### Contact Information:

Mathematics Department

The University of Tennessee at Chattanooga

415 EMCS Building, Dept. 6956

615 McCallie Ave

Chattanooga, TN 37403, USA

** E-mail:** roger-nichols "at" utc.edu

** Office:** EMCS 418A

**Phone:** (423) 425-4036

**Fax:** (423) 425-4586

### About Me:

I am an assistant professor in the Department of Mathematics at The University of Tennessee at Chattanooga.

A full CV is available here.

### Research Interests:

Spectral theory of differential operators, perturbation theory, functional analysis, semigroups, and approximation theory.

### Publications:

*Simplicity of eigenvalues in Anderson-type models*; with G. Stolz and S. Naboko. Ark. Mat.**51**, 157-183 (2013).*Spectral properties of discrete random displacement models*; with G. Stolz. J. Spectr. Theory**1**, No. 2, 123-153 (2011).*Weak convergence of spectral shift functions for one-dimensional Schrodinger operators*; with F. Gesztesy. Math. Nachr.**285**, No. 14-15, 1799-1838 (2012).*An abstract approach to weak convergence of spectral shift functions and applications to multi-dimensional**Schrodinger operators*; with F. Gesztesy. J. Spectr. Theory**2**, No. 3, 225-266 (2012).*Weyl-Titchmarsh theory for Sturm-Liouville operators with distributional potentials*; with J. Eckhardt, F. Gesztesy, and G. Teschl. Opuscula Math.**33**, No. 3, 467-563 (2013).*Heat kernel bounds for elliptic partial differential operators in divergence form with Robin-type boundary conditions*; with F. Gesztesy and M. Mitrea. J. Anal. Math.**122**, 229-287 (2014).*Inverse spectral theory for Sturm-Liouville operators with distributional potentials*; with J. Eckhardt, F. Gesztesy, and G. Teschl. J. London Math. Soc. (2)**88**, 801-828 (2013).*On square root domains for non-self-adjoint Sturm--Liouville operators*; with F. Gesztesy and S. Hofmann. Methods Funct. Anal. Topology,**19**, No. 3, 227-259 (2013).*Boundary data maps and Krein's resolvent formula for Sturm-Liouville operators on a finite interval*; with S. Clark, F. Gesztesy, and M. Zinchenko. Oper. Matrices**8**, No. 1, 1-71 (2014).*Supersymmetry and Schrodinger-type operators with**distributional matrix-valued potentials*; with J. Eckhardt, F. Gesztesy, and G. Teschl. To appear in Journal of Spectral Theory.*A Jost-Pais-type reduction of (modified) Fredholm determinants for semi-separable operators in infinite dimensions*; with F. Gesztesy. To appear in*Recent Advances in Schur Analysis and Stochastic Processes - A Collection of Papers Dedicated to Lev Sakhnovich*, D. Alpay and B. Kirstein (eds.), Operator Theory: Advances and Applications, Birkhauser, Basel.*Heat kernel bounds for elliptic partial differential operators in divergence form with Robin-type boundary conditions II*; with F. Gesztesy, M. Mitrea, and E. M. Ouhabaz. To appear in Proceedings of the American Mathematical Society.*Inverse spectral problems for Schrödinger-type operators with distributional matrix-valued potentials*; with J. Eckhardt, F. Gesztesy, A. Sakhnovich, and G. Teschl. To appear in Differential Integral Equations. [14 TeX pages].*On factorizations of analytic operator-valued functions and eigenvalue multiplicity questions*; with F. Gesztesy and H. Holden. To appear in Integral Eq. and Operator Th. [31 TeX pages].*On stability of square root domains for non-self-adjoint operators under additive perturbations*; with F. Gesztesy and S. Hofmann. To appear in Mathematika. [59 TeX pages].*Stability of square root domains associated with elliptic systems of PDEs on nonsmooth domains*; with F. Gesztesy and S. Hofmann. To appear in Journal of Differential Equations. [13 TeX pages].

### Preprints:

*Principal solutions revisited*; with S. Clark and F. Gesztesy. Submitted. [25 TeX pages].*On a problem in eigenvalue perturbation theory*; with F. Gesztesy and S. Naboko. Submitted. [8 TeX pages].

(Note: With the exception of those marked with an asterisk, all preprints are available on arXiv.org.)