Previous Colloquium Talks


Spring 2017


Date: 6-8-2017 (1pm-2:30pm, F03-200A), Professor Sudip Acharyya, University of Calcutta, India. 

Title: Relation between z-ideal and z^0-ideals in intermediate ring of continuous functions.

Abstract: Click here


Date: 6-6-2017 (1pm-2:30pm, F03-200A), Professor Sudip Acharyya, University of Calcutta, India. 

Title: Some new results on real valued continuous functions on a space X
whose support lie on ideals of closed sets in X.

Abstract: Click here


Date: 5-5-2017 (12-1pm, F03-200A), Dr. Eyob Demeke, Department of Mathematics, Cal State Los Angeles

Title: Proof Comprehension at the Undergraduate Level: An Exploratory Study

Abstract: This talk mainly discusses a study I conducted on proof comprehension with eleven undergraduate students. The proofs were taken from an undergraduate abstract algebra course. My interpretation of what it means to understand a proof is based on a proof comprehension model developed by Mejia-Ramos, et al. (2012). The talk, in particular, examines undergraduate students attempting to summarize a proof using its higher-level ideas. Focus is given to students’ attention to key ideas in the proof and to the method used in the proof.


Date: 4-14-2017 (12-1pm, F03-200A), Dr. Dana Clahane, Division of Mathematics & Computer Science, Fullerton College

Title: Spectra of compact composition operators on bounded symmetric domains

Abstract: In 1975, former CSULB Professor Howard Schwartz, along with James Caughran, published a now well-known result  that if a self-map induces a compact composition operator on the Hardy space of the open complex unit disk D, then two nice things happen.  First, the self-map's iterates under composition converge uniformly on compact sets to a unique fixed point in D.  Furthermore, these authors showed that in this case, the spectrum of the composition operator induced by this self-map consists of 0, 1, and all possible powers of the derivative of the self-map at this fixed point, which turns out to be the so-called Denjoy-Wolff point of the self-map.  Since then, these results have been generalized in a variety of interesting directions, such as to the unit ball in several complex dimensions.  I will define what a bounded symmetric domain is, discuss Cartan's famous classification of these domains, and state results about self-maps and spectra of their composition operators in more general situations, including the polydisk in more than one complex variable where the Denjoy-Wolff point may not exist in general.  Time permitting, I'll discuss a possible application to the Lapidus/Nest construction of so-called "fractal membranes."


Date: 3-17-2017 (12-1pm, F03-200A), Dr. Benjamin Dyhr, Department of Mathematics, Metropolitan State University

Title: Using Visual Art, Crafts and Music to Demonstrate Mathematics

Abstract: Quantitative reasoning skills are an essential component of an associate's or bachelor’s degree, but many college students do not have a personally meaningful engagement with mathematics in these courses. In some cases, student disengagement with mathematics prevents them from completing their degree. I will describe collaborative projects with Anne Hallam, MFA, from MSU Denver using math students from MSU Denver's quantitative literacy course (Mathematical Modes of Thought) and art students from MSU Denver's 2-d and 3-d Design courses. These projects can engage students and develop student ability and appreciation for mathematical communication. We will also work in groups on craft projects demonstrating mathematical concepts I have used for in-class and community events. Finally, I will describe work in progress related to similar collaborative projects that involve music.


Fall 2016


Date: 12-2-2016 (1:30-2:30pm, F03-200A), Dr. Kohei Kishida, University of Oxford

Title: Non-Locality, Contextuality, and Topology

Abstract: Non-locality and contextuality are among the most paradoxical properties of quantum physics contradicting the intuitions behind classical physics. In addition to their foundational significance, non-locality is fundamental to quantum information, and recent studies suggest contextuality is a key computational resource of quantum computation. This has motivated inquiries into higher-level, structural expressions of non-locality and contextuality that are independent of the concrete formalism of quantum mechanics. One approach uses the mathematical tool of sheaf theory, and has yielded the insight that non-locality and contextuality are topological in nature. In this talk, I first review several ideas as well as formal expressions of non-locality, and extract from them the topological formalism for quantum measurement scenarios and a characterization of non-locality in this formalism. In fact, as we show, the same characterization captures contextuality as well (so that non-locality amounts to a special case of contextuality). We will then illustrate the power of this higher-level, unifying formalism: On the one hand, it leads to several new methods of contextuality argument. On the other hand, it shows contextuality to be a ubiquitous phenomenon that can be found in various other disciplines.


Date: 11-18-2016 (12-1pm, F03-200A), Dr. Catherine Pfaff, UCSB

Title: Outer Space and the Outer Automorphism Group of the Free Group

Abstract: A common strategy for studying a group is to study some object that it acts on and how it acts on this object. My favorite group is the outer automorphism group of the free group. I will introduce this group and the object, Culler-Vogtmann Outer Space, that it acts on.


