21,615 research outputs found
Characterization of the atmospheric depth profile using the ground-level temperature: The case of MalargĂĽe, Argentina
We present a study of the atmospheric depth profile and the dependence with its characteristic parameters. We introduce a new model, named GAMMA, based on a parameterization that allows us to obtain the atmospheric depth profile specifying only one simple physical parameter, namely the temperature at ground. The GAMMA model consists of a multilayer representation of the atmosphere that can be adjusted conveniently via constrained fits that are built to ensure interlayer continuity for both atmospheric depth and density profiles. Our analysis uses experimental data collected at MalargĂĽe, Argentina by meteorological radiosondes. The GAMMA model can reproduce the averaged atmospheric depth profiles in all the cases available for analysis with good accuracy. The relative differences between model predictions and averaged data are always less than approximately 0.7%.Fil: Moreno, Juan Cruz. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de FĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de FĂsica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de FĂsica; ArgentinaFil: Sciutto, Sergio Juan. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de FĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de FĂsica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de FĂsica; Argentin
Beyond Stemming and Lemmatization: Ultra-stemming to Improve Automatic Text Summarization
In Automatic Text Summarization, preprocessing is an important phase to
reduce the space of textual representation. Classically, stemming and
lemmatization have been widely used for normalizing words. However, even using
normalization on large texts, the curse of dimensionality can disturb the
performance of summarizers. This paper describes a new method for normalization
of words to further reduce the space of representation. We propose to reduce
each word to its initial letters, as a form of Ultra-stemming. The results show
that Ultra-stemming not only preserve the content of summaries produced by this
representation, but often the performances of the systems can be dramatically
improved. Summaries on trilingual corpora were evaluated automatically with
Fresa. Results confirm an increase in the performance, regardless of summarizer
system used.Comment: 22 pages, 12 figures, 9 table
Coalition-proof supply function equilibria in oligopoly
In an industry where firms compete via supply functions, the set of equilibrium outcomes is large. If decreasing supply functions are ruled out, this set is reduced significantly, but remains large. Specifically, the set of prices that can be sustained by supply function equilibria is the interval between the competitive price and the Cournot price. In sharp contrast, when the number of firms is above a threshold we identify (e.g., three if demand is linear), only the Cournot outcome can be sustained by a coalition-proof supply function equilibrium.Publicad
Logarithmic Relaxation in a Kinetically Constrained Model
We present Monte Carlo simulations in a modification of the
north-or-east-or-front model recently investigated by Berthier and Garrahan [J.
Phys. Chem. B 109, 3578 (2005)]. In this coarse-grained model for relaxation in
supercooled liquids, the liquid structure is substituted by a three-dimensional
array of cells. A spin variable is assigned to each cell, with values 0 or 1
denoting respectively unexcited and excited local states in a mobility field.
Change in local mobility (spin flip) for a given cell is permitted according to
kinetic constraints determined by the mobilities of neighboring cells. In this
work we keep the same kinetic constraints of the original model, but we
introduce two types of cells (denoted as "fast'' and "slow'') with very
different rates for spin flip. As a consequence, fast and slow cells exhibit
very different relaxation times for spin correlators. While slow cells exhibit
standard relaxation, fast cells display anomalous relaxation, characterized by
a concave-to-convex crossover in spin correlators by changing temperature or
composition. At intermediate state points logarithmic relaxation is observed
over three time decades. These results display striking analogies with dynamic
correlators reported in recent simulations on a bead-spring model for polymer
blends.Comment: Major changes. To be published in Journal of Chemical Physic
A coalitional procedure leading to a family of bankruptcy rules
We provide a general coalitional procedure that characterizes a family of rules for bankruptcy problems inspired by the Talmud.bankruptcy, coalitions, claims, Talmud.
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