Partial actions on quotient spaces and globalization

Given a partial action of a topological group $G$ on a space $X$, we determine properties $\mathcal P$ which can be extended from $X$ to its globalization. We treat the cases when $\mathcal P$ is any of the following: Hausdorff, regular, metrizable, second countable and having invariant metric. Further, for a normal subgroup $H$ we introduce and study a partial action of $G/H$ on the orbit space $X/\!\sim,$ applications to invariant metrics and inverse limits are presented.Comment: 14 page

Experimental Analysis of Algorithms for Coflow Scheduling

Modern data centers face new scheduling challenges in optimizing job-level performance objectives, where a significant challenge is the scheduling of highly parallel data flows with a common performance goal (e.g., the shuffle operations in MapReduce applications). Chowdhury and Stoica introduced the coflow abstraction to capture these parallel communication patterns, and Chowdhury et al. proposed effective heuristics to schedule coflows efficiently. In our previous paper, we considered the strongly NP-hard problem of minimizing the total weighted completion time of coflows with release dates, and developed the first polynomial-time scheduling algorithms with O(1)-approximation ratios. In this paper, we carry out a comprehensive experimental analysis on a Facebook trace and extensive simulated instances to evaluate the practical performance of several algorithms for coflow scheduling, including the approximation algorithms developed in our previous paper. Our experiments suggest that simple algorithms provide effective approximations of the optimal, and that the performance of our approximation algorithms is relatively robust, near optimal, and always among the best compared with the other algorithms, in both the offline and online settings.Comment: 29 pages, 8 figures, 11 table

Influence of light nuclei on neutrino-driven supernova outflows

We study the composition of the outer layers of a protoneutron star and show that light nuclei are present in substantial amounts. The composition is dominated by nucleons, deuterons, tritons and alpha particles; 3He is present in smaller amounts. This composition can be studied in laboratory experiments with new neutron-rich radioactive beams that can reproduce similar densities and temperatures. After including the corresponding neutrino interactions, we demonstrate that light nuclei have a small impact on the average energy of the emitted electron neutrinos, but are significant for the average energy of antineutrinos. During the early post-explosion phase, the average energy of electron antineutrinos is slightly increased, while at later times during the protoneutron star cooling it is reduced by about 1 MeV. The consequences of these changes for nucleosynthesis in neutrino-driven supernova outflows are discussed

On elementary domains of partial projective representations of groups

We characterize the finite groups containing only elementary domains of factor sets of partial projective representations. A condition for a finite subset A of a group G, which contains the unity of the group, to induce an elementary partial representation, of G whose (idempotent) factor set is total is given. Finally, we characterize the elementary partial representation of abelian groups of degrees ≤ 4 with total factor set

In vitro and in vivo studies on the combination of Brequinar sodium (DUP-785; NSC 368390) with 5-fluorouracil; effects of uridine.

Brequinar sodium (DUP-785; Brequinar) is a potent inhibitor of the pyrimidine de novo enzyme dihydroorotate dehydrogenase (DHO-DH), leading to a depletion of pyrimidine nucleotides, which could be reversed by uridine. In in vitro studies we investigated the effect of different physiological concentrations of uridine on the growth-inhibition by Brequinar, the effect of the nucleoside transport inhibitor, dipyridamole, and the combination of Brequinar and 5-fluorouracil (5FU). Uridine at 1 microM slightly reversed the growth inhibition by Brequinar, while the effect of 5-500 microM was greater. However, at Brequinar concentrations greater than 30 microM, uridine could not reverse the growth-inhibitory effects. Addition of dipyridamole could only partially prevent the reversing effects of uridine. The combination of Brequinar and 5FU was more than additive in the absence of uridine in the culture medium, but not in the presence of uridine. The combination of Brequinar and 5FU was tested in vivo in two murine colon tumour models, Colon 26 and Colon 38. Scheduling of both compounds appeared to be very important. In Colon 38 no potentiating effect of Brequinar could be observed. In contrast in Colon 26 a more than additive effect could be observed. Since uridine concentrations are considerably different in these tumours (higher in Colon 38), it was concluded from both the in vitro and in vivo experiments that uridine is an important determinant in combinations of Brequinar and 5FU