Discussion on the paper “Real-Time Prediction of Clinical Trial Enrollment and Event Counts: A Review”, by DF Heitjan, Z Ge, and GS Ying

No abstract available

Single Mott Transition in Multi-Orbital Hubbard Model

The Mott transition in a multi-orbital Hubbard model involving subbands of different widths is studied within the dynamical mean field theory. Using the iterated perturbation theory for the quantum impurity problem it is shown that at low temperatures inter-orbital Coulomb interactions give rise to a single first-order transition rather than a sequence of orbital selective transitions. Impurity calculations based on the Quantum Monte Carlo method confirm this qualitative behavior. Nevertheless, at finite temperatures, the degree of metallic or insulating behavior of the subbands differs greatly. Thus, on the metallic side of the transition, the narrow band can exhibit quasi-insulating features, whereas on the insulating side the wide band exhibits pronounced bad-metal behavior. This complexity might partly explain contradictory results between several previous works.Comment: 8 pages, 11 figure

Electronic Structure and Exchange Interactions of Na2_{2}V3_{3}O7_{7}

We have performed first-principle calculations of the electronic structure and exchange couplings for the nanotube compound Na$_{2}$V$_{3}$O$_{7}$ using the LDA+U approach. Our results show that while the intra-ring exchange interactions are mainly antiferromagnetic, the inter-ring couplings are {\it ferromagnetic}. We argue that this is a consequence of the strong hybridization between filled and vacant 3d vanadium orbitals due to the low symmetry of Na$_{2}$V$_{3}$O$_{7}$, which results into strong - and often dominant - ferromagnetic contributions to the total exchange interaction between vanadium atoms. A comparison with results of previous works is included.Comment: 6 pages, 5 figure

Symplectic Cobordism in Small Dimensions and a Series of Elements of Order Four

We present the structure of symplectic cobordism ring $MSp_{*}$ in dimensions up to 51 and give a construction of an infinite series of elements $\Gamma_i$, $i=1, 3,4, ...$, of order four in this ring, where $\operatorname{dim} \, \Gamma_i=8i+95$. The key element of the series is $\Gamma_1$ in dimension 103.Comment: 117 pages, 18 table