Date: 11-10-2016 Thursday (12:30-1:30pm, F03-200A), Dr. Bob Stein, Professor Emeritus of Mathematics, Cal State San Benardino

Title: The Remarkable History of Exponents and Logarithms

Abstract: Today we rarely compute with logarithms, and we take exponents largely for granted, but those topics were once at the center of mathematical interest. This talk will focus both on the development of these ideas, and on the astonishing people involved. No mathematics beyond first year calculus will be needed to understand this talk.


Date: 10-28-2016 (12-1pm, F03-200A), Dr. Lee Peterson, Jet Propulsion Laboratory

Title: Simulating Space: Role of Advanced Modeling and Uncertainty Quantification in JPL Missions

Abstract: Critical phases of spacecraft missions often cannot be completely tested on Earth, because of differences in the environments found in space and on other planetary bodies. When this happens, engineers resort to high fidelity models, informed by tests, are needed to verify readiness for flight. This talk will provide an overview of some recent applications of high fidelity models and simulations at JPL. It will include some discussion of the role of uncertainty quantification (UQ) as part of a Quantification of Margins and Uncertainties (QMU) engineering approach.


Date: 10-21-2016 (1pm-2pm, F03-200A), Dr. Khue Duong, CSULB library

Title: Data Science, Data Services, a Sabbatical Reflection

Abstract: Data comes in different sizes and formats: computer codes, spreadsheets, audio recording, images, fieldnotes, genome sequences, or geospatial coordinates. Data science, as an interdisciplinary study, incorporates many academic disciplines from mathematics and statistics to computer science, information science and geographic information system.  Furthermore, research articles from scientific journals such as Science, Nature, or PLOS One increasingly require supplementary data or pointers to data repositories where one can access the dataset for further analysis or replication of the original research.  My talk approaches data from a librarian’s perspectives and is a direct result of a four-month sabbatical to learn about how academic libraries support of data services—from providing reviews of mandated data management plans and finding discipline-specific datasets or data repositories to teaching data literacy workshops.  I hope to highlight a few resources where one can learn more about data science.

Date: 10-11-2016 (Tuesday! 12-1pm, F03-200A), Dr. Geng Chen, University of Kansas

Title: Lipschitz metric for a nonlinear wave equation

Abstract: The nonlinear wave equation: u_{tt} - c(u)[c(u)u_x]_x = 0 is a natural generalization of the linear wave equation. In this talk, we will discuss a recent breakthrough addressing the Lipschitz continuous dependence of solutions on initial data for this quasi-linear wave equation. Our earlier results showed that this equation determines a unique flow of conservative solution within the natural energy space H^1(R). However, this flow is not Lipschitz continuous with respect to the H^1 distance, due to the formation of singularity. To prove the desired Lipschitz continuous property, we constructed a new Finsler type metric, where the norm of tangent vectors is defined in terms of an optimal transportation problem. For paths of piecewise smooth solutions, we carefully estimated how the distance grows in time. To complete the construction, we proved that the family of piecewise smooth solutions is dense, following by an application of Thom's transversality theorem. This is a collaboration work with Alberto Bressan.


Date: 9-23-2016 (12-1pm, F03-200A), Dr. Gabriel Udomkesmalee, Jet Propulsion Laboratory

Title: JPL Robotics

Abstract: The Robotics Section of the Jet Propulsion Laboratory (JPL), California Institute of Technology, is engaged in a full spectrum of flight project and research activities.  This talk will provide an overview of the efforts and discuss the recent accomplishments and future directions of them.  Specific activities will be high-lighted based on their level of accomplishment, impact on the community, maturity, or novelty.  Robotics activities on flight projects are a significant subset of the full effort for these large missions.  Complementing flight activities is a diverse set of research efforts for NASA and other U.S. Government agencies. Future directions will be motivated by NASA and other sponsor objectives, as well as success experienced in these current endeavors.

Date: 9-2-2016 (12-1pm, F03-200A), Dr. Minh N. Tran, Department of Mechanical and Aerospace Engineering, UC Davis

Title: Nuclear Engineering for Everyone

Abstract: External loads are important, often well understood, and taken into account in the design of mechanical or structural components. However, there are other factors that can significantly affect the performance of materials, such as pre-existing defects and residual stresses. Those factors are usually difficulty to detect and quantify, and thus they are easy to overlook and ignore in the design phase. The work presented in this talk focuses on the residual stresses due to welding and was developed in the context of research with the nuclear power industry. Weld process models, based on nonlinear finite element computations, are frequently employed to estimate residual stresses in plant components, and those estimates are used to support plant management decisions. Therefore, we will begin with an introduction of a finite element model to predict residual stresses due to the manufacturing process of a pressurizer surge nozzle, used in the cooling system of pressurized water reactors. Modeling results are commonly evaluated at room temperature in order to validate against measurements, which are conducted at room temperature. However, in addition to weld residual stress produced in the course of manufacturing, plant components are subject to internal water pressure and elevated temperature during operation. Thus, we will next investigate the changes in weld residual stress state due to the presence of internal pressure and temperature at operating conditions. In the end, the purpose of computing residual stress is most often to determine its effect on component operability. For that reason, we will conclude the talk with a service life assessment of the pressurizer surge nozzle presented in this talk.


