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Articles 1501 - 1530 of 2640

Full-Text Articles in Physical Sciences and Mathematics

Direct Measurements Of Island Growth And Step-Edge Barriers In Colloidal Epitaxy, Rajesh Ganapathy, Mark R. Buckley, Sharon J. Gerbode, Itai Cohen Jan 2010

Direct Measurements Of Island Growth And Step-Edge Barriers In Colloidal Epitaxy, Rajesh Ganapathy, Mark R. Buckley, Sharon J. Gerbode, Itai Cohen

All HMC Faculty Publications and Research

Epitaxial growth, a bottom-up self-assembly process for creating surface nano- and microstructures, has been extensively studied in the context of atoms. This process, however, is also a promising route to self-assembly of nanometer- and micrometer-scale particles into microstructures that have numerous technological applications. To determine whether atomic epitaxial growth laws are applicable to the epitaxy of larger particles with attractive interactions, we investigated the nucleation and growth dynamics of colloidal crystal films with single-particle resolution. We show quantitatively that colloidal epitaxy obeys the same two-dimensional island nucleation and growth laws that govern atomic epitaxy. However, we found that in colloidal …

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Recognizing Graph Theoretic Properties With Polynomial Ideals, Jesus A. De Loera, Christopher J. Hillar, Peter N. Malkin, Mohamed Omar Jan 2010

Recognizing Graph Theoretic Properties With Polynomial Ideals, Jesus A. De Loera, Christopher J. Hillar, Peter N. Malkin, Mohamed Omar

All HMC Faculty Publications and Research

Many hard combinatorial problems can be modeled by a system of polynomial equations. N. Alon coined the term polynomial method to describe the use of nonlinear polynomials when solving combinatorial problems. We continue the exploration of the polynomial method and show how the algorithmic theory of polynomial ideals can be used to detect k-colorability, unique Hamiltonicity, and automorphism rigidity of graphs. Our techniques are diverse and involve Nullstellensatz certificates, linear algebra over finite fields, Gröbner bases, toric algebra, convex programming, and real algebraic geometry.

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Mathematical Biology At An Undergraduate Liberal Arts College, Stephen C. Adolph, Lisette G. De Pillis Jan 2010

Mathematical Biology At An Undergraduate Liberal Arts College, Stephen C. Adolph, Lisette G. De Pillis

All HMC Faculty Publications and Research

Since 2002 we have offered an undergraduate major in Mathematical Biology at Harvey Mudd College. The major was developed and is administered jointly by the mathematics and biology faculty. In this paper we describe the major, courses, and faculty and student research and discuss some of the challenges and opportunities we have experienced.

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Integrating Environmental Science Into Information Technology Content To Generate Student Interest, Rondalynne Mcclintock '13, Yoonmi Lee '12, June Hilton '04, Brian Hilton, Gondy Leroy Jan 2010

Integrating Environmental Science Into Information Technology Content To Generate Student Interest, Rondalynne Mcclintock '13, Yoonmi Lee '12, June Hilton '04, Brian Hilton, Gondy Leroy

CGU Faculty Publications and Research

In an effort to increase female student interest in computing we applied and evaluated an interdisciplinary approach at a suburban high school in eastern Los Angeles County, California. Three classes, an IB Environmental Science class, an AP Environmental Science class, and a Computer Science were surveyed to assess attitude changes toward information technology. Results indicated gender differences between the participating classes, and differences before and after the project. Although the project did not uniformly impact the attitude of female high school students, it impacted teachers who are adjusting their teaching methods, an outcome that has a long-term positive influence.

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The Effects Of Linguistic Features And Evaluation Perspective On Perceived Difficulty Of Medical Text, Gondy Leroy, Stephen Helmreich, James Cowie Jan 2010

The Effects Of Linguistic Features And Evaluation Perspective On Perceived Difficulty Of Medical Text, Gondy Leroy, Stephen Helmreich, James Cowie

CGU Faculty Publications and Research

Millions of laypersons need more medical information than they are customarily provided during their doctor’s visit. Health websites can help fill this knowledge gap, but the text is believed to be too difficult to understand for many laypersons. To help write text that is not perceived as too difficult and leads to better comprehension (actual difficulty), we study how linguistic structures influence text difficulty. Since perceived difficulty has been shown to be a barrier to self-education, evaluating perceived difficulty is an essential first step to take. In this study, we evaluated the impact of noun phrase complexity and of function …

