Dibyen Majumdar

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Shill bidding has become a serious issue for innocent bidders with the growing popularity of online auctions. In this paper, we study the relationship between final prices of online auctions and shill activities. We conduct experiments on real auction data from eBay to examine the hypotheses that state how the difference between final auction price and(More)
Previous studies on event-related functional magnetic resonance imaging experimental designs are primarily based on linear models, in which a known shape of the hemodynamic response function (HRF) is assumed. However, the HRF shape is usually uncertain at the design stage. To address this issue , we consider a nonlinear model to accommodate a wide spectrum(More)
PURPOSE This was a pilot study conducted to examine the expression of osteopontin in uveal melanoma and to determine whether serum osteopontin can be used in detecting metastatic uveal melanoma. METHODS Osteopontin mRNA was measured in three uveal melanoma cell lines of various invasive potential by real-time PCR. Tissue sections of primary and metastatic(More)
PURPOSE To model the behavior of uveal melanoma in the liver. METHODS A 15-muL suspension of metastatic MUM2B or either primary OCM1 or M619 uveal melanoma cells was injected into the liver parenchyma of 105 CB17 SCID mice through a 1-cm abdominal incision. Animals were killed at 2, 4, 6, or 8 weeks after injection. Before euthanatization, 3% FITC-BSA(More)
PURPOSE Aggressive melanoma cells may express endothelial markers that can be used to calculate microvascular density (MVD). High MVD has been associated with adverse outcome in uveal melanoma. If tumor cells label with endothelial cell markers, then MVD may not accurately reflect a tumor's vascularity. This study was designed to study the influence of(More)
Low, Lewis and Prescott (1999) showed that a crossover design based on a Williams Latin square of order 4 can suffer substantial loss of efficiency if some observations in the final period are unavailable. Indeed, if all observations are missing, the design becomes disconnected. We derive the information matrix for the direct effects of a Uniformly Balanced(More)
We consider the problem of obtaining locally D-optimal designs for factorial experiments with qualitative factors at two levels, each with binary response. For the 2 2 factorial experiment with main effects model, we obtain optimal designs analytically in special cases and demonstrate how to obtain a solution in the general case using cylindrical algebraic(More)