A Methodology to Engineer and Validate Dynamic Multi-level Multi-agent Based Simulations

This article proposes a methodology to model and simulate complex systems, based on IRM4MLS, a generic agent-based meta-model able to deal with multi-level systems. This methodology permits the engineering of dynamic multi-level agent-based models, to represent complex systems over several scales and domains of interest. Its goal is to simulate a phenomenon using dynamically the lightest representation to save computer resources without loss of information. This methodology is based on two mechanisms: (1) the activation or deactivation of agents representing different domain parts of the same phenomenon and (2) the aggregation or disaggregation of agents representing the same phenomenon at different scales.Comment: Presented at 3th International Workshop on Multi-Agent Based Simulation, Valencia, Spain, 5th June 201

The N=1 superstring as a topological field theory

By "untwisting" the construction of Berkovits and Vafa, one can see that the N=1 superstring contains a topological twisted N=2 algebra, with central charge c^ = 2. We discuss to what extent the superstring is actually a topological theory.Comment: 8 Pages (LaTeX). TAUP-2155-9

Spatial Variation in Throughfall, Soil, and Plant Water Isotopes in a Temperate Forest

Studies of stable isotopes of water in the environment have been fundamental to advancing our understanding of how water moves through the soil‐plant‐atmosphere continuum; however, much of this research focuses on how water isotopes vary in time, rather than in space. We examined the spatial variation in the δ18O and δ2H of throughfall and bulk soil water, as well as branch xylem and bulk leaf water of Picea abies (Norway Spruce) and Fagus sylvatica (Beech), in a 1 ha forest plot in the northern Alps of Switzerland. Means and ranges of water isotope ratios varied considerably among throughfall, soil, and xylem samples. Soil water isotope ratios were often poorly explained by soil characteristics and often not predictable from proximal samples. Branch xylem water isotope values varied less than either soil water or bulk leaf water. The isotopic range observed within an individual tree crown was often similar to that observed among different crowns. As a result of the heterogeneity in isotope ratios, inferences about the depth of plant root water uptake drawn from a two end‐member mixing model were highly sensitive to the soil sampling location. Our results clearly demonstrate that studies using water isotopes to infer root water uptake must explicitly consider how to characterize soil water, incorporating measures of both vertical and lateral variation. By accounting for this spatial variation and the processes that shape it, we can improve the application of water isotopes to studies of plant ecophysiology, ecohydrology, soil hydrology, and paleoclimatology

Deformations of Lie Algebras using σ\sigma-derivations

In this article we develop an approach to deformations of the Witt and Virasoro algebras based on $\sigma$-derivations. We show that $\sigma$-twisted Jacobi type identity holds for generators of such deformations. For the $\sigma$-twisted generalization of Lie algebras modeled by this construction, we develop a theory of central extensions. We show that our approach can be used to construct new deformations of Lie algebras and their central extensions, which in particular include naturally the $q$-deformations of the Witt and Virasoro algebras associated to $q$-difference operators, providing also corresponding q-deformed Jacobi identities.Comment: 52 page

WFC3 Calibration and Data Processing

Wide Field Camera 3 (WFC3), a panchromatic imager being developed for the Hubble Space Telescope (HST), is now fully integrated and over the past year has completed first rounds of extensive ground testing at Goddard Space Flight Center (GSFC), in both ambient and thermal-vacuum test environments. This report summarizes the results of those tests and describes the pipeline processing methods that will be used to calibrate WFC3 data. WFC3 is designed to ensure that the superb imaging performance of HST is maintained through the end of the mission and takes advantage of recent developments in detector technology to provide new and unique capabilities for HST. WFC3 contains ultraviolet/visible (UVIS) and near-infrared (IR) imaging channels, offering high sensitivity and wide field of view over the broadest wavelength range of any HST instrument. It is slated to replace the current Wide Field and Planetary Camera 2 during Servicing Mission 4. The WFC3 UVIS channel is based on elements from the Advanced Camera for Surveys (ACS)Wide Field Camera (WFC), with a 4096x4096 pixel Marconi CCD covering a 160x160 arcsecond field of view. The WFC3 UVIS channel is optimized for maximum sensitivity in the near-UV and contains a complement of 48 spectral filters and a grism. The WFC3 IR channel uses a 1024x1024 pixel HgCdTe Hawaii-1R detector array covering a 135x135 arcsecond field of view. The array sensitivity is optimized in the 0.8-1.7micron spectral range. The IR channel accomodates 15 filters and 2 grisms for slitless spectroscopy