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Eliciting User Requirements Using Appreciative Inquiry, Carol Kernitzki Gonzales Jan 2010

Eliciting User Requirements Using Appreciative Inquiry, Carol Kernitzki Gonzales

CGU Theses & Dissertations

Many software development projects fail because they do not meet the needs of users, are over-budget, and abandoned. To address this problem, the user requirements elicitation process was modified based on principles of Appreciative Inquiry. Appreciative Inquiry, commonly used in organizational development, aims to build organizations, processes, or systems based on success stories using a hopeful vision for an ideal future. Spanning five studies, Appreciative Inquiry was evaluated for its effectiveness with eliciting user requirements. In the first two cases, it was compared with traditional approaches with end-users and proxy-users. The third study was a quasi-experiment comparing the use of …

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Review: Intertwining Symmetry Algebras Of Quantum Superintegrable Systems, Gizem Karaali Jan 2010

Review: Intertwining Symmetry Algebras Of Quantum Superintegrable Systems, Gizem Karaali

Pomona Faculty Publications and Research

No abstract provided.

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Review: Nontangential Limits In Pt(Μ)-Spaces And The Index Of Invariant Subgroups, Stephan Ramon Garcia Jan 2010

Review: Nontangential Limits In Pt(Μ)-Spaces And The Index Of Invariant Subgroups, Stephan Ramon Garcia

Pomona Faculty Publications and Research

No abstract provided.

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Review: The Spectrum Of Some Compressions Of Unilateral Shifts, Stephan Ramon Garcia Jan 2010

Review: The Spectrum Of Some Compressions Of Unilateral Shifts, Stephan Ramon Garcia

Pomona Faculty Publications and Research

No abstract provided.

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Unitary Equivalence To A Complex Symmetric Matrix: Geometric Criteria, Levon Balayan '09, Stephan Ramon Garcia Jan 2010

Unitary Equivalence To A Complex Symmetric Matrix: Geometric Criteria, Levon Balayan '09, Stephan Ramon Garcia

Pomona Faculty Publications and Research

We develop several methods, based on the geometric relationship between the eigenspaces of a matrix and its adjoint, for determining whether a square matrix having distinct eigenvalues is unitarily equivalent to a complex symmetric matrix. Equivalently, we characterize those matrices having distinct eigenvalues which lie in the unitary orbit of the complex symmetric matrices.

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Some New Classes Of Complex Symmetric Operators, Stephan Ramon Garcia, Warren R. Wogen Jan 2010

Some New Classes Of Complex Symmetric Operators, Stephan Ramon Garcia, Warren R. Wogen

Pomona Faculty Publications and Research

We say that an operator $T \in B(H)$ is complex symmetric if there exists a conjugate-linear, isometric involution $C:H\to H$ so that $T = CT^*C$. We prove that binormal operators, operators that are algebraic of degree two (including all idempotents), and large classes of rank-one perturbations of normal operators are complex symmetric. From an abstract viewpoint, these results explain why the compressed shift and Volterra integration operator are complex symmetric. Finally, we attempt to describe all complex symmetric partial isometries, obtaining the sharpest possible statement given only the data $(\dim \ker T, \dim \ker T^*)$.

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Review: Common Cyclic Vectors For Unitary Operators, Stephan Ramon Garcia Jan 2010

Review: Common Cyclic Vectors For Unitary Operators, Stephan Ramon Garcia

Pomona Faculty Publications and Research

No abstract provided.

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Review: Classification Of Quasi-Trigonometric Solutions Of The Classical Yang-Baxter Equation, Gizem Karaali Jan 2010

Review: Classification Of Quasi-Trigonometric Solutions Of The Classical Yang-Baxter Equation, Gizem Karaali

Pomona Faculty Publications and Research

No abstract provided.

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Review: Quantization Of Hamiltonian-Type Lie Algebras, Gizem Karaali Jan 2010

Review: Quantization Of Hamiltonian-Type Lie Algebras, Gizem Karaali

Pomona Faculty Publications and Research

No abstract provided.

