Background
I hail from Bucharest, Romania. I did my undergraduate studies at the Faculty of Mathematics of the University of Bucharest. Here is a picture from those days.
For my graduate studies, I went to Columbia University, receiving my Ph.D. degree in 1984. Here is a picture from around that time, taken in Cambridge, UK.
After a J.W. Gibbs Instructorship at Yale University, I came in 1986 to Northeastern University, where I've been ever since.
Research
My research interests are in Topology, and how it relates to Algebra, Geometry, and Combinatorics.
I currently investigate cohomology jumping loci, and their applications to algebraic varieties, lowdimensional
topology, and toric topology, such as the study of hyperplane arrangements, Milnor fibrations, moment angle complexes,
configuration spaces, and various classes of knots, links, and manifolds, as well as the homology
and lower central series of discrete groups. Below are some recent papers and preprints
(click here for a complete list).

Characteristic varieties and Betti numbers of free abelian covers, Int. Math. Res. Notices (IMRN) 2014 (2014), no. 4, 10631124.

Kähler groups, quasiprojective groups, and 3manifold groups (with S. Friedl), J. London Math. Soc. 89 (2014), no. 1, 151168.

Hyperplane arrangements and Milnor fibrations, Ann. Fac. Sci. Toulouse 23 (2014), no. 2, 417481.

Multinets, parallel connections, and Milnor fibrations of arrangements (with G. Denham), Proc. London Math. Soc. 108 (2014) no. 6, 14351470.

Nonabelian resonance: product and coproduct formulas (with S. Papadima), in Bridging Algebra, Geometry, and Topology,
Springer Proceedings in Mathematics and Statistics, vol. 96, 2014, pp 269280.

Jump loci in the equivariant spectral sequence (with S. Papadima), Math. Res. Lett. 21 (2014), no. 2, 863883.

Homological finiteness of abelian covers (with Y. Yang and G. Zhao), Ann. Sc. Norm. Super. Pisa 14 (2015), no. 1, 101153.

Algebraic models, Alexandertype invariants, and GreenLazarsfeld sets (with A. Dimca and S. Papadima), Bull. Math. Soc. Sci. Math. Roumanie 58 (2015), no. 3, 257269.

Vanishing resonance and representations of Lie algebras (with S. Papadima), Crelle's Journal 706 (2015), 83101.

Torsion in the homology of Milnor fibers of hyperplane arrangements (with G. Denham), Combinatorial Methods in Topology and Algebra, 3136, Springer INdAM Series, vol. 12, Springer, Cham, 2015.

Combinatorial covers and vanishing of cohomology (with G. Denham and S. Yuzvinsky), Selecta Math. 22 (2016), no. 2, 561594.

Around the tangent cone theorem, Configurations Spaces: Geometry, Topology and Representation Theory, 139, Springer INdAM series, vol. 14, Springer, Cham, 2016.

Flat connections and resonance varieties: from rank one to higher ranks (with A.D. Macinic, S. Papadima, C.R. Popescu), to appear in Trans. Amer. Math. Soc.

The pure braid groups and their relatives (with H. Wang), to appear in Perspectives in Lie theory, Springer INdAM series.

On the topology of the Milnor fibration of a hyperplane arrangement, to appear in the proceedings of the Eighth Congress of Romanian Mathematicians.

Pure virtual braids, resonance, and formality (with H. Wang), to appear in Math. Zeit.

The Milnor fibration of a hyperplane arrangement: from modular resonance to algebraic monodromy (with S. Papadima), preprint Jan. 2014, revised April 2014.

Formality properties of finitely generated groups and Lie algebras (with H. Wang), preprint April 2015, revised August 2016.

The topology of compact Lie group actions through the lens of finite models (with S. Papadima), preprint Nov. 2015, revised June 2016.

Abelian duality and propagation of resonance (with G. Denham and S. Yuzvinsky), preprint Dec. 2015.

Residually finite rationally p groups (with T. Koberda), preprint Apr. 2016.

Naturality properties and comparison results for topological and infinitesimal embedded jump loci (with S. Papadima), preprint Sept. 2016.
Teaching
I teach a variety of math courses, both at the undergraduate and graduate level. If you are interested in taking a directed study course or a reading course with me (in addition to those courses regularly offered), please contact me.

In Spring 2013, I taught MATH 2351,
an undergraduate course in Ordinary Differential Equations, MATH 5121,
a graduate Topology 1 course, MATH 7722,
a Readings in Algebraic Topology course, and MATH 9996, a Dissertation Continuation course.

In Spring 2014, I taught MATH 4565, an undergraduate course in Topology, and MATH 9996, a Dissertation Continuation course.

In Fall 2014, I taught MATH 3150, an undergraduate course in Real Analysis,
MATH 7221, a graduate course in Topology 2, and MATH 9996, a Dissertation Continuation course.

In Spring 2015, I taught MATH 4970, a Senior Honors Project in Knot Theory, and MATH 9996, a Dissertation Continuation course.

In Fall 2015, I taught MATH 3150, an undergraduate course in Real Analysis, and
MATH 5121, a graduate Topology 1 course, and MATH 9996, a Dissertation Continuation course.

In Spring 2016, I taught MATH 4565, an undergraduate course in Topology, and MATH 9996, a Dissertation Continuation course.

In Fall 2016, I teach MATH 3150, an undergraduate course in Real Analysis, and
MATH 7221, a graduate Topology 2 course.