171,579 research outputs found
Broadcast scheduling for mobile advertising
We describe a broadcast scheduling system developed for a precision marketing firm specialized in location-sensitive permission-based mobile advertising using SMS (Short Message Service) text messaging. Text messages containing advertisements were sent to registered customers when they were shopping in one of two shopping centers in the vicinity of London. The ads typically contained a limited-time promotional offer. The company's problem was deciding which ads to send out to which customers at what particular time, given a limited capacity of broadcast time slots, while maximizing customer response and revenues from retailers paying for each ad broadcast. We solved the problem using integer programming with an interface in Microsoft Excel. The system significantly reduced the time required to schedule the broadcasts, and resulted both in increased customer response and revenues
LLAGN and jet-scaling probed with the EVN
Accreting black holes on all mass scales (from stellar to supermassive)
appear to follow a nonlinear relation between X-ray luminosity, radio
luminosity and BH mass, indicating that similar physical processes drive the
central engines in X-ray binaries and active galactic nuclei (AGN). However, in
recent years an increasing number of BH systems have been identified that do
not fit into this scheme. These outliers may be the key to understand how BH
systems are powered by accretion. Here we present results from EVN observations
of a sample of low-luminosity AGN (LLAGN) with known mass that have unusually
high radio powers when compared with their X-ray luminosity.Comment: Presented at the 11th EVN Symposium, Bordeaux, France, 2012 October
9-12. Six pages, including a figure and a table. Final, accepted versio
Nesting maps of Grassmannians
Let F be a field and i < j be integers between 1 and n. A map of
Grassmannians f : Gr(i, F^n) --> Gr(j, F^n) is called nesting, if l is
contained in f(l) for every l in Gr(i, F^n). We show that there are no
continuous nesting maps over C and no algebraic nesting maps over any
algebraically closed field F, except for a few obvious ones. The continuous
case is due to Stong and Grover-Homer-Stong; the algebraic case in
characteristic zero can also be deduced from their results. In this paper we
give new proofs that work in arbitrary characteristic. As a corollary, we give
a description of the algebraic subbundles of the tangent bundle to the
projective space P^n over F. Another application can be found in a recent paper
math.AC/0306126 of George Bergman
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