Spring 2016


Date: 2-19-2016 (12-1pm, F03-200A), Dr. Bogdan Suceava, California State University, Fullerton

Title: Geometry in the Dark Ages: Games of Shadows and Lights

Abstract: Isidore's Etymologies enjoyed a wide audience during the medieval period. We examine the structure of mathematics, as it is described in the Etymologies, and we discuss the sources on which Isidore relied when he collected his etymological definitions. We remark that for Isidore, mathematics is described as ``the science of learning'', and among his sources there have been the classical Greek authors, most likely available in Boethius' and Cassiodorus' Latin translations performed in the early 6th century. These translations are today lost. That's why the authors writing in the Middle Ages had to start from scratch in many of their investigations. We will illustrate this idea with one example, the discovery of curvature. In a paper published in 1952, J. L. Coolidge points out that ``the first writer to give a hint of the definition of curvature was the fourteenth century writer Nicolas Oresme". Coolidge writes further: ``Oresme conceived the curvature of a circle as inversely proportional to the radius; how did he find this out?" Tractatus de configurationibus qualitatum et motuum, written by Orseme sometime between 1351 and 1355, contains the key. We discuss N. Orseme's original work in the scholarly environment of his time, and the moment when the first definition of curvature was given.


Date: 3-4-2016 (12-1pm, F03-200A), Dr. Jim Stein, California State University, Long Beach

Title: Liberal Arts Math

At least three different approaches have been tried in liberal arts math: reinforcing previously-taught material, emphasizing topics in finite mathematics, and making students aware of new developments in the subject (which gave birth to the textbook For All Practical Purposes). None of these approaches have proved to be spectacularly successful. This talk presents a different approach to liberal arts math by setting different goals (and BTW, what are the goals of current liberal arts math courses?) and trying to achieve those goals by methods which the students taking the course may find more palatable. This won’t be the most edifying math talk you’ll ever hear – but it will be right up there when it comes to entertainment value.


Date: 4-8-2016 (2-3pm, F03-200A), Dr. Thomas Murphy, California State University, Fullerton

Title: Hearing the Shapes of Surfaces of Revolution

Abstract: Most of the talk will involve concepts from multivariable calculus, and we will mostly focus on the two-dimensional sphere. I will explain what the Laplacian is on a smooth surface, why you would want to know what its eigenvalues are, and how you can compute them. There are surprising phenomena, even for surfaces obtained by revolving a smooth curve around an axis. Time permitting, I will try outline how mathematicians wish to generalize these ideas to higher dimensions.


Date: 4-22-2016 (12-1pm, F03-200A), Dr. M. Andrew Moshier, Chapman University

Title: A Relational Category of Formal Contexts

Abstract: Formal contexts (or polarities in Birkhof’s terminology) provide a convenient combinatorial way to present closure operators on sets. They have been studied extensively for their applications to concept analysis, particularly for finite contexts, and are used regularly as a technical device in general lattice theory (for example, to describe the Dedekind-MacNeille completion of a lattice). In the most common uses, morphisms of contexts do not play a role. Although various scholars (most thoroughly, Marcel Erne ́) have considered certain notions of context morphisms, these efforts have generally concentrated either on special kinds of contexts that closely match certain “nice” lattices or on special kinds of lattice morphisms.

Here we propose a category of formal contexts in which morphisms are relations that satisfy a certain natural combinatorial property. The idea is to take our cue from the fact that a formal context is simply a binary relation between two sets. So the identity morphism of such an object should be that binary relation itself. From this, we get the combinatorial properties of morphisms more or less automatically.

The first main result of the talk is that the category of contexts is dually equivalent to the category INF, of complete meet lattices with meet-preserving maps. To get a duality with complete lattices, the second result characterizes those context morphisms that correspond to complete lattice homomorphisms.

We also consider various constructions that are well-known in INF to illustrate that formal contexts yield remarkably simple, combinatorial descriptions of many common constructions.


Date: 4-29-2016 (12-1pm, F03-200A), Dr. Wai Yan Pong, California State University, Dominguez Hills

Title: Generalized Wronskians and linear dependence of formal power series

Abstract: In this talk, I will talk about a new proof of a generalization of the following result: A family of formal power series (in several variables) are linearly independent over the field of constants if and only if some of its generalized Wronskians does not vanish. Our proof also works for quotients of germs of analytic functions. It make an interesting use of arithmetic functions and formal Dirichlet series. This is a joint work with Keith Ball and Cynthia Parks supported by Project PUMP.


