New Keynesian Model Features that Can Reproduce Lead, Lag and Persistence Patterns

This paper uses a new method for describing dynamic comovement and persistence in economic time series which builds on the contemporaneous forecast error method developed in den Haan (2000). This data description method is then used to address issues in New Keynesian model performance in two ways. First, well known data patterns, such as output and inflation leads and lags and inflation persistence, are decomposed into forecast horizon components to give a more complete description of the data patterns. These results show that the well known lead and lag patterns between output and inflation arise mostly in the medium term forecasts horizons. Second, the data summary method is used to investigate a rich New Keynesian model with many modeling features to see which of these features can reproduce lead, lag and persistence patterns seen in the data. Many studies have suggested that a backward looking component in the Phillips curve is needed to match the data, but our simulations show this is not necessary. We show that a simple general equilibrium model with persistent IS curve shocks and persistent supply shocks can reproduce the lead, lag and persistence patterns seen in the data.

Depletion of the heaviest stable N isotope is associated with NH4 +/NH3 toxicity in NH4 +-fed plants

Background: In plants, nitrate (NO(3)(-)) nutrition gives rise to a natural N isotopic signature (delta(15)N), which correlates with the delta(15)N of the N source. However, little is known about the relationship between the delta(15)N of the N source and the (14)N/(15)N fractionation in plants under ammonium (NH(4)(+)) nutrition. When NH(4)(+) is the major N source, the two forms, NH(4)(+) and NH(3), are present in the nutrient solution. There is a 1.025 thermodynamic isotope effect between NH(3) (g) and NH(4)(+)(aq) which drives to a different delta(15)N. Nine plant species with different NH(4)(+)-sensitivities were cultured hydroponically with NO(3)(-) or NH(4)(+) as the sole N sources, and plant growth and delta(15)N were determined. Short-term NH(4)(+)/NH(3) uptake experiments at pH 6.0 and 9.0 (which favours NH(3) form) were carried out in order to support and substantiate our hypothesis. N source fractionation throughout the whole plant was interpreted on the basis of the relative transport of NH(4)(+) and NH(3). -- Results: Several NO(3)(-)-fed plants were consistently enriched in (15)N, whereas plants under NH(4)(+) nutrition were depleted of (15)N. It was shown that more sensitive plants to NH(4)(+) toxicity were the most depleted in (15)N. In parallel, N-deficient pea and spinach plants fed with (15)NH(4)(+) showed an increased level of NH(3) uptake at alkaline pH that was related to the (15)N depletion of the plant. Tolerant to NH(4)(+) pea plants or sensitive spinach plants showed similar trend on (15)N depletion while slight differences in the time kinetics were observed during the initial stages. The use of RbNO(3) as control discarded that the differences observed arise from pH detrimental effects. -- Conclusions: This article proposes that the negative values of delta(15)N in NH(4)(+)-fed plants are originated from NH(3) uptake by plants. Moreover, this depletion of the heavier N isotope is proportional to the NH(4)(+)/NH(3) toxicity in plants species. Therefore, we hypothesise that the low affinity transport system for NH(4)(+) may have two components: one that transports N in the molecular form and is associated with fractionation and another that transports N in the ionic form and is not associated with fractionation.

Optimización del Lead Time de vehículos mediante la implementación de una solución RTLS (Real Time Location System)

A lo largo de este documento, se va a explicar la implantación del proyecto que he realizado basado en la localización de vehículos en la fábrica de Mercedes Benz España situada en Vitoria-Gasteiz. Durante la realización de este proyecto, se han llevado a cabo diversos estudios con el fin de conseguir la correcta implantación de las tecnologías empleadas. Se han realizado diferentes alternativas de posicionamiento de los componentes y diversas pruebas para comprobar el correcto funcionamiento de la solución. La solución del proyecto se realizará en distintas fases. La primera de ellas tratará sobre el estudio en una determinada zona de la fábrica, más concretamente la denominada “Área Técnica”, en esta zona se encuentran los vehículos que sufren algún retoque una vez están montados, esta zona se utilizará como piloto para una vez finalizado y comprobado su éxito ampliar la solución al resto de zonas. Previamente a mi incorporación se realizó un estudio para la colocación de los elementos necesarios en esta zona y se ha visto las posibilidades y beneficios que aportaría el control de los vehículos dentro de la fábrica. La siguiente fase será implantar la solución en el resto de las áreas que se encuentran dentro de la fábrica de Vitoria-Gasteiz así como la instalación de unos dispositivos que estarán ubicados en las puertas. Estos ayudarán a mejorar la ubicación de los vehículos ya que podremos conocer si los vehículos se encuentran dentro o fuera de la fábrica. Finalmente se ha realizado la integración de la solución en los sistemas actuales que utilizan en la fábrica para la gestión de los vehículos durante su ciclo de vida.