Testing a DSGE model and its partner database

There is now an impetus to apply dynamic stochastic general equilibrium models to forecasting. But these models typically rely on purpose-built data, for example on tradable and nontradable sector outputs. How then do we know that the model will forecast well, in advance? We develop an early warning test of the database-model match and apply that to a Colombian model. Our test reveals where the combination should work (consumption) and where not (in investment). The test can be adapted to look at many likely sources of DSGE model failure.Monetary Policy, Sectoral Model, DSGE, Forecast Performance, Kalman Filter. Classification JEL: F47; E01; C61

Specifically Adsorbed Ions in Hematite Flotation

Specifically adsorbed ions, such as calcium and magnesium in iron ore flotation, are ions that can chemically bind with the mineral surfaces and alter the surface properties. Calcium and magnesium are unavoidable in process water and their concentrations are increasing due to water recirculation and reagent additions. These ions are detrimental to the flotation process. Calcium has always been the main focus in research, yet we found that magnesium is more detrimental in flotation due to its smaller atomic size. Starch adsorption in iron ore flotation is key for the effective depression of hematite. It has been determined by flotation, zeta potential, and settling tests, that increasing calcium concentrations promote starch adsorption and reduce entrainment of hematite, whereas increasing magnesium concentrations greatly reduce the selectivity overall by promoting the adsorption of starch to everything in the slurry and resulting in lower selectivity

REVERSE CATIONIC FLOTATION OF HEMATITE

The reverse cationic flotation of hematite is the most common method to process hematite ores. The goal of this research is to understand the impact of fundamental water and surface effects to enable the optimization of the flotation process. At present, reverse cationic flotation is performed using a single chemical as both collector and frother. Excessive amounts of frother or collector should lead to diminished performance. This research investigates this phenomenon by replacing some of the collector with frothers. It was found that flotation recovery can be improved up to 2.5wt% via 10% replacement with methyl isobutyl carbinol (MIBC). Since most frothers are less expensive than the amine collector, there is a possibility of reducing cost of reagents and increasing profits in industry. There is a large body of literature on the impact of calcium on the flotation process. However, despite magnesium and calcium often being treated as interchangeable in literature and practice, magnesium’s smaller atomic size suggests that its behavior in flotation should be stronger. This research investigates the effect of calcium and magnesium in the adsorption of starch onto the hematite. We have found that initially both ions are beneficial to the process but as the magnesium concentrations increase, it becomes detrimental to flotation. These results make it clear that magnesium is not a one-for-one replacement of calcium in iron ore flotation, and