READINESS ASSESSMENT AND COURSE PLACEMENT THROUGH INTRODUCTORY CALCULUS

Speaker: 

Professor Alison Ahlgren

Institution: 

UIUC

Time: 

Tuesday, February 9, 2010 - 4:00pm

Location: 

RH 306

Theory of knowledge and learning spaces is used to assess readiness and de-
termine course placement for mathematics students at or below introductory calculus at
the University of Illinois. Readiness assessment is determined by the articially intelligent
system ALEKS. The ALEKS-based mechanism used at the University of Illinois eectively
reduces overplacement and is more eective than the previously used ACT-based mech-
anism. Signicant enrollment distribution changes occured as a result of the mechanism
implementation. ALEKS assessments provide more specic skill information than the ACT.
Correlations of ALEKS subscores with student maturity and performance meets explecta-
tions in many cases, and revels interesting characteristics of the student population in other
(systematic weakness in exponentials and logarithms). ALEKS revels skill bimodality in the
population not captured by the previous placement mechanism.
The data shows that preparation, as measured by ALEKS, correlates positively with
course performance, and more strongly than the ACT in general. The trending indicates
that while a student may pass a course with a lower percentage of prerequisite concepts
known, students receiving grades of A or B generally show greater preparedness. Longi-
tudinal comparison of students taking Precalculus shows that ALEKS assessments are an
eective measure of knowledge increase. Calculus students with weaker skills can be brought
to the skill level of their peers, as measured by ALEKS, by taking a preparatory course.
Interestingly, the data provided by ALEKS provides a measure of course eectiveness when
students preformance is aggregated and tracked longitudinally. The data is also used to
measure course eectiveness and visualize the aggregate skills of student populations.

Geometry, fluids, control, optimization, and imaging

Speaker: 

Tudor Ratiu

Institution: 

Ecole Polytechnique Federale de Lausanne

Time: 

Thursday, January 7, 2010 - 4:00pm

Location: 

RH 306

Variational principles are at the core of the formulation of mechanical problems. What happens in the presence of symmetry when variables can be eliminated? I will discuss the geometry underlying this reduction process and present the induced constrained variational principle and the associated Euler-Lagrange equations. The rigid body and the Euler equations for ideal fluids are examples of such reduced Euler-Lagrange equations in convective and spatial representations, respectively. This geometric structure permits the introduction of a new class of optimal control problems that have the remarkable property that the control satisfies precisely these reduced Euler-Lagrange equations. As an example, it is shown that geodesic motion for the normal metric can be controlled by geodesics on the symmetry group. In the case of fluids, these optimal control problems yield the classical Clebsch variables and singular solutions for the Camassa-Holm equation. Relaxing the constraint to a quadratic penalty yields associated optimization problems. Time permitting, the equations of metamorphosis dynamics in imaging will be deduced from this optimization problem.

Mathematics of quantum resonances

Speaker: 

Maciej Zworski

Institution: 

UC Berkeley

Time: 

Thursday, February 18, 2010 - 4:00pm

Location: 

RH 306

Quantum resonances describe metastable states created by phenomena such as tunnelling, radiation, or trapping of classical orbits. Mathematically they are elegantly defined as poles of meromorphically continued operators such as the resolvent or the scattering matrix: the real part of the pole gives the rest energy or frequency, and the imaginary part, the rate of decay. With that interpretation they appear in expansions of linear and non-linear waves. And they can be found in other branches of mathematics and science: as poles of Eisenstein series and zeta functions in geometric analysis, scattering poles in acoustical and electromagnetic scattering, Ruelle resonances in dynamical systems, and quasinormal modes in the theory of black holes. In my talk I will present some basic concepts and illustrate recent mathematical advances with numerical and experimental examples.

