ESTIMATION OF INCOME DISTRIBUTION AND DETECTION OF SUBPOPULATIONS: AN EXPLANATORY MODEL

Inequality and polarization analyses are complementary but conceptually different. They are usually implemented independently in practic e, with different a priori assumptions and different tools. In this paper, we develop a unique method to study simultaneously these different and complementary concerns. Based on mixture models, the method we develop includes at the same time : an estimation of income distribution with no a priori assumptions - a decomposition in several homogeneous subpopulations - an explanatory model to study the structure of the income distribution.

Nondiagonal CPmCP_m Coset Models and their Poincar\'E Polynomials

$N=2$ coset models of the type $SU(m+1)/SU(m)\times U(1)$ with nondiagonal modular invariants for both $SU(m+1)$ and $SU(m)$ are considered. Poincar\'e polynomials of the corresponding chiral rings of these algebras are constructed. They are used to compute the number of chiral generations of the associated string compactifications. Moddings by discrete symmetries are also discussed.Comment: 22 pages, (RevTex), preprint GTCRG-92-1 and CNEA-CAB-039/92. % Minor changes in the result

La ecología en tensión. Una indagación histórica del presente de la disciplina

Desde que la ecología surgió como ciencia, las ideas y conceptos que la estructuran han sufrido numerosos cambios que presentan tanto rupturas como continuidades. Es por esto que creemos que la situación actual de la disciplina se comprenderá de forma más acabada si se la contempla desde su proceso histórico. En este trabajo esbozaremos la historia de las ideas ecológicas, exponiendo las características de los principales debates en torno de conceptos tan importante como sucesión vegetal, nicho, competencia y comunidad, a fin de reconocer tanto los aspectos incipientes como aquellos heredados en los debates que parecen inaugurarse en los últimos años.Since Ecology was born as science, ecological ideas and concepts underwent though numerous changes with ruptures and continuities. Therefore, in aims of a better understanding of the discipline in the present, we consider necessary to comprehend its historical processes. In this study we offer a revision on the history of the ideas in Ecology and a review on the characteristic of the most important debates behind key concepts such a plant succession, niche, competition and community, with the aim of recognize new and inherited aspects in current ecological debates

Effects of Elevated CO2 Concentrations and Elevated Temperatures on Isoprene Emissions of Rhamnus cathartica (European buckthorn), Quercus rubra (red oak) and Quercus michauxii (swamp chestnut oak)

Tropospheric ozone is a ground-level pollutant and is produced from primary air pollutants like nitrogen oxides and volatile organic compounds (VOCs). While many VOCs are anthropogenic, isoprene is emitted from certain species of plants and reacts with nitrogen oxides to form ozone. Previous studies have found that isoprene can be suppressed by CO2, but such suppression can be reduced under conditions of increased temperature. However, this pattern is not seen in all plants capable of emitting isoprene. The focus of this is study is to determine if similar patterns are present in the invasive tree species of buckthorn (Rhamnus cathartica) and two oak species – red oak (Quercus rubra) and swamp chestnut oak (Quercus michauxii) – that are native in Chicago, Illinois. Two hypotheses being tested are patterns of isoprene suppression by CO2 at ambient temperature in Q. michauxii will be the same as the patterns seen in Q. rubra (H1) and patterns of isoprene suppression by CO2 at ambient temperature in R. cathartica will be the same as the patterns seen in Q. rubra. (H2). This study also tests the hypothesis that isoprene suppression by CO2 at elevated temperature will be reduced in R. cathartica, leading to poorer air quality in Chicago, IL. (H3). To test these hypotheses, individuals of the native species were grown in a greenhouse and the buckthorn species was sampled from a field and brought into the greenhouse. CO2 concentrations (400 ppm and 800 ppm) and temperatures (30 °C and 35 °C) were adjusted for the leaves using a leaf gas exchange system; isoprene was collected and measured concurrently with a gas chromatograph. Results show that patterns of isoprene suppression were not the same as those seen in Q. rubra for R. cathartica nor Q.michauxii, thus rejecting H1 and H2. Isoprene suppression was not observed for R. cathartica, even when CO2 was increased. Thus, even in conditions where CO2 emissions increase, isoprene will also increase and thus support H3. These findings will help further understand the potential effects that different plant species, whether invasive or native, can have on air quality

Ayudas de Estado y Código Comunitario de conducta fiscal

Texto de la conferencia pronunciada el día 13 de enero de 1999 en la Facultad de Derecho de la Universidad Pública de Navarra

A short note on the nested-sweep polarized traces method for the 2D Helmholtz equation

We present a variant of the solver in Zepeda-N\'u\~nez and Demanet (2014), for the 2D high-frequency Helmholtz equation in heterogeneous acoustic media. By changing the domain decomposition from a layered to a grid-like partition, this variant yields improved asymptotic online and offline runtimes and a lower memory footprint. The solver has online parallel complexity that scales \emph{sub linearly} as $\mathcal{O} \left( \frac{N}{P} \right)$, where $N$ is the number of volume unknowns, and $P$ is the number of processors, provided that $P = \mathcal{O}(N^{1/5})$. The variant in Zepeda-N\'u\~nez and Demanet (2014) only afforded $P = \mathcal{O}(N^{1/8})$. Algorithmic scalability is a prime requirement for wave simulation in regimes of interest for geophysical imaging.Comment: 5 pages, 5 figure