Sonja Petrovic

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With the increase in the number of cancer cases and new government regulations for cancer treatment, radiotherapy scheduling has gained a lot of importance recently. In this paper, four constructive approaches to radiotherapy scheduling are introduced, which investigates effects of changing the following parameters on the schedule performance: (1) changing(More)
We study maximum likelihood estimation for the statistical model for both directed and undirected random graph models in which the degree sequences are minimal sufficient statistics. In the undirected case, the model is known as the beta model. We derive necessary and sufficient conditions for the existence of the MLE that are based on the polytope of(More)
A reference set, or a fiber, of a contingency table is the space of all realizations of the table under a given set of constraints such as marginal totals. Understanding the geometry of this space is a key problem in algebraic statistics, important for conducting exact conditional inference, calculating cell bounds, imputing missing cell values, and(More)
We address the problem of studying the toric ideals of phylogenetic invariants for a general group-based model on an arbitrary claw tree. We focus on the group Z2 and choose a natural recursive approach that extends to other groups. The study of the lattice associated with each phylogenetic ideal produces a list of circuits that generate the corresponding(More)
Little is known about the glycosylation of the isotype switched B cell receptor (BCR) in multiple myeloma, and the way it might affect receptor function. In this work IgG BCRs isolated from the individual lysates of peripheral blood lymphocytes (PBL) of 32 patients with IgG multiple myeloma and healthy controls were investigated for the expression of sialic(More)
BACKGROUND Altered glycosylation of immunoglobulin G (IgG) has been found to affect certain immunological activities of IgG and to correlate with increased inflammation in various disease states. This work deals with the changes in distribution and galactosylation of IgG subclasses present in saliva and gingival crevicular fluid (GCF) of patients with(More)
Circulating post-switch B cells have been proposed as proliferative and disseminating progenitors in multiple myeloma. It is unclear whether the class-switched antigen receptor expressed at the surface of these cells plays a role in their expansion. In this work, the signaling status of IgG B cell receptor (BCR) isolated from the lysates of peripheral blood(More)
The p1 model is a directed random graph model used to describe dyadic interactions in a social network in terms of effects due to differential attraction (popularity) and expansiveness, as well as an additional effect due to reciprocation. In this article we carry out an algebraic statistics analysis of this model. We show that the p1 model is a toric model(More)