Síntesis, estudio teórico de aril-lactonas y evaluación de su actividad inhibidora de la formación de β-hematina y de la enzima β-lactamasa

Las enfermedades infecciosas se han convertido en un problema de salud pública debido a la emergencia de la resistencia microbiana. Más de cinco millones de personas en Colombia viven en regiones endémicas de malaria cuyo parásito es resistente a cloroquina. Microorganismos como S. aureus y Enterococcus spp., han desarrollado la enzima βlactamasa que los hace resistentes a antibióticos. Se sintetizaron cuatro α,γ-aril-lactonas, las cuales fueron evaluadas como inhibidoras de formación de β-hematina a 2 mg/mL . La reacción se realizó a 60 °C por 1 h a pH 4,0 y el complejo fue monitoreado a 386 nm . Las lactonas también fueron evaluadas como inhibidoras de la enzima β-lactamasa, a concentraciones de 5,4 µmol/L para los inhibidores y 36 a 108 µmol/L para amoxicilina como sustrato. La actividad enzimática de los compuestos se monitoreó a 250 nm, 37 ºC por 10 h a pH 7,3. La modelación de los complejos lactona-Fe porfirínico de la hemina mostró que la interacción se establece a través del oxígeno del anillo furano, pero cuando la lactona tiene un grupo α-piridinil, la interacción se favorece a través del nitrógeno con detrimento de la actividad inhibidora. En la modelación molecular de los complejos enzimáticos se muestra que los residuos del sitio activo responsables de la interacción con la lactona son la Serina64 y Tirosina150 a través de fuertes enlaces de hidrógeno entre los hidroxilos de estos residuos y el oxígeno carbonílico de la lactona

Infuence of the year and HMW glutenin subunits on end-use quality predictors if bread wheat waxy lines

The effects of environment and the high molecular weight glutenins on some quality properties (sedimentation volume, % protein content, and starch pasting viscosity) of bread wheat mutant waxy lines were evaluated. Thirty-eight 100% amylose-free F 2 derived F 6 and F 7 lines were used. The results indicated that the environment did not influence sedimentation volume, mixograph parameters and starch viscosity parameters of waxy flour. Variation in the % protein content was determined mainly by the environment. The sedimentation volume and the mixograph peak development time were influenced by the variation at over expression of Bx7 and the mixograph peak development time was influenced by the Glu-D1 locus. One starch viscosity parameter, time to peak viscosity, was influenced by variation at the Glu-A1 locus. This parameter is significantly lower in the waxy lines than the parent line, which shows the influence of the waxy loci. No significant correlation was observed for sedimentation volume, mixograph parameters, protein content and viscosity parameters of waxy line

A simple method for estimating relative risk using logistic regression

<p>Abstract</p> <p>Background</p> <p>Odds ratios (OR) significantly overestimate associations between risk factors and common outcomes. The estimation of relative risks (RR) or prevalence ratios (PR) has represented a statistical challenge in multivariate analysis and, furthermore, some researchers do not have access to the available methods. Objective: To propose and evaluate a new method for estimating RR and PR by logistic regression.</p> <p>Methods</p> <p>A provisional database was designed in which events were duplicated but identified as non-events. After, a logistic regression was performed and effect measures were calculated, which were considered RR estimations. This method was compared with binomial regression, Cox regression with robust variance and ordinary logistic regression in analyses with three outcomes of different frequencies.</p> <p>Results</p> <p>ORs estimated by ordinary logistic regression progressively overestimated RRs as the outcome frequency increased. RRs estimated by Cox regression and the method proposed in this article were similar to those estimated by binomial regression for every outcome. However, confidence intervals were wider with the proposed method.</p> <p>Conclusion</p> <p>This simple tool could be useful for calculating the effect of risk factors and the impact of health interventions in developing countries when other statistical strategies are not available.</p

Comunicar ciencia en México. Discursos y espacios sociales

La generación y divulgación de la ciencia y la tecnología es una tarea que implica contribuir al desarrollo de una cultura que vaya más allá del registro y difusión de los hechos y nombres científicos, al suponer la comprensión crítica de la labor propia como proceso socialmente contextualizado, enraizado en factores históricos, políticos, económicos y éticos. Los trabajos aquí presentados proponen asumir que la comunicación pública del conocimiento expresa también las controversias socio–científicas y la relación social de ciencia y tecnología en las condiciones imperantes de transición vertiginosa en la producción cultural, científica y tecnológica.ITESO, A.C.Consejo de Ciencia y Tecnología del Estado de Jalisc