943 resultados para Relativistic processes


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Conocer en qué medida el grado de dominio de la L2 configura el tiempo asignado a los procesos de escritura y su distribución en el transcurso de la composición. 21 aprendices de inglés como lengua extranjera divididos en tres niveles de dominio: pre-intermedio (N1), intermedio (N2) y avanzado (N3), estando integrado cada grupo por 7 sujetos de tercero de BUP, tercero de Magisterio de Lenguas Extranjeras y recién licenciados en Filología Inglesa respectivamente. Cada sujeto de la muestra realizó una composición argumentada en L1 y L2 siguiendo la técnica del pensamiento en voz alta en dos sesiones distintas y recibiendo entrenamiento previo en la técnica de pensar en voz alta. La tarea en L2 se llevó a cabo antes de la de L1 para tratar de evitar la traducción dada la similitud de los temas propuestos, idénticos para todos los sujetos. Al finalizar los sujetos rellenaron un cuestionario restrospectivo. Se grabaron y transcribieron las sesiones. Oxford Placement Test, prueba que se centra en la discriminación de habilidades gramaticales de lectura y de comprensión auditiva. Análisis de la distribución temporal de los procesos de planificación y formulación en composiciones argumentales en L1 y L2. ANOVA. Los sujetos de la muestra dedicaron un porcentaje similar de tiempo a formular globalmente sus textos en L1 y L2, sin embargo, la proporción de procesos de formulación fluída frente a los de naturaleza problemática varían según la lengua: en L1 la proporción en de 5/1 y en L2 de 2/1. A medida que aumenta la habilidad del escritor se observa una tendencia a asumir progresivamente el papel de escritor como controlador del proceso, en detrimento del escritor como productor de un texto. Los resultados de la investigación apuntan a que no puede considerarse que el proceso de composición sea lineal, aunque sea incorrecto pensar que el escritor va a dedicar idénticos recursos temporales al mismo proceso en todas las partes de la composición (planificación, formulación y revisión). Existe un punto intermedio entre los dos extremos: ciertos procesos tienen más probabilidad de ser activados en ciertos momentos que otros y, como consecuencia, su probabilidad de ocurrencia cambia a medida que se avanza en el transcurso de la tarea.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Resumen tomado de la publicación

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Resumen tomado de la publicaci??n

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Here we discuss two consecutive MERLIN observations of the X-ray binary LS I +61° 303 . The first observation shows a double-sided jet extending up to about 200 AU on both sides of a central source. The jet shows a bent S-shaped structure similar to the one displayed by the well-known precessing jet of SS 433 . The precession suggested in the first MERLIN image becomes evident in the second one, showing a one-sided bent jet significantly rotated with respect to the jet of the day before. We conclude that the derived precession of the relativistic (beta=0.6) jet explains puzzling previous VLBI results. Moreover, the fact that the precession is fast could be the explanation of the never understood short term (days) variability of the associated gamma-ray source 2CG 135+01 / 3EG J0241+6103

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In the last decades, the awareness of environmental issues has increased in society considerably. There is an increasing need to improve the effluent quality of domestic wastewater treatment processes. This thesis describes the application of the Sequencing Batch Reactor (SBR) technology for Biological Nutrient Removal (BNR) from the wastewater. In particular, the work presented evolves from the nitrogen removal to the biological nutrient removal (i.e. nitrogen plus phosphorous removal) with special attention to the operational strategy design, the identification of possible reactor cycle controls or the influent composition related to the process efficiency. In such sense, also the use of ethanol as an external carbon (when low influent Carbon:Phosphorus (C:P) or Carbon:Nitrogen (C:N) ratios are presented) are studied as an alternative to maintain the BNR efficiency.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The chemical contamination of natural waters is a global problem with a worldwide impact. Considering the relevance of this problem, this thesis is intended, on one hand, to develop different separation/preconcentration techniques based on membranes ability to permeate anions for the transport of toxic oxyanions of chromium(VI) and arsenic contained in aqueous matrices. In particular, we have investigated supported liquid membranes and polymer inclusion membranes, both of which contain the commercial quaternary ammonium salt Aliquat 336 as a carrier, as well as commercial anion exchange membranes. On the other hand, we have focused on the development of chemical sensors to facilitate the monitoring of several metals from different aqueous matrices. Thus, a selective optical sensor for Cr(VI) based on polymeric membranes containing Aliquat 336 as an ionophore has been designed. Additionally, mercury-based screen-printed electrodes have been evaluated for for cadmium, lead, copper and zinc detection.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

