands: Spectroscopic Characterization And Semiempirical Am1* Calculations, Gülşah Kiliçkaya, Başak Doğan, Nursel Acar, Işil Topaloğlu Sözüer Jan 2009

Reactions Of The Solvent-Stabilized Compound [Moocl_2(Thf)_2] With Aromatic Nitrogen Donor Ligands: Spectroscopic Characterization And Semiempirical Am1* Calculations, Gülşah Kiliçkaya, Başak Doğan, Nursel Acar, Işil Topaloğlu Sözüer

Turkish Journal of Chemistry

Reaction of the solvent-stabilized dioxo-molybdenum(VI) compound [MoO_2Cl_2(THF)_2] with PPh_3 yielded the oxomolybdenum(IV) species [MoOCl_2(THF)_2] (1) by the removal of one oxygen atom as PPh_3O. The complexes [MoOCl_2(=NC_6H_4CN)] 2, [MoOCl_2(CNC_6H_4OH)] 3, [MoOCl_2(=NC_6H_4NH_2)] 4, and [MoOCl_2(=NC_6H_4OCH_3)] 5, were synthesized by the reactions of [MoOCl_2(THF)_2] with XC_6H_4Y (X = NH_2, Y = CN; X= CN, Y = OH; X = Y = NH_2; X = NH_2, Y = OCH_3). All the new compounds were characterized by elemental analyses, and FTIR, UV-Vis, and ^1H- and ^{13}C-NMR spectra. Geometrical parameters and molecular orbital calculations showed that compounds 2-5 are stabilized by a charge transfer between …

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A Highly Soluble Asymmetric Perylene-Bis (Dicarboximide)-Acceptor System Incorporating A Methylene Bridged Methoxybenzene-Donor: Solvent Dependence Of Charge Transfer Interactions, Rene M. Williams Jan 2009

A Highly Soluble Asymmetric Perylene-Bis (Dicarboximide)-Acceptor System Incorporating A Methylene Bridged Methoxybenzene-Donor: Solvent Dependence Of Charge Transfer Interactions, Rene M. Williams

Turkish Journal of Chemistry

The synthesis and photophysical properties of an asymmetrically substituted perylene-bis(dicarboximide), (PDI), system (1) containing a methylene bridged 4-methoxy-benzene donor and a solubilizing branched C_{13} alkyl chain are described. As compared to most PDIs, the fluorescence of 1 is strongly quenched in polar (but not in non-polar) solvents due to a photo-induced electron transfer process. Transient absorption spectroscopy and time resolved emission in e.g. acetonitrile indicates that upon excitation the radical anion of the PDI is formed with a rate of ca. 3.5 \times 10^9s^{-1}, and the charge transfer state has a lifetime of ca. 3 ns. A Frontier Molecular Orbital …

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Pore Structure And Surface Acidity Evaluation Of Fe-Pilcs, Suna Balci, Eli̇f Gökçay Jan 2009

Pore Structure And Surface Acidity Evaluation Of Fe-Pilcs, Suna Balci, Eli̇f Gökçay

Turkish Journal of Chemistry

Fe-PILCs via different conditions using smectites from Hancili (Turkey) and Wyoming (USA) were synthesised. Presaturation had little effects on the basal spacing values while it had important effects on thermal stabilities of the products. Products having basal spacing (d_{001}) around 1.30 nm and surface area up to 160 m^2 g^{-1} were obtained. The thermal behaviour, X-ray diffraction (XRD) patterns, and nitrogen adsorption/desorption experiments confirmed that thermally stable and micro-mesoporous products were obtained although at elevated calcination temperature. Delaminated sample with basal spacing value of 2.79 nm was obtained. Surface acidity of clay was enhanced by pillaring. Chemically sorbed pyridine Fourier …

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Synthesis And Single Crystal Structure Analysis Of Three Novel Benzoylthiourea Derivatives, Gülten Kavak, Süheyla Özbey, Gün Bi̇nzet, Nevzat Külcü Jan 2009

Synthesis And Single Crystal Structure Analysis Of Three Novel Benzoylthiourea Derivatives, Gülten Kavak, Süheyla Özbey, Gün Bi̇nzet, Nevzat Külcü