Date: 5-6-2016 (12-1pm, F03-200A), Dr. Ami Radunskaya, Pomona College

Title: Clots or not? Mathematics making the invisible visible.

Abstract: Mathematical modeling is the art of representing real-world processes in mathematical terms. These abstractions can be used to understand the behavior of devices, to predict outcomes, or to test hypotheses. In this talk I will describe current work whose goal is to understand how traditional in vitro coagulation tests compare to what is actually going on in vivo. Since these in vitro tests are used to prescribe anti-coagulants, it is crucial to know whether they are indeed a measure of how quickly a clot will form. I will show how differential equations can be used to ``see” what is happening inside the blood vessel. I will discuss the mathematical challenges inherent in this type of research, as well as the potential for discovery. No expertise in mathematical modeling OR anti-coagulants is assumed. Please come join the discussion!
This is joint work with the WhAM! clotbusters research group.




Fall 2015


Date: 9-11-2015 (12-1pm, F03-200A), Dr. Hui Sun, UCSD

Title: Numerical Simulation of Solvent Stokes Flow and Solute-Solvent Interface Dynamics

Abstract: Fundamental biological molecular processes, such as protein folding, molecular recognition, and molecular assemblies, are mediated by surrounding aqueous solvent (water or salted water). Continuum description of solvent is an efficient approach to understanding such processes. In this work, we develop a solvent fluid model and computational methods for solvent dynamics and solute-solvent interface motion. The key components in our model include the Stokes equation for the incompressible solvent fluid which governs the motion of the solute-solvent interface, the ideal-gas law for solutes, and the balance on the interface of viscous force, surface tension, van der Waals type dispersive force, and electrostatic force. We use the ghost fluid method to discretize the flow equations that are reformulated into a set of Poisson equations, and design special numerical boundary conditions to solve such equations to allow the change of solute volume. We move the interface with the level-set method. To stabilize our schemes, we use the Schur complement and least-squares techniques. Numerical tests in both two and three-dimensional spaces will be shown to demonstrate the convergence of our method, and to demonstrate that this new approach can capture dry and wet hydration states as observed in experiment and molecular dynamics simulations.


Date: 10-09-2015 (12-1pm, F03-200A), Dr. Andrew J. Bernoff, Harvey Mudd College

Title: Energy driven pattern formation in thin fluid layers: The good, the bad and the beautiful

Abstract: A wide variety of physical and biological systems can be described as continuum limits of interacting particles. Their dynamics can often be described in terms of a monotonically decreasing interaction energy. We show how to exploit these energies numerically, analytically and asymptotically to characterize the observed behavior. Examples are drawn from the dynamics of thin fluid layers including ferrofluids.


Date: 10-16-2015 (2-3pm, F03-200A), Dr. Peter Jipsen, Chapman University Center of Excellence in Computation, Algebra and Topology (CECAT)

Title: From Residuated Lattices to Boolean Algebras with Operators

Abstract: This general audience talk introduces lattices and residuated operations on them, and explains how these algebraic structures are related to substructural logics. Adding some natural axioms defines Heyting algebras (corresponding to intuitionistic logic) and Boolean algebras (corresponding to classical propositional logic). No special background in abstract algebra or logic is assumed for this talk.

For many applications in logic and computer science additional operations are introduced, leading to the classical theory of Boolean algebras with operators (BAOs) as well as the still largely unexplored theory of Heyting algebras with operators (HAOs). As an example of BAOs, I will define Boolean semilattices and present some recent results about them. In the area of HAOs, generalized bunched implication algebras (GBI-algebras) are Heyting algebras expanded with a residuated monoid operation, and they have found interesting applications in the past decade in the form of separation logic for reasoning about pointers, data structures and parallel resources.

I will indicate why BAOs with a monoid operator generally lack decision procedures for their equational theories, whereas GBI-algebras, residuated lattices and several of their subclasses are equationally decidable. Some algorithms for enumerating finite algebras in these classes will be presented, as well as computational tools that are useful for exploring research questions in these areas.


Date: 10-23-2015 (12-1pm, F03-200A), Dr. Christian Rose, Technische Universität Chemnitz

Title: Compact manifolds with integral bounds on the negative part of Ricci curvature and the Kato class

Abstract: Bochner’s theorem states that a compact manifold with non-negative Ricci curvature and positive somewhere admits a trivial first cohomology group. Starting from a generalization by Elworthy and Rosenberg we show using Kato conditions for certain Schrödinger operators that L^p criteria for the part of curvature below a certain depth is sufficient that Bochner still holds.


Date: 10-30-2015 (12-1pm, F03-200A), Dr. Jasbir Chahal, Brigham Young University

Title: Two Applications of the Arithmetic of Elliptic Curves

Abstract: We will explain everything about elliptic curves needed to show how the arithmetic of elliptic curves can be used to solve two ancient problems. One is: what whole numbers are the areas of right triangles when the side lengths are allowed to be rational numbers and not just the whole numbers? The second problem is: for what triangles with all side lengths rational, an altitude, an angle bisector and the median are concurrent? No knowledge beyond high school math is required. However, the topics are very beautiful and lie at the frontier of research in number theory.


