1,049 research outputs found
A representation theorem for integral rigs and its applications to residuated lattices
We prove that every integral rig in Sets is (functorially) the rig of global
sections of a sheaf of really local integral rigs. We also show that this
representation result may be lifted to residuated integral rigs and then
restricted to varieties of these. In particular, as a corollary, we obtain a
representation theorem for pre-linear residuated join-semilattices in terms of
totally ordered fibers. The restriction of this result to the level of
MV-algebras coincides with the Dubuc-Poveda representation theorem.Comment: Manuscript submitted for publicatio
Reforming the urban water system in Santiago, Chile
In the late 1980s, Chile planned to privatize Santiago's sanitary works enterprise (EMOS) but instead reformed it under public ownership. It did so through a regulatory framework that mimicked the design of a concession with a private utility, setting tariffs that ensured at least a seven percent return on assets, creating a neutral regulator independent of ministry intervention, and giving EMOS the right to appeal the regulator's tariff decisions. This reform of Santiago's water system is often cited as a case of successful reform under public management. Comparing a comprehensive measure of welfare with a counterfactual example, the authors show surprisingly large gains from Santiago's reform, given the relatively good initial conditions. (The gains accrued largely to government and employees, but consumers benefited from improved service and coverage). Why did reform in Santiago improve water system performance, when similar reform attempts under public management in other countries failed? 1) Chile has a long tradition of private water rights, shaped by early recognition that water is a scarce and tradable private good. 2) The reformed regulatory framework was designed to attract private investors to the water system and to motivate them to operate efficiently and expand the system. 3) Chile's unique electoral institutions sustained this framework under state operation after democracy was restored. 4) Chile's strong bureaucratic norms and institutions (permitting little corruption), combined with Santiago's relatively low-cost water system, permitted prices that effectively increased quasi-rents for investing in the system while minimizing the risk of inefficiency or monopoly rents. The authors also address the question of why EMOS was reformed but not privatized, and what the costs of not privatizing were. The system was privatized in 1999, but the changes from privatization are likely to be less significant than those introduced in 1989-90.Decentralization,Water Conservation,Environmental Economics&Policies,Water and Industry,Water Supply and Systems,Water Supply and Sanitation Governance and Institutions,Water and Industry,Water Conservation,Environmental Economics&Policies,Town Water Supply and Sanitation
The Spin-Orbit Evolution of GJ 667C System: The Effect of Composition and Other Planet's Perturbations
Potentially habitable planets within the habitable zone of M-dwarfs are
affected by tidal interaction. We studied the tidal evolution in GJ 667C using
a numerical code we call TIDEV. We reviewed the problem of the dynamical
evolution focusing on the effects that a rheological treatment, different
compositions and the inclusion of orbital perturbations, have on the spin-down
time and the probability to be trapped in a low spin-orbit resonance.
Composition have a strong effect on the spin-down time, changing, in some
cases, by almost a factor of 2 with respect to the value estimated for a
reference Earth-like model. We calculated the time to reach a low resonance
value (3:2) for the configuration of 6 planets. Capture probabilities are
affected when assuming different compositions and eccentricities variations. We
chose planets b and c to evaluate the probabilities of capture in resonances
below 5:2 for two compositions: Earth-like and Waterworld planets. We found
that perturbations, although having a secular effect on eccentricities, have a
low impact on capture probabilities and noth- ing on spin-down times. The
implications of the eccentricity variations and actual habitability of the GJ
667C system are discussed.Comment: 15 pages, 9 figures, 4 tables. Accepted for publication in MNRAS - V
Induction of stimulative parthenocarpy in Vitis vinifera L.
Stimulative parthenocarpy was induced in two varieties of Vitis vinifera L. Flame Tokay and Rose Muscat (local variety) out of eight varieties studied.In F l a m e T o k a y the delay or inhibition of bhe abscission of the calyptra and parthenocarpic development of the berries, was obtained with pre-bloom treatments (3 days before beginning of bloom) of 4CPA 30 ppm + KGA3 30 ppm. Induction and growth ,of parthenocarpic berries was most pronounced after post-bloom sprays (7 days after the end of bloom) with BA 1500 ppm + KGA3 80 ppm or 4CPA 30 ppm. A parthenocarpic development of the berries was also obtained with postbloom treatments of KGA3 at concentrations of 50 to 100 ppm. BA (Benzyladenine) alone had only a slight effect on the development of parthenocarpic berries. However, the results were surprisingly satisfactory when applied in combination with gibberellin (KGA3 80 ppm) or auxins. Treatments at bloom or after bloom with BA 800 ppm + KGA3 80 ppm increased bhe number of berries and cluster weight. Applications of BA 800 ppm + KGA3 80 ppm to Rose Musca t at the beginning of bloom resulted in clusters with practically all berries seedless. The artificially accelerated growth of the berries may provoke abortion of all the recently fecundated ovules and the non viability of the not fecundated ones. Clusters of the treated plants with an average of 520 flowers originated 501 parbhenocarpic berries (96%), whereas the control with an average 635 flowers per cluster gave a percentage of seeded + seedless berries of 14% only {95 berries per cluster). BA applied with auxin or gibberellin-like substances in full-bloom or after bloom produced seedless berries, which were smaller in size than the seeded berries of unsprayed clusters
Elastic Registration of Geodesic Vascular Graphs
Vascular graphs can embed a number of high-level features, from morphological
parameters, to functional biomarkers, and represent an invaluable tool for
longitudinal and cross-sectional clinical inference. This, however, is only
feasible when graphs are co-registered together, allowing coherent multiple
comparisons. The robust registration of vascular topologies stands therefore as
key enabling technology for group-wise analyses. In this work, we present an
end-to-end vascular graph registration approach, that aligns networks with
non-linear geometries and topological deformations, by introducing a novel
overconnected geodesic vascular graph formulation, and without enforcing any
anatomical prior constraint. The 3D elastic graph registration is then
performed with state-of-the-art graph matching methods used in computer vision.
Promising results of vascular matching are found using graphs from synthetic
and real angiographies. Observations and future designs are discussed towards
potential clinical applications
Propuesta curricular para el área de educación ambiental en colegios de secundaria del sur del Valle y norte del Cauca
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