Turkish Journal of Chemistry

N,N-dimethyl-N' -(2-methylbenzoyl)thiourea, C_{11}H_{14}N_2SO (HL^1), N,N-dibutyl-N' -(2-methylben\-zoyl)thiourea, C{17}H{26}N2SO (HL^2), and N,N-dihexyl-N' -(2-methylbenzoyl) thiourea, C{21}H{34}N2SO (HL^3) were synthesized and characterized by elemental analysis, spectroscopic methods (FT-IR, NMR), and single crystal X-ray diffraction. Compound HL^1 crystallizes in the monoclinic system, space group P21/c, Z = 4. Compound HL^3 also crystallizes in the monoclinic system, space group P21/n, Z = 8 with 2 independent molecules in the asymmetric unit. Compound HL^2 crystallizes in the orthorhombic system, space group Pcnn, Z = 8. In all compounds, molecules form dimers through the strong intermolecular N-H...S hydrogen bonds. Moreover, there are different types of intra- and inter-molecular …

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The Syntheses Of Methyl Jasmonate And Analogs Of Alpha-Methylene-Gamma-Butyrolactone Utilizing Titanium Medicated Cyclocarbonylation, Steve O. Lawrence Jan 2009

The Syntheses Of Methyl Jasmonate And Analogs Of Alpha-Methylene-Gamma-Butyrolactone Utilizing Titanium Medicated Cyclocarbonylation, Steve O. Lawrence

LSU Doctoral Dissertations

From its humble beginnings as a novel carbon–carbon bond forming reaction, the Pauson–Khand reaction has lead to the synthetic development of a variety of natural products. One particular variation of the Pauson–Khand reaction was called the hetero Pauson–Khand. This reaction differs from the normal Pauson–Khand reaction because the reaction employs an intramolecular titanium mediated cycloaddition using enal and enones instead of alkenes and alkynes functional groups to prepare a variety of natural products. These natural products usually contain a bicyclic cyclopentenone core. Because the new ring contains a hetero atom, the name hetero Pauson–Khand was coined. Alpha–Methylene–Gamma–Butyrolactones posses a wide …

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Topics In Quantum Optical Metrology, Aravind Chiruvelli Jan 2009

Topics In Quantum Optical Metrology, Aravind Chiruvelli

LSU Doctoral Dissertations

Quantum optical metrology deals with estimation of an unknown parameter by exploiting the non-classical properties of the light. The unknown parameter that we are trying to estimate is the optical phase. Precise optical phase measurement has been a well-known problem and has many applications, most notably the gravitational wave detection. In this thesis we investigate the interferometric measurement schemes. We consider the parity detection for a class of input states that have been shown to exhibit sub-shot noise limited phase estimate with their respective detection schemes. Our results indicate that the parity detection applies to all these strategies with various …

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A Geochemical Paleoecological Analysis Of Miocene Mammalian Mega Fauna Of Fort Polk, Louisiana, Travis Lamar Atwood Jan 2009

A Geochemical Paleoecological Analysis Of Miocene Mammalian Mega Fauna Of Fort Polk, Louisiana, Travis Lamar Atwood

LSU Master's Theses

Through a combination of vertebrate paleontology and geochemistry much can be discovered about the environments about the past. Fort Polk’s vertebrate fossil sites are important because they reflect a time when the Antarctic ice cap was just beginning to form during the middle Miocene cooling period just after the middle Miocene Climatic Optimum (~15Ma). This study tested the hypothesis that Miocene seasonality will be preserved in the isotopic geochemistry of terrestrial vertebrate remains at central North American Gulf Coastal sites. Geochemistry was used to understand fossil diagenesis, faunal communities and paleoenvironments. Fort Polk, LA sites range in age from 13.5 …

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Distribution And Habitat Associations Of Breeding Secretive Marsh Birds In The Mississippi Alluvial Valley Of Northeast Louisiana, Jonathon Joseph Valente Jan 2009

Distribution And Habitat Associations Of Breeding Secretive Marsh Birds In The Mississippi Alluvial Valley Of Northeast Louisiana, Jonathon Joseph Valente

LSU Master's Theses

Populations of many North American secretive marsh birds (SMBs) have declined over the past 30 years, primarily as a function of wetland loss. Ranges for many of these species encompass Louisiana and researchers have investigated various characteristics associated with breeding populations in coastal wetlands, yet similar knowledge is lacking for other parts of the state. I investigated distributions and habitat characteristics associated with breeding SMBs in wetlands and rice fields of the lower Mississippi Alluvial Valley (MAV) of northeast Louisiana. In the 2007 and 2008 breeding seasons we conducted repeated bird surveys in 118 wetlands and 76 rice fields. Common …