Date: 11-13-2015 (12-1pm, F03-200A), Applied Math and Statistics Graduate Students, CSULB

Title: Part I: Collaborative Filtering and the Yelp Dataset Part II: Python Introduction

Abstract: We will have a special colloquium featuring two presentations from our Applied Math and Statistics Master's students. Maike Scherer and Daniel Hallman will speak on collaborative filtering techniques for predicting user ratings of restaurants on Yelp. Juan Apitz and Truong Tran will then give an introduction to Python and the Jupyter Notebook project.


Spring 2015


Date 5-15-2015 (2pm-3pm, F03-200A), Mark Dunster, CSUSD

Title: Old and New Approximations for Bessel Functions

Abstract: Bessel functions are functions of two variables, an argument and parameter (the so-called order). They satisfy a second order linear differential equation, and also can be defined explicitly by integral representations. They are arguably the most important of the special functions, and arise naturally in a multitude of physical and mathematical applications, including heat conduction, electrostatics, scalar and electromagnetic scattering, and hydrodynamics. Here we discuss uniform asymptotic approximations involving the simpler Airy functions, which themselves are well known and important special functions. We present some classical approximations for Bessel functions, as well as some new ones for their order derivatives. The talk is accessible to upper division and graduate students having knowledge of elementary differential equations.

Date 4-24-2015 (1:30pm-2:30pm, F03-200A), Heidi Furlong and Leslie Rodriguez, CSULB

Title:Alternating Volume, a Hyperbolic Invariant of Knots

Abstract: A knot is a loop in three-dimensional space. Alternating knots are a class of knots with useful geometric properties. Using methods originally due to Blair, we define the alternating volume of a knot to be the volume of an alternating link representation of that knot. We then extend results due to Lackenby to relate the alternating volume of a knot to the twist number of a knot.

Date 4-17-2015 (12pm-1pm, F03-200A), Dr. Charis Tsikkou, West Virginia University

Title:Analysis of 2+1 Diffusive-Dispersive PDE Arising in River Braiding

Abstract: In the context of a weakly nonlinear study of bar instabilities in a river carrying sediment carrying, P. Hall introduced an evolution equation for the deposited depth which is dispersive in one spatial direction, while being diffusive in the other. In this talk, we present local existence and uniqueness results using a contraction mapping argument in a Bourgain-type space. We also show that the energy and cumulative dissipation are globally controlled in time. This is joint work with Saleh Tanveer.

Date 3-27-2015 (12pm-1pm, F03-200A), Michaela (Puck) Rombach, UCLA

Title: Graph Representatives of Positroid Strata

Abstract: This talk will be very accessible (including to grad students) and will involve juggling. The positroid stratification, studied by many authors, is a coarsening of the matroid stratification of the Grassmannian. Each graph (with orientation and edge-ordering) gives a point in the Grassmannian; for a matroid stratum to contain such a point is a well-known forbidden minor condition on the matroid. We show that, by contrast, every positroid stratum contains a graphical representative; indeed, one can choose the graph to be planar. This is despite the fact that the matroid stratum dense in the positroid stratum does not typically contain such a representative (“positroids are not graphic matroids”). Joint work with Allen Knutson.

Date 3-13-2015 (12pm-1pm, F03-200A), Shiwen Zhang, Graduate Student, UCI

Title: Can one hear the shape of a drum?---An Introduction to spectral theory in math physics

Abstract: Mark Kac raised such a problem in an article in 1966. The mathematical concept behind this problem is spectrum. Spectrum is one of many examples how physics and mathematics are so closely related. In mathematics, spectrum has been developed into deep and wide concept which is very important in several branches. The study of spectrum indeed comes from the analysis of “detectable energy level” in physics, which could be viewed as a generalization of eigenvalue problem of finite dimensional matrix. This talk intends to give a brief introduction to spectral theory towards high grade undergraduate students as well as early graduate students who are interested in math physics and related topics. I would like to introduce the rough concepts of operator and spectrum, discuss what kind of problems we are interested in spectral theory and their relation to other branches. Then I'd like to talk about the spectrum of one kind of discrete Schrodinger operator.

Date 3-6-2015 (12pm-1pm, F03-200A), Dr. Scott McCalla, Montana State University

Title: Crimes with Undergraduates

Abstract:In this talk, I will discuss two undergraduate research projects on modeling crime. The first part of the talk will concentrate on extending a model for burglary hotspot formation. Most animals, including humans, are known to make large changes in area when foraging for resources. Our extension assumes criminals will do the same when looking for possible targets to burgle. The second part will concentrate on understanding seasonal variations in crime rates. Many law enforcement personal believe simple statements like "when the temperature heats up, so does my job". We examine this ideology by extracting seasonal variations in crime rates from noisy data in the Los Angeles and Houston metropolitan areas, and then modeling this data with a stochastic differential equation.