Kinetic evolution of multi-linear particle interactive dynamics

Speaker: 

Irene Gamba

Institution: 

University of Texas at Austin

Time: 

Thursday, May 14, 2009 - 4:00pm

Location: 

RH 306

We shall revisit the Boltzmann equation for rarefied non-linear particle dynamics, of conservative or dissipative nature, and on the stochastic N-particle model, introduced by M. Kac.
Related to this equation, we consider a a probabilistic dynamics from generalizations to N-particle model which includes multi-particle interactions. From basic symmetries and invariances for a general class of stochastic interactions, we show existence and uniqueness of states and recover the longtime dynamics and decay rates approaching stable laws characterized by self-similar rescaling, with finite or infinity energy initial data. We classify the moments integrability and see that broad tails (Pareto type) attractors are possible.

There is a large class of applications to these models including classical elastic or inelastic Maxwell type interactions with or without a thermostat, and social dynamics such as information percolation models, or wealth distributions models with Pareto tail formation.

This is work in collaboration with A. Bobylev, C. Cercignani and H. Tharkabhushanam.

Space of Ricci flows

Speaker: 

Professor Xiuxiong Chen

Institution: 

Wisconsin

Time: 

Thursday, February 26, 2009 - 4:00pm

Location: 

RH 306

Inspired by the canonical neighborhood theorem of G. Perelman in 3 dimensional, we study the weak compactness of sequence of ricci flow with scalar curvature bound, Kappa non-collapsing and integral curvature bound.

All of these constraints are natural in the Kahler ricci flow in Fano surface and as an application, we give a ricci flow based proof to the Calabi conjecture in Fano surface.

Self assembly and sphere packings

Speaker: 

Michael Brenner

Institution: 

Harvard University

Time: 

Thursday, October 22, 2009 - 4:00pm

Location: 

RH 306

Self assembly is the idea of creating a system whose component parts spontaneously assemble into a structure of interest. In this talk I will outline our research program aimed at creating self-assembled structures out of very small spheres, that bind to each other on sticking. The talk will focus on

(i) some fundamental mathematical questions in finite sphere packings (e.g. how do the number of rigid packings grow with N, the number of spheres);

(ii) algorithms for self assembly (e.g. suppose the spheres are not identical, so that every sphere does not stick to every other; how to design the system to promote particular structures);

(iii) physical questions (e.g. what is the probability that a given packing with N particles forms for a system of colloidal nanospheres); and

(iv) comparisons with experiments on colloidal nanospheres.

Homology of invariant foliations and its applications to dynamics

Speaker: 

Professor Zhihong Jeff Xia

Institution: 

Northwestern University

Time: 

Thursday, April 30, 2009 - 4:00pm

Location: 

RH 306

We define a new topological invariant for foliations of a compact manifold. This invariant is used to prove several interesting results in dynamical systems.
This talk will be accessible to all graduate students in mathematics.

Many-body wave scattering by small bodies and creating materials with a desired refraction coefficient

Speaker: 

Alexander Ramm

Institution: 

Kansas State University

Time: 

Thursday, February 5, 2009 - 4:00pm

Location: 

RH 306

Many-body scattering problem is solved asymptotically when the size of the particles tends to zero and the number of the particles tends to infinity.
A method is given for calculation of the number of small particles and their boundary impedances such that embedding of these particles in a bounded domain, filled with known material, results in creating a new material with a desired refraction coefficient.
iThe new material may be created so that it has negative refraction, that is, the group velocity in this material is directed opposite to the phase velocity.
Another possible application consists of creating the new material with some desired wave-focusing properties. For example, one can create a new material which scatters plane wave mostly in a fixed given solid angle. In this application it is assumed that the incident plane wave has a fixed frequency and a fixed incident direction.
An inverse scattering problem with scattering data given at a fixed wave number and at a fixed incident direction is formulated and solved. Acoustic and electromagnetic (EM) wave scattering problems are discussed.

A.G.Ramm's vita, list of publications and some papers can be printed from the Internet address http://www.math.ksu.edu/~ramm

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