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Probabilistic Analysis Of A Motif Discovery Algorithm For Multiple Sequences, Bin Fu, Ming-Yang Kao, Lusheng Wang Jan 2009

Probabilistic Analysis Of A Motif Discovery Algorithm For Multiple Sequences, Bin Fu, Ming-Yang Kao, Lusheng Wang

Computer Science Faculty Publications and Presentations

We study a natural probabilistic model for motif discovery that has been used to experimentally test the quality of motif discovery programs. In this model, there are k background sequences, and each character in a background sequence is a random character from an alphabet Σ. A motif G = g1g2 · · · gm is a string of m characters. Each background sequence is implanted into a probabilistically generated approximate copy of G. For an approximate copy b1b2 · · · bm of G, every character bi is probabilistically generated such that the probability for r $b_i\neq g_i$ is at …

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Analyzing The Impact Of A Virtual Machine On A Host Machine, Greg Dorn, Chris Marberry, Scott Conrad, Philip Craiger Jan 2009

Analyzing The Impact Of A Virtual Machine On A Host Machine, Greg Dorn, Chris Marberry, Scott Conrad, Philip Craiger

Publications

As virtualization becomes more prevalent in the enterprise and in personal computing, there is a great need to understand the technology as well as its ramifications for recovering digital evidence. This paper focuses on trace evidence related to the installation and execution of virtual machines (VMs) on a host machine. It provides useful information regarding the types and locations of files installed by VM applications, the processes created by running VMs and the structure and identity of VMs, ancillary files and associated artifacts.

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Book Review: Escaping The Bonds Of Earth: The Fifties And The Sixties, T. D. Oswalt Jan 2009

Book Review: Escaping The Bonds Of Earth: The Fifties And The Sixties, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of by Ben Evans. Springer/Praxis, 2009 493p, 9780387790930 $39.95

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On Nonlinear Generalizations Of The Kdv And Bbm Equations From Long Range Water Wave Theory, Timothy A. Smith Jan 2009

On Nonlinear Generalizations Of The Kdv And Bbm Equations From Long Range Water Wave Theory, Timothy A. Smith

Publications

A generalization of the famous KdV and BBM equation are considered with a new nonlinear term. Sufficient conditions of solvability, existence and uniqueness are established.

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Invited Article: Data Analysis Of The Floating Potential Measurement Unit Aboard The International Space Station, Aroh Barjatya, Charles M. Swenson, Donald C. Thompson, Kenneth H. Wright Jan 2009

Invited Article: Data Analysis Of The Floating Potential Measurement Unit Aboard The International Space Station, Aroh Barjatya, Charles M. Swenson, Donald C. Thompson, Kenneth H. Wright

Publications

We present data from the Floating Potential Measurement Unit (FPMU) that is deployed on the starboard truss of the International Space Station. The FPMU is a suite of instruments capable of redundant measurements of various plasma parameters. The instrument suite consists of a floating potential probe, a wide-sweeping spherical Langmuir probe, a narrow-sweeping cylindrical Langmuir probe, and a plasma impedance probe. This paper gives a brief overview of the instrumentation and the received data quality, and then presents the algorithm used to reduce I-V curves to plasma parameters. Several hours of data are presented from August 5, 2006 and March …

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Singular Superposition/Boundary Element Method For Reconstruction Of Multi-Dimensional Heat Flux Distributions With Application To Film Cooling Holes, Mahmood Silieti, Eduardo Divo, Alain J. Kassab Jan 2009

Singular Superposition/Boundary Element Method For Reconstruction Of Multi-Dimensional Heat Flux Distributions With Application To Film Cooling Holes, Mahmood Silieti, Eduardo Divo, Alain J. Kassab

Publications

A hybrid singularity superposition/boundary element-based inverse problem method for the reconstruction of multi-dimensional heat flux distributions is developed. Cauchy conditions are imposed at exposed surfaces that are readily reached for measurements while convective boundary conditions are unknown at surfaces that are not amenable to measurements such as the walls of the cooling holes. The purpose of the inverse analysis is to determine the heat flux distribution along cooling hole surfaces. This is accomplished in an iterative process by distributing a set of singularities (sinks) inside the physical boundaries of the cooling hole (usually along cooling hole centerline) with a given …

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Statistical Analysis Of Stellar Evolution, David A. Van Dyk, Ted Von Hippel, Steven Degenarro, Nathan Stein, William Jefferys Jan 2009

Statistical Analysis Of Stellar Evolution, David A. Van Dyk, Ted Von Hippel, Steven Degenarro, Nathan Stein, William Jefferys