Date 2-27-2015 (12pm-1pm, F03-200A), Paul Fish, Wolfram Technologies in Education and Research

Title: Mathematica 10 & Wolfram Alpha Pro

Abstract:This talk illustrates capabilities in Mathematica 10 and other Wolfram technologies that are directly applicable for use in teaching and research on campus.

Date 2-20-2015 (2:30pm-3:30pm, F03-200A), Casey Kelleher, UCI

Title: The Differential Geometry of the Maxwell Equations

Abstract:The Maxwell equations are a family of partial differential equations which describe the interactions of electric and magnetic fields and constitute the foundations of electromagnetic theory. While students often are introduced to this family in the physics classroom setting, these equations are seldom seen in a predominately geometric light. Approaching the Maxwell equations from this perspective is an ideal way to lay down and bolster an understanding of foundational Riemannian geometric topics, (e.g. vector fields, connections, curvature). I will both explore this viewpoint while emphasizing the underlying physical intuition.


Fall 2014


Date 12-5-2014 (12pm-1pm, F03-200A), Dr. Konstantina Trivisa, University of Maryland

Title: A Nonlinear Model for Tumor Growth: Global in time weak solutions

Abstract:We investigate the dynamics of a class of tumor growth models known as mixed models. The key characteristic of these type of tumor growth models is that the different populations of cells are continuously present everywhere in the tumor at all times. In this work we focus on the evolution of tumor growth in the presence of proliferating, quiescent and extra cellular cells as well as a nutrient. The system is given by a multi-phase flow model and the tumor is described as a growing continuum such as both the domain as well as its boundary evolve in time. Global-in-time weak solutions are obtained using an approach based on penalization of the boundary behavior, diffusion and viscosity in the weak formulation.


Date 11-14-2014 (12pm-1pm, F03-200A), Dr. Scott Crass, CSULB

Title: Dynamics of a soccer ball

Abstract: Exploiting the symmetry of the regular icosahedron, Peter Doyle and Curt McMullen constructed a solution to the quintic equation. Their algorithm relied on the dynamics of a certain icosahedrally-symmetric map for which one of the icosahedron's special orbits consists of superattracting periodic points. In this talk, we'll consider the question of whether there are maps with icosahedral symmetry with superattracting periodic points at a 60-point orbit. The investigation leads to the discovery of two maps whose superattracting sets are configurations of points that are respectively related to a soccer ball and a companion structure. It happens that a generic 60-point attractor provides for the extraction of all five of a quintic's roots.


Date 11-7-2014 (12pm-1pm, F03-200A), Dr. Mehrdad Aliasgari, CSULB

Title: Secure Computation and its Applications

Abstract: Cryptography is often described as the science of securing information in transit. However, with recent developments in computing, there is a need to provide data security in new settings. Cloud storage and cloud computing are examples of new security challenges. Secure Multiparty Computation (SMC) is when parties wish to jointly compute a function on their private input while maintaining privacy of their inputs. In this talk, we focus on cryptographic techniques that enable us to achieve security in SMC and we discuss some of their applications.


Date 10-17-2014 (12pm-1pm, F03-200A), Dr. Diane Hoffoss, University of San Diego

Title: How Wide is a 3-Manifold?

Abstract: In this talk, we will discuss some interesting ways to define the width of a 3-manifold, and we'll consider what relationships (if any!) these various definitions might have with one another.

Date 10-10-2014 (11:15am-12:15pm, F03-200A), Dr. Dominique Zosso, UCLA

Title: Variational image segmentation with dynamic artifact detection and bias correction

Abstract: Region-based image segmentation has essentially been solved by the famous Chan-Vese model. However, this model fails when images are affected by artifacts (scars, scratches, outliers) and illumination bias that outweigh the actual image contrast. Here, we introduce a new model for segmenting such damaged images: First, we introduce a dynamic artifact class X which prevents intensity outliers from skewing the segmentation. Second, in Retinex-fashion, we decompose the image into a flattened piecewise-constant structural, and a smooth bias part, I=B+S. The CV-segmentation terms are then only acting on the structure part, and only in regions not identified as artifact. We devise an efficient alternate direction minimization scheme involving averaging for S, thresholding for X, time-split MBO-like threshold dynamics for the perimeter TV-term, and spectral solutions for the bias B.

Date 10-3-2014 (12noon-1pm, F03-200A), Dr. Blake Hunter, Claremont McKenna College

Title: Topic Point Processes

Abstract: The widespread use of social media has created a need for automated extraction of useful information making detection of trends. This is essential to gain knowledge from the vastly diverse massive volume of data. This talk explores topic modeling and self-exciting time series models applied to social media microblog data. We use topic modeling and compressed sensing to discover prevalent topics and latent thematic word associations with in topics. Modeling tweet topics over time as temporal or spatial-temporal Hawkes process allows identification of self-exciting topics and reveals relationships between topics. This talk looks at applications to Twitter microblogs, text mining, image processing and content based search.