La millora de la productivitat i la qualitat són indubtablement dues de les principals exigències del sector productiu modern i factors clau per la competitivitat i la supervivència. Dins aquest sector,la fabricació per arrancada de material juga encara avui en dia un paper protagonista tot i l'aparició de noves tècniques de conformat per addició.Indústries com l'aeronàutica, l'automobilística,la del motlle o l'energètica, depenen en bona part de les prestacions de les màquines-eina. Aquesta Tesi aborda dos aspectes rellevants quan es tracta de millorar de la productivitat i la qualitat del sector productiu: el problema del fimbrament, més conegut per la denominació anglosaxona chatter,i la monitorització de la rugositat superficial en el mecanitzat a alta velocitat.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Brundtland Report (WCED, 1987) best known for its popularisation of the concept of sustainable development, also made recommendations for a new approach to design and production, setting out terms for: ‘a production system that respects... the ecological base’ and ‘a technological system that searches continuously for new solutions’. The industrial production, consumption and waste treatment of products today causes a large amount of various environmental burdens. The development and design of new products with reduced environmental impact is one of the new challenges towards a more sustainable society and is therefore an important task in the near future.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This project investigates the effectiveness and feasibility of scaling-up an eco-bio-social approach for implementing an integrated community-based approach for dengue prevention in comparison with existing insecticide-based and emerging biolarvicide-based programs in an endemic setting in Machala, Ecuador.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A case of long-range transport of a biomass burning plume from Alaska to Europe is analyzed using a Lagrangian approach. This plume was sampled several times in the free troposphere over North America, the North Atlantic and Europe by three different aircraft during the IGAC Lagrangian 2K4 experiment which was part of the ICARTT/ITOP measurement intensive in summer 2004. Measurements in the plume showed enhanced values of CO, VOCs and NOy, mainly in form of PAN. Observed O3 levels increased by 17 ppbv over 5 days. A photochemical trajectory model, CiTTyCAT, was used to examine processes responsible for the chemical evolution of the plume. The model was initialized with upwind data and compared with downwind measurements. The influence of high aerosol loading on photolysis rates in the plume was investigated using in situ aerosol measurements in the plume and lidar retrievals of optical depth as input into a photolysis code (Fast-J), run in the model. Significant impacts on photochemistry are found with a decrease of 18% in O3 production and 24% in O3 destruction over 5 days when including aerosols. The plume is found to be chemically active with large O3 increases attributed primarily to PAN decomposition during descent of the plume toward Europe. The predicted O3 changes are very dependent on temperature changes during transport and also on water vapor levels in the lower troposphere which can lead to O3 destruction. Simulation of mixing/dilution was necessary to reproduce observed pollutant levels in the plume. Mixing was simulated using background concentrations from measurements in air masses in close proximity to the plume, and mixing timescales (averaging 6.25 days) were derived from CO changes. Observed and simulated O3/CO correlations in the plume were also compared in order to evaluate the photochemistry in the model. Observed slopes change from negative to positive over 5 days. This change, which can be attributed largely to photochemistry, is well reproduced by multiple model runs even if slope values are slightly underestimated suggesting a small underestimation in modeled photochemical O3 production. The possible impact of this biomass burning plume on O3 levels in the European boundary layer was also examined by running the model for a further 5 days and comparing with data collected at surface sites, such as Jungfraujoch, which showed small O3 increases and elevated CO levels. The model predicts significant changes in O3 over the entire 10 day period due to photochemistry but the signal is largely lost because of the effects of dilution. However, measurements in several other BB plumes over Europe show that O3 impact of Alaskan fires can be potentially significant over Europe.