Publications

Color-Magnitude Diagrams (CMDs) are plots that compare the magnitudes (luminosities) of stars in different wavelengths of light (colors). High nonlinear correlations among the mass, color, and surface temperature of newly formed stars induce a long narrow curved point cloud in a CMD known as the main sequence. Aging stars form new CMD groups of red giants and white dwarfs. The physical processes that govern this evolution can be described with mathematical models and explored using complex computer models. These calculations are designed to predict the plotted magnitudes as a function of parameters of scientific interest, such as stellar age, mass, …

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Review: Spectra Of Toeplitz Operators And Compositions Of Muckenhoupt Weights With Blaschke Products, Stephan Ramon Garcia Jan 2009

Review: Spectra Of Toeplitz Operators And Compositions Of Muckenhoupt Weights With Blaschke Products, Stephan Ramon Garcia

Pomona Faculty Publications and Research

No abstract provided.

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Truncated Toeplitz Operators: Spatial Isomorphism, Unitary Equivalence, And Similarity, Joseph A. Cima, Stephan Ramon Garcia, William T. Ross, Warren R. Wogen Jan 2009

Truncated Toeplitz Operators: Spatial Isomorphism, Unitary Equivalence, And Similarity, Joseph A. Cima, Stephan Ramon Garcia, William T. Ross, Warren R. Wogen

Pomona Faculty Publications and Research

A truncated Toeplitz operator A φ : K Θ → K Θ is the compression of a Toeplitz operator T φ : H 2 → H 2 to a model space K Θ ≔ H 2 ⊖ Θ H 2 . For Θ inner, let T Θ denote the set of all bounded truncated Toeplitz operators on K Θ . Our main result is a necessary and sufficient condition on inner functions Θ 1 and Θ 2 which guarantees that T Θ 1 and T Θ 2 are spatially isomorphic (i.e., U T Θ 1 = T Θ 2 U …

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The Norm And Modulus Of A Foguel Operator, Stephan Ramon Garcia Jan 2009

The Norm And Modulus Of A Foguel Operator, Stephan Ramon Garcia

Pomona Faculty Publications and Research

We develop a method for calculating the norm and the spectrum of the modulus of a Foguel operator. In many cases, the norm can be computed exactly. In others, sharp upper bounds are obtained. In particular, we observe several connections between Foguel operators and the Golden Ratio.

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A New Elasticity Element Made For Enforcing Weak Stress Symmetry, Bernardo Cockburn, Jay Gopalakrishnan, Johnny Guzmán Jan 2009

A New Elasticity Element Made For Enforcing Weak Stress Symmetry, Bernardo Cockburn, Jay Gopalakrishnan, Johnny Guzmán

Mathematics and Statistics Faculty Publications and Presentations

We introduce a new mixed method for linear elasticity. The novelty is a simplicial element for the approximate stress. For every positive integer k, the row-wise divergence of the element space spans the set of polynomials of total degree k. The degrees of freedom are suited to achieve continuity of the normal stresses. What makes the element distinctive is that its dimension is the smallest required for enforcing a weak symmetry condition on the approximate stress. This is achieved using certain "bubble matrices", which are special divergence-free matrix-valued polynomials. We prove that the approximation error is of order k + …

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Polynomial Extension Operators. Part Ii, Leszek Demkowicz, Jay Gopalakrishnan, Joachim Schöberl Jan 2009

Polynomial Extension Operators. Part Ii, Leszek Demkowicz, Jay Gopalakrishnan, Joachim Schöberl

Mathematics and Statistics Faculty Publications and Presentations

Consider the tangential trace of a vector polynomial on the surface of a tetrahedron. We construct an extension operator that extends such a trace function into a polynomial on the tetrahedron. This operator can be continuously extended to the trace space of H(curl ). Furthermore, it satisfies a commutativity property with an extension operator we constructed in Part I of this series. Such extensions are a fundamental ingredient of high order finite element analysis.

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The Derivation Of Hybridizable Discontinuous Galerkin Methods For Stokes Flow, Bernardo Cockburn, Jay Gopalakrishnan Jan 2009

The Derivation Of Hybridizable Discontinuous Galerkin Methods For Stokes Flow, Bernardo Cockburn, Jay Gopalakrishnan

Mathematics and Statistics Faculty Publications and Presentations

In this paper, we introduce a new class of discontinuous Galerkin methods for the Stokes equations. The main feature of these methods is that they can be implemented in an efficient way through a hybridization procedure which reduces the globally coupled unknowns to certain approximations on the element boundaries. We present four ways of hybridizing the methods, which differ by the choice of the globally coupled unknowns. Classical methods for the Stokes equations can be thought of as limiting cases of these new methods.