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The Norm Of A Truncated Toeplitz Operator, Stephan Ramon Garcia, William T. Ross Jan 2010

The Norm Of A Truncated Toeplitz Operator, Stephan Ramon Garcia, William T. Ross

Pomona Faculty Publications and Research

We prove several lower bounds for the norm of a truncated Toeplitz operator and obtain a curious relationship between the H2 and H∞ norms of functions in model spaces.

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Ergodic And Combinatorial Proofs Of Van Der Waerden's Theorem, Matthew Samuel Rothlisberger Jan 2010

Ergodic And Combinatorial Proofs Of Van Der Waerden's Theorem, Matthew Samuel Rothlisberger

CMC Senior Theses

Followed two different proofs of van der Waerden's theorem. Found that the two proofs yield important information about arithmetic progressions and the theorem. van der Waerden's theorem explains the occurrence of arithmetic progressions which can be used to explain such things as the Bible Code.

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Effective Environmental Management Of The National Park Service: A Case Study Of Channel Islands National Park, Daniel T. Olmsted Jan 2010

Effective Environmental Management Of The National Park Service: A Case Study Of Channel Islands National Park, Daniel T. Olmsted

CMC Senior Theses

The topic of protected area management serves as the focal point of my thesis. The fundamental question I seek to answer is; what constitutes effective environmental management and how is it exemplified in the National Park Service (NPS)? How exactly does the NPS continually earn the trust and confidence of the American people when so many other government agencies are viewed in a negative light? How does the Channel Islands National Park, in particular, shape the economic and political framework in which it operates to achieve its goals? How does this agency effectively manage such a complex ecosystem spanning across …

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Sustaining Rural Economies With Wind Development, Eric J. Van Oss Jan 2010

Sustaining Rural Economies With Wind Development, Eric J. Van Oss

CMC Senior Theses

This paper discusses the effects of wind development in rural areas. Areas of focus include: direct job creation, indirect job creation, tax revenue and government policies. The effects of state and federal renewable energy policies are discussed and well as the impacts to rural economies.

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Voting, The Symmetric Group, And Representation Theory, Zajj Daugherty '05, Alexander K. Eustis '06, Gregory Minton '08, Michael E. Orrison Dec 2009

Voting, The Symmetric Group, And Representation Theory, Zajj Daugherty '05, Alexander K. Eustis '06, Gregory Minton '08, Michael E. Orrison

All HMC Faculty Publications and Research

We show how voting may be viewed naturally from an algebraic perspective by viewing voting profiles as elements of certain well-studied QSn-modules. By using only a handful of simple combinatorial objects (e.g., tabloids) and some basic ideas from representation theory (e.g., Schur's Lemma), this allows us to recast and extend some well-known results in the field of voting theory.

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Self-Organized Criticality In Sheared Suspensions, L. Corté, Sharon J. Gerbode, W. Man, D. J. Pine Dec 2009

Self-Organized Criticality In Sheared Suspensions, L. Corté, Sharon J. Gerbode, W. Man, D. J. Pine

All HMC Faculty Publications and Research

Recent studies reveal that suspensions of neutrally buoyant non-Brownian particles driven by slow periodic shear can undergo a dynamical phase transition between a fluctuating irreversible steady state and an absorbing reversible state. Using a computer model, we show that such systems exhibit self-organized criticality when a finite particle sedimentation velocity vs is introduced. Under periodic shear, these systems evolve, without external intervention, towards the shear-dependent critical concentration ϕc as vs is reduced. This state is characterized by power-law distributions in the lifetime and size of fluctuating clusters. Experiments exhibit similar behavior and, as vs is reduced, …

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How Much Can Guided Modes Enhance Absorption In Thin Solar Cells?, Peter N. Saeta, Vivian E. Ferry, Domenico Pacifici, Jeremy N. Munday, Harry A. Atwater Nov 2009

How Much Can Guided Modes Enhance Absorption In Thin Solar Cells?, Peter N. Saeta, Vivian E. Ferry, Domenico Pacifici, Jeremy N. Munday, Harry A. Atwater