Date 9-26-2014 (3pm-4pm, F03-200A), Dr. Matt Rathbun, CSUF

Title: Knots, Fiber Surfaces, and the Building Blocks of Life

Abstract: DNA encodes the instructions used in the development and functioning of all living organisms. The DNA molecule, however, often becomes knotted, linked, and generally entangled during normal biological processes like replication and recombination. The subject of Knot Theory, correspondingly, can inform our understanding of these processes. I will introduce Knot Theory, and some of the myriad of tools that mathematicians use to understand knots and links. In particular, I will focus on a special class of link called fibered links. I will explain some recent results, joint with Dorothy Buck, Kai Ishihara, and Koya Shimokawa, about transformations from one fibered link to another, and explain how these results are relevant to microbiology.

Date 9-19-2014 (12pm-1pm, F03-200A), Dr. Ryan Compton , HRL

Title: Geotagging One Hundred Million Twitter Accounts with Total Variation Minimization

Abstract: Geographically annotated social media is extremely valuable for modern information retrieval. However, when researchers can only access publicly-visible data, one quickly finds that social media users rarely publish location information. In this work, we provide a method which can geolocate the overwhelming majority of active Twitter users, independent of their location sharing preferences, using only publicly-visible Twitter data.

Our method infers an unknown user's location by examining their friend's locations. We frame the geotagging problem as an optimization over a social network with a total variation-based objective and provide a scalable and distributed algorithm for its solution. Furthermore, we show how a robust estimate of the geographic dispersion of each user's ego network can be used as a per-user accuracy measure, allowing us to discard poor location inferences and control the overall error of our approach.

Leave-many-out evaluation shows that our method is able to infer location for 101,846,236 Twitter users at a median error of 6.33 km, allowing us to geotag over 80% of public tweets.

Date 9-12-2014 (12pm-1pm, F03-200A), Professor Ko Honda, UCLA

Title: An invitation to Floer homology

Abstract: This is a gentle introduction to Floer homology. ``Floer homology'' is a generic term for various homology theories of knots, 3- and 4-dimensional manifolds (aka spaces), symplectic manifolds, contact manifolds, etc., and has had an enormous impact in geometry/topology since its introduction by Floer more than twenty years ago. In this talk we start with a baby version of this theory called Morse homology, which gives a way to distinguish topological spaces (e.g., a sphere from the surface of a donut). We then build our way up to more recent theories such as contact homology and embedded contact homology.

Spring 2014


May 9, 2014 (12pm-1pm, F03-200A), Professor Erica Flapan, Pomona College

Title: Topological symmetry groups (Abstract)

May 2, 2014 (1pm-2pm, F03-200A), Professor Qi Zhang, UCR

Title: Recent results on axially symmetric Navier-Stokes equations (Abstract)

April 17, 2014 (1pm-2pm, F03-200A), Professor Braxton Osting, UCLA

Title: Geometric Methods for Graph Partitioning (Abstract)

February 28, 2014 (12 noon-1pm, F03-200A), Professor Zhiqin Lu, UCI

Title: The Sound of Symmetry (Abstract)


Fall 2013


December 6, 2013 (2pm-3pm, F03-200A), Professor Sam Nelson, Claremont McKenna College

Title: Augmented Birack Homology (Abstract)

November 15, 2013 (12:30pm-1:30pm, F03-200A), Nen Huynh, California State University, Long Beach

Title: A Generalized Left-to-Right (GLR) parser for Tree-Adjoining Grammars (TAG) using Matrices (Abstract)

November 8, 2013 (12:30pm-1:30pm, F03-200A), Professor Jim Hoste, Pitzer College

Title: Involutory Quandles of Knots (Abstract)

October 25, 2013 (2pm-3pm, F03-200A), Professor Kristen Hendricks, Department of Mathematics, University of California, Los Angeles

Title: Categorification and the Alexander polynomial (Abstract)

October 11, 2013 (1pm-2pm, F03-200A), Professor David Bachman, Department of Mathematics, Pitzer College

Title: From Soap Films to the Shape of Space (Abstract)

October 4, 2013 (12noon-1pm, F03-200A), Prof. John dePillis, Department of Mathematics, University of California, Riverside

Title: An Illustrated Approach to Special Relativity and Its Paradoxes (Abstract)

September 27, 2013 (12noon-1pm, F03-200A), Professor John Brevik, Department of Mathamtics and Statistics, CSULB

Title: Adventures in Noether-Lefschetz Theory II: Base Loci, Singularities, and Class Groups both Geometric and Algebraic (Joint work with Scott Nollet at TCU) (Abstract)