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Stability Of Linear Flocks On A Ring Road, J. J. P. Veerman, Carlos Martins Da Fonseca Jan 2009

Stability Of Linear Flocks On A Ring Road, J. J. P. Veerman, Carlos Martins Da Fonseca

Mathematics and Statistics Faculty Publications and Presentations

We discuss some stability problems when each agent of a linear flock on the line interacts with its two nearest neighbors (one on either side).

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Review: Dynamical Yang-Baxter Maps With An Invariance Condition, Gizem Karaali Jan 2009

Review: Dynamical Yang-Baxter Maps With An Invariance Condition, Gizem Karaali

Pomona Faculty Publications and Research

No abstract provided.

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Development Of The Curriculum For The Introduction To Computer Science Course, Nancy Major Jan 2009

Development Of The Curriculum For The Introduction To Computer Science Course, Nancy Major

Regis University Student Publications (comprehensive collection)

This project proposes to reformat the curriculum for an Introduction to Computer Science course for high school students, currently taught as a one semester course. Several issues with the current course are addressed with recommendations for changes intended for the benefit of students at their school. In the past five years, enrollment in the school's Advanced Placement (AP) Computer Science course has decreased from 50 students to 25 students despite no significant change in overall enrollment or student demographics. For the portion of those students enrolled in the course who have taken the Advanced Placement exam during the past four …

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A Strategy For Reducing I/O And Improving Query Processing Time In An Oracle Data Warehouse Environment, Chris Titus Jan 2009

A Strategy For Reducing I/O And Improving Query Processing Time In An Oracle Data Warehouse Environment, Chris Titus

Regis University Student Publications (comprehensive collection)

In the current information age as the saying goes, time is money. For the modern information worker, decisions must often be made quickly. Every extra minute spent waiting for critical data could mean the difference between financial gain and financial ruin. Despite the importance of timely data retrieval, many organizations lack even a basic strategy for improving the performance of their data warehouse based reporting systems. This project explores the idea that a strategy making use of three database performance improvement techniques can reduce I/O (input/output operations) and improve query processing time in an information system designed for reporting. To …

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A Single Particle Impact Model For Motion In Avalanches, J. J. P. Veerman, Dacian Daescu, M. J. Romero-Vallés, P. J. Torres Jan 2009

A Single Particle Impact Model For Motion In Avalanches, J. J. P. Veerman, Dacian Daescu, M. J. Romero-Vallés, P. J. Torres

Mathematics and Statistics Faculty Publications and Presentations

We describe the global behavior of the dynamics of a particle bouncing down an inclined staircase. For small inclinations all orbits eventually stop (independent of the initial condition). For large enough inclinations all orbits end up accelerating indefinitely (also independent of the initial conditions). There is an interval of inclinations of positive length between these two. In that interval the behavior of an orbit depends on its initial condition. In addition to stopping and accelerating orbits, there are also orbits with speeds bounded away from both zero and infinity. A second hallmark of the dynamics is that the orbits going …

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Predicting The Drug Release Kinetics Of Matrix Tablets, Boris Baeumer, Lipika Chatterjee, Peter Hinow, Thomas Rades, Ami E. Radunskaya, Ian Tucker Jan 2009

Predicting The Drug Release Kinetics Of Matrix Tablets, Boris Baeumer, Lipika Chatterjee, Peter Hinow, Thomas Rades, Ami E. Radunskaya, Ian Tucker

Pomona Faculty Publications and Research

In this paper we develop two mathematical models to predict the release kinetics of a water soluble drug from a polymer/excipient matrix tablet. The first of our models consists of a random walk on a weighted graph, where the vertices of the graph represent particles of a drug, excipient and polymer, respectively. The graph itself is the contact graph of a multidisperse random sphere packing. The second model describes the dissolution and the subsequent diffusion of the active drug out of a porous matrix using a system of a partial differential equations. The predictions of both models show good qualitative …

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Review: Hankel And Toeplitz Transforms On H¹: Continuity, Compactness And Fredholm Properties, Stephan Ramon Garcia Jan 2009

Review: Hankel And Toeplitz Transforms On H¹: Continuity, Compactness And Fredholm Properties, Stephan Ramon Garcia

Pomona Faculty Publications and Research

No abstract provided.

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