All HMC Faculty Publications and Research

Absorption enhancement in thin metal-backed solar cells caused by dipole scatterers embedded in the absorbing layer is studied using a semi-analytical approach. The method accounts for changes in the radiation rate produced by layers above and below the dipole, and treats incoherently the subsequent scattering of light in guided modes from other dipoles. We find large absorption enhancements for strongly coupled dipoles, exceeding the ergodic limit in some configurations involving lossless dipoles. An antireflection-coated 100-nm layer of a-Si:H on Ag absorbs up to 87% of incident above-gap light. Thin layers of both strong and weak absorbers show similar strongly enhanced …

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On Similarity Classes Of Well-Rounded Sublattices Of Z², Lenny Fukshansky Oct 2009

On Similarity Classes Of Well-Rounded Sublattices Of Z², Lenny Fukshansky

CMC Faculty Publications and Research

A lattice is called well-rounded if its minimal vectors span the corresponding Euclidean space. In this paper we study the similarity classes of well-rounded sublattices of Z2. We relate the set of all such similarity classes to a subset of primitive Pythagorean triples, and prove that it has the structure of a non-commutative infinitely generated monoid. We discuss the structure of a given similarity class, and define a zeta function corresponding to each similarity class. We relate it to Dedekind zeta of Z[i], and investigate the growth of some related Dirichlet series, which reflect on …

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A Preliminary Mathematical Model Of Skin Dendritic Cell Trafficking And Induction Of T Cell Immunity, Amy H. Lin Erickson, Alison Wise, Stephen Fleming, Margaret Baird, Zabeen Lateef, Annette Molinaro, Miranda Teboh-Ewungkem, Lisette G. De Pillis Sep 2009

A Preliminary Mathematical Model Of Skin Dendritic Cell Trafficking And Induction Of T Cell Immunity, Amy H. Lin Erickson, Alison Wise, Stephen Fleming, Margaret Baird, Zabeen Lateef, Annette Molinaro, Miranda Teboh-Ewungkem, Lisette G. De Pillis

All HMC Faculty Publications and Research

Chronic inflammation is a process where dendritic cells (DCs) are constantly sampling antigen in the skin and migrating to lymph nodes where they induce the activation and proliferation of T cells. The T cells then travel back to the skin where they release cytokines that induce/maintain the inflammatory condition. This process is cyclic and ongoing. We created a differential equations model to reflect the initial stages of the inflammatory process. In particular, we modeled antigen stimulation of DCs in the skin, movement of DCs from the skin to a lymph node, and the subsequent activation of T cells in the …

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Compression Theorems For Periodic Tilings And Consequences, Arthur T. Benjamin, Alex K. Eustis '06, Mark A. Shattuck Aug 2009

Compression Theorems For Periodic Tilings And Consequences, Arthur T. Benjamin, Alex K. Eustis '06, Mark A. Shattuck

All HMC Faculty Publications and Research

We consider a weighted square-and-domino tiling model obtained by assigning real number weights to the cells and boundaries of an n-board. An important special case apparently arises when these weights form periodic sequences. When the weights of an nm-tiling form sequences having period m, it is shown that such a tiling may be regarded as a meta-tiling of length n whose weights have period 1 except for the first cell (i.e., are constant). We term such a contraction of the period in going from the longer to the shorter tiling as "period compression". It turns out that …

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Asymptotic Dynamics Of Attractive-Repulsive Swarms, Andrew J. Leverentz '08, Chad M. Topaz, Andrew J. Bernoff Jul 2009

Asymptotic Dynamics Of Attractive-Repulsive Swarms, Andrew J. Leverentz '08, Chad M. Topaz, Andrew J. Bernoff

All HMC Faculty Publications and Research

We classify and predict the asymptotic dynamics of a class of swarming models. The model consists of a conservation equation in one dimension describing the movement of a population density field. The velocity is found by convolving the density with a kernel describing attractive-repulsive social interactions. The kernel’s first moment and its limiting behavior at the origin determine whether the population asymptotically spreads, contracts, or reaches steady state. For the spreading case, the dynamics approach those of the porous medium equation. The widening, compactly supported population has edges that behave like traveling waves whose speed, density, and slope we calculate. …

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A Semilinear Wave Equation With Smooth Data And No Resonance Having No Continuous Solution, Jose F. Caicedo, Alfonso Castro Jul 2009

A Semilinear Wave Equation With Smooth Data And No Resonance Having No Continuous Solution, Jose F. Caicedo, Alfonso Castro

All HMC Faculty Publications and Research

We prove that a boundary value problem for a semilinear wave equation with smooth nonlinearity, smooth forcing, and no resonance cannot have continuous solutions. Our proof shows that this is due to the non-monotonicity of the nonlinearity.

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Sum Rules And Universality In Electron-Modulated Acoustic Phonon Interaction In A Free-Standing Semiconductor Plate, Shigeyasu Uno, Darryl H. Yong, Nobuya Mori Jun 2009

Sum Rules And Universality In Electron-Modulated Acoustic Phonon Interaction In A Free-Standing Semiconductor Plate, Shigeyasu Uno, Darryl H. Yong, Nobuya Mori

All HMC Faculty Publications and Research

Analysis of acoustic phonons modulated due to the surfaces of a free-standing semiconductor plate and their deformation-potential interaction with electrons are presented. The form factor for electron-modulated acoustic phonon interaction is formulated and analyzed in detail. The form factor at zero in-plane phonon wave vector satisfies sum rules regardless of electron wave function. The form factor is larger than that calculated using bulk phonons, leading to a higher scattering rate and lower electron mobility. When properly normalized, the form factors lie on a universal curve regardless of plate thickness and material.

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The Initial And Final States Of Electron And Energy Transfer Processes: Diabatization As Motivated By System-Solvent Interactions, Joseph E. Subotnik, Robert J. Cave, Ryan P. Steele, Neil Shenvi Jun 2009

The Initial And Final States Of Electron And Energy Transfer Processes: Diabatization As Motivated By System-Solvent Interactions, Joseph E. Subotnik, Robert J. Cave, Ryan P. Steele, Neil Shenvi

All HMC Faculty Publications and Research

For a system which undergoes electron or energy transfer in a polar solvent, we define the diabatic states to be the initial and final states of the system, before and after the nonequilibrium transfer process. We consider two models for the system-solvent interactions: A solvent which is linearly polarized in space and a solvent which responds linearly to the system. From these models, we derive two new schemes for obtaining diabatic states from ab initio calculations of the isolated system in the absence of solvent. These algorithms resemble standard approaches for orbital localization, namely, the Boys and Edmiston–Ruedenberg (ER) formalisms. …

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Generation Of Mie Size Microdroplet Aerosols With Applications In Laser-Driven Fusion Experiments, Andrew P. Higginbotham '09, O. Semonin '06, S. Bruce '08, C. Chan '08, M. Maindi '07, Thomas D. Donnelly, M. Maurer, W. Bang, I. Churina, J. Osterholz, I. Kim, A. C. Bernstein, T. Ditmire Jun 2009

Generation Of Mie Size Microdroplet Aerosols With Applications In Laser-Driven Fusion Experiments, Andrew P. Higginbotham '09, O. Semonin '06, S. Bruce '08, C. Chan '08, M. Maindi '07, Thomas D. Donnelly, M. Maurer, W. Bang, I. Churina, J. Osterholz, I. Kim, A. C. Bernstein, T. Ditmire

All HMC Faculty Publications and Research

We have developed a tunable source of Mie scale microdroplet aerosols that can be used for the generation of energetic ions. To demonstrate this potential, a terawatt Ti:Al2O3 laser focused to 2×1019 W/cm2 was used to irradiate heavy water (D2O) aerosols composed of micron-scale droplets. Energetic deuterium ions, which were generated in the laser-droplet interaction, produced deuterium-deuterium fusion with approximately 2×103 fusion neutrons measured per joule of incident laser energy.

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Topics In Compressed Sensing, Deanna Needell May 2009

Topics In Compressed Sensing, Deanna Needell

CMC Faculty Publications and Research

Compressed sensing has a wide range of applications that include error correction, imaging, radar and many more. Given a sparse signal in a high dimensional space, one wishes to reconstruct that signal accurately and efficiently from a number of linear measurements much less than its actual dimension. Although in theory it is clear that this is possible, the difficulty lies in the construction of algorithms that perform the recovery efficiently, as well as determining which kind of linear measurements allow for the reconstruction. There have been two distinct major approaches to sparse recovery that each present different benefits and shortcomings. …

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