Composition Operators on the Dirichlet Space and Related Problems

In this paper we investigate the following problem: when a bounded analytic function $\phi$ on the unit disk $\mathbb{D}$, fixing 0, is such that $\{\phi^n : n = 0, 1, 2, . . . \}$ is orthogonal in $\mathbb{D}$?, and consider the problem of characterizing the univalent, full self-maps of $\mathbb{D}$ in terms of the norm of the composition operator induced. The first problem is analogous to a celebrated question asked by W. Rudin on the Hardy space setting that was answered recently ([3] and [15]). The second problem is analogous to a problem investigated by J. Shapiro in [14] about characterization of inner functions in the setting of $H^2$.Comment: 8 pages, 1 figure. See also http://webdelprofesor.ula.ve/nucleotachira/gchacon or http://webdelprofesor.ula.ve/humanidades/grchaco

When is Democracy an Equilibrium?: Theory and Evidence from Colombia's "La Violencia"

The conventional wisdom in political science is that for a democracy to be consolidated, all groups must have a chance to attain power. If they do not then they will subvert democracy and choose to fight for power. In this paper we show that this wisdom is seriously incomplete because it considers absolute, not relative payoffs. Although the probability of winning an election increases with the size of a group, so does the probability of winning a fight. Thus in a situation where all groups have a high chance of winning an election, they may also have a high chance of winning a fight. Indeed, in a natural model, we show that democracy may never be consolidated in such a situation. Rather, democracy may only be stable when one group is dominant. We provide a test of a key aspect of our model using data from "La Violencia", a political conflict in Colombia during the years 1946-1950 between the Liberal and Conservative parties. Consistent with our results, and contrary to the conventional wisdom, we show that fighting between the parties was more intense in municipalities where the support of the parties was more evenly balanced.

A study to solve the problem of the financially irresponsible motorist in Costa Rica

Thesis (M.B.A.)--Boston Universit

Uniaxial pressure dependence of magnetic order in MnSi

We report comprehensive small angle neutron scattering (SANS) measurements complemented by ac susceptibility data of the helical order, conical phase and skyrmion lattice phase (SLP) in MnSi under uniaxial pressures. For all crystallographic orientations uniaxial pressure favours the phase for which a spatial modulation of the magnetization is closest to the pressure axis. Uniaxial pressures as low as 1kbar applied perpendicular to the magnetic field axis enhance the skyrmion lattice phase substantially, whereas the skyrmion lattice phase is suppressed for pressure parallel to the field. Taken together we present quantitative microscopic information how strain couples to magnetic order in the chiral magnet MnSi.Comment: 23 pages, includes supplemen

A cross-linguistic database of phonetic transcription systems

Contrary to what non-practitioners might expect, the systems of phonetic notation used by linguists are highly idiosyncratic. Not only do various linguistic subfields disagree on the specific symbols they use to denote the speech sounds of languages, but also in large databases of sound inventories considerable variation can be found. Inspired by recent efforts to link cross-linguistic data with help of reference catalogues (Glottolog, Concepticon) across different resources, we present initial efforts to link different phonetic notation systems to a catalogue of speech sounds. This is achieved with the help of a database accompanied by a software framework that uses a limited but easily extendable set of non-binary feature values to allow for quick and convenient registration of different transcription systems, while at the same time linking to additional datasets with restricted inventories. Linking different transcription systems enables us to conveniently translate between different phonetic transcription systems, while linking sounds to databases allows users quick access to various kinds of metadata, including feature values, statistics on phoneme inventories, and information on prosody and sound classes. In order to prove the feasibility of this enterprise, we supplement an initial version of our cross-linguistic database of phonetic transcription systems (CLTS), which currently registers five transcription systems and links to fifteen datasets, as well as a web application, which permits users to conveniently test the power of the automatic translation across transcription systems