Measurement of the inclusive ttbar cross section in the LHC

This document presents recent results of inclusive top-quark pair production cross section measurements at 7 and 8 TeV. The results are obtained analyzing the data collected by the CMS and ATLAS detectors at the LHC accelerator. Studies are performed in the dilepton channel, where the smallest uncertainty is reached, with different approaches. The most precise results of both experiments are combined and confronted with the most precise theoretical calculation (NNLO-NNLL).Comment: Proceeding of TOP2014 7th International Workshop on Top Quark Physic

A strategy based instruction for teaching listening skills to fourth graders at fisher kids bilingual school

This study sought to determine to what extent is strategy-based instruction useful for improving 25 fourth graders’ listening skills at Fisher Kids Bilingual School. Bearing in mind the results obtained in the learning needs analysis applied to students at the beginning of the intervention as well as certain negative aspects that were observed in the methodology offered by the textbook for the development of this skill, a set of listening activities were designed based on the development of making notes, inferring and keywords strategies. To achieve this purpose, the students were trained for 6 weeks following the strategy based instruction model proposed by O "Malley and Chamot" s (1990), in order to help them to be more aware of their learning and able to apply different strategies that facilitate the understanding of the information. The findings indicated the effectiveness of the use of those strategies not only contribute to the improvement of students’ performance in listening skills, but also offer to teacher the possibility to adopt and adapt new approaches, strategies and teaching models that offer students more appropriate alternatives to learn and enhance their performance in listening skills. Key words: Strategy Based Instruction, listening skill, comprehension, metacognitive.MaestríaMagister en la Enseñanza del Ingle

Simplifying a hydrological ensemble prediction system with a backward greedy selection of members – Part 2: Generalization in time and space

An uncertainty cascade model applied to stream flow forecasting seeks to evaluate the different sources of uncertainty of the complex rainfall-runoff process. The current trend focuses on the combination of Meteorological Ensemble Prediction Systems (MEPS) and hydrological model(s). However, the number of members of such a HEPS may rapidly increase to a level that may not be operationally sustainable. This paper evaluates the generalization ability of a simplification scheme of a 800-member HEPS formed by the combination of 16 lumped rainfall-runoff models with the 50 perturbed members from the European Centre for Medium-range Weather Forecasts (ECMWF) EPS. Tests are made at two levels. At the local level, the transferability of the 9th day hydrological member selection for the other 8 forecast horizons exhibits an 82% success rate. The other evaluation is made at the regional or cluster level, the transferability from one catchment to another from within a cluster of watersheds also leads to a good performance (85% success rate), especially for forecast time horizons above 3 days and when the basins that formed the cluster presented themselves a good performance on an individual basis. Diversity, defined as hydrological model complementarity addressing different aspects of a forecast, was identified as the critical factor for proper selection applications

On circulant matrices and rational points of Artin Schreier's curves

Let $\mathbb F_q$ be a finite field with $q$ elements, where $q$ is an odd prime power. In this paper we associated circulant matrices and quadratic forms with curves of Artin-Schreier $y^q - y = x \cdot P(x) - \lambda,$ where $P(x)$ is a $\mathbb F_q$-linearized polynomial and $\lambda \in \mathbb F_q$. Our main results provide a characterization of the number of rational points in some extension $\mathbb F_{q^r}$ of $\mathbb F_q$. In the particular case, in the case when $P(x) = x^{q^i}-x$ we given a full description of the number of rational points in term of Legendre symbol and quadratic characters