Mathematics Colloquium Schedule

Fall 2019

 

Date: 11-22-2019 (12pm-1pm, F03-200A), Dr. Gary Green, SIAM Visiting Lecture Series, retired from Aerospace Corporation.

Title: TBA

Abstract: TBA

 

Date: 11-19-2019 (Tuesday, 2pm-3pm, F03-200A), Dr. Dr. Alessandro Corbetta, Eindhoven University of Technology.

Title: TBA

Abstract: TBA

 

Date: 11-15-2019 (12pm-1pm, F03-200A), UCSD Biostats PhD program Outreach.

Title: TBA

Abstract: TBA

 

Date: 11-8-2019 (12pm-1pm, F03-200A), Dr. Shabnam Sodagari, EE Department, CSULB.

Title: TBA

Abstract: TBA

 

Date: 11-1-2019 (12pm-1pm, F03-200A), Dr. Yanxiang Zhao, George Washington University.

Title: TBA

Abstract: TBA

 

Date: 10-25-2019 (12pm-1pm, F03-200A), Dr. Yunied Puig de Dios, UC Riverside.

Title: On the interplay of functional analysis and operator theory

Abstract: We overview some basic and striking facts concerning the theory of hypercyclic operators (considered to be born in 1982):

  1. Hypercyclicity is a purely infinite-dimensional phenomenon: no finite dimensional space supports any hypercyclic operator;
  2. It is not easy at all to determine whether a linear operator is hypercyclic. However, the set of hypercyclic operators is dense for the Strong Operator Topology in the algebra of linear and bounded operators;
  3. Hypercyclicity is far from being an exotic phenomenon: any infinite-dimensional separable Frechet space supports a hypercyclic operator.
     

Date: 10-11-2019 (12pm-1pm, F03-200A), Professor Janet Duncan, UC Santa Barbara.

Title: Property/Casualty Insurance Loss Reserving Methods

Abstract: There are three fundamental methods that property/casualty actuaries utilize in estimating ultimate losses and reserves: Expected Method, Development Method, Bornhuetter-Ferguson Method. The advantage of these methods is how simple they are. In fact, all three methods pre-date computers but are still widely used and accepted because they produce reasonable results (in most cases) and are simple to explain. These days, software is used to perform the calculations. However, there is room for improvement.
 

Date: 10-04-2019 (12pm-1pm, F03-200A), Dr. Qixuan Wang, UC Riverside.

Title: Impacts of Cellular Heterogeneity on Hair Follicle Growth Dynamics

Abstract: Hair follicle is a mini-organ in mammalian skin that can undergo cyclic growth, whose spatial and temporal dynamics are under tight regulatory control mechanisms from both intra- and extra-follicular environment. Recent experimental results have elucidated how certain signaling pathways regulate cell divisions, differentiation and programmatic death in different parts of the follicle. However, an integrated regulatory mechanism of hair follicle growth dynamics is still unclear at present. In particular, two crucial questions stay unresolved: 1) how does the hair follicle know if it has reached the maximum length, and 2) how does the hair follicle know when to terminate anagen and enters catagen? Using a novel multi-scale model, we discover how a cooperative signaling network regulates the cell lineage dynamics during anagen and early catagen. Preliminary modeling results indicate that cellular heterogeneity in response to signals play an important role in controlling the hair follicle growth dynamics. In particular, we find that heterogeneity in the responses of outer root sheath cells to proliferation vs. differentiation signals determines the hair follicle length. Next, heterogeneity in the responses of matrix cells to proliferation vs. differentiation signals allows longer anagen by enhancing cell competitions. Moreover, the heterogeneous response of matrix cells to the signals allows great anagen duration variability subjected to Bmp level changes.

 

Date: 09-27-2019 (11am-12pm, F03-200A), Dr. Jiajia Dong, Bucknell University.

Title: Modeling Colony Pattern Formation under Differential Adhesion and Cell Proliferation

Abstract: Proliferation of individual cells is one of the hallmarks of living systems, and collectively the cells within a colony or tissue form highly structured patterns, influencing the properties at the population level. We develop a cellular automaton model that characterizes bacterial colony patterns emerging from the joint effect of cell proliferation and cell-cell differential adhesion. Through simulations and theoretical analysis akin to interface growth, we show that this model gives rise to novel properties consistent with recent experimental findings. We observe slower than exponential growth in the case of a single cell type as well as new colony patterns in the case of two cell types. In particular, engulfment of one cell type by the other is strongly enhanced compared to the prediction from the equilibrium differential adhesion hypothesis in the absence of proliferation. These observations provide new insights in predicting and characterizing colony morphology using experimentally accessible information such as single cell growth rate and cell adhesion strength.