September 20, 2013 (12noon-1pm, F03-200A), Professor Francis Bonahon, Department of Mathematics, University of Southern California

Title: Kauffman Brackets on Surfaces (Abstract)

September 6, 2013 (12noon-1pm, F03-200A), Professor John Brevik, Department of Mathematics and Statistics, CSULB

Title: Adventures in Noether-Lefschetz Theory I: Curves, Surfaces, and Curves on Surfaces (Abstract)


Spring 2013


May 3, 2013 (12noon-1pm, F03-200A), Triet Pham, Department of Mathematics, University of Southern California

Title: A Brief Overview of Financial Mathematics (Abstract)

April 19, 2013 (12noon-1pm, F03-200A), Cynthia Northrup, University of California, Irvine

Title: Using Forcing to Obtain a Model of the Continuum Hypothesis (Abstract)

April 12, 2013 (12noon-1pm, F03-200A), Professor Demla Senturk, Department of Biostatistics, University of California, Los Angeles

Title: Cardiovascular Event Risk Dynamics Over Time in Older Patients on Dialysis: A Generalized Multiple-Index Varying Coefficient Model Approach (Abstract)

March 22, 2013 (12noon-1pm, F03-200A), Jacquelyn Rische, University of California, Irvine

Title: Mathematical Modeling of Language (Abstract)

February 15, 2013 (12noon-1pm, F03-200A), Professor Muge Kanuni, Bogazici University, Istanbul, Turkey

Title: Incidence Algebras (Abstract)

February 1, 2013 (12noon-1pm, F03-200A), Professor Ali Nadim, Institute of Mathematical Sciences, Claremont Graduate University

Title: Digital Microfluidics via Electrowetting (Abstract)

January 25, 2013 (12noon-1pm, F03-200A), Professor I-Liang Chern, Department of Mathematics, National Taiwan University

Title: Exploring Ground States and Excited States of Spin-1 Bose-Einstein Condensates (Abstract)


Fall 2012


December 7, 2012 (12noon-1pm, F03-200A), Professor Antonella Sciortino, Department of Civil Eng. and Const. Eng. Mgmt., CSULB

Title: Numerical Modeling of Transport Processes in the Subsurface (Abstract)

November 30, 2012 (12noon-1pm, F03-200A), Professor Shadnaz Asgari, Department of Computer Engineering and Computer Science, CSULB

Title: Biomedical signal processing for the improvement of health care of patients with brain-related disorders (Abstract)

November 16, 2012 (11am-12noon, F03-200A), Professor Thomas Laurent, Department of Mathematics, University of California, Riverside

Title: Machine learning, Balance cut and Total variation (Abstract)

November 9, 2012 (12noon-1pm, F03-200A), Professor Ming Ji, Graduate School of Public Health, San Diego State University

Title: Statistical Challenges in Molecular Diagnostics (Abstract)

October 19, 2012 (12noon-1pm, F03-200A), Professor James Kelliher, Department of Mathematics, University of California, Riverside

Title: Fluids and Boundaries (Abstract)

September 28, 2012 (12noon-1pm, F03-200A), Professor Robert Mena, Department of Mathematics and Statistics, CSULB

Title: A Little Big Problem in Graph Theory (Abstract)

September 21, 2012 (12noon-1pm, F03-200A), Professor Gung-Min Gie, Department of Mathematics, University of California, Riverside

Title: Motion of Fluids in the Presence of a Boundary (Abstract)


Spring 2012


May 4, 2012 (12noon-1pm, F03-200A), Dr. Arlo Caine, Department of Mathematics and Statistics, California State Polytechnic University, Pomona

Title: Mathematics and Astronomy, Kepler's Laws of Planetary Motion (Abstract)

April 20, 2012 (12noon-1pm, F03-200A), Dr. Chiu-Yen Kao, Department of Mathematics and Computer Science, Claremont Mckenna College

Title: Shape optimization problem involving principal eigenvalue in population dynamics (Abstract)

April 13, 2012 (12noon-1pm, F03-200A), Dr. Daniel Reich, Operations Research Analyst, Ford Motor Co. Research and Advanced Engineering

Title: Helping Ford’s Fleet Customers Reach Their Sustainability Goals Through Optimization (Abstract)

February 24, 2012 (12noon-1pm, F03-200A), Jeremy Jankans, University of California, Irvine

Title: How to Distinguish a Football from a Basketball Mathematically (Abstract)

February 17, 2012 (12noon-1pm, F03-200A), Professor Todd CadwalladerOlsker, Department of Mathematics, CSU, Fullerton

Title: Does a Statement of Whether Order Matters in Counting Problems Affect Students' Strategies? (Abstract)

January 27, 2012 (12noon-1pm, F03-200A), Professor Juhi Jang, University of California, Riverside

Title: Stability theory of polytropic gaseous stars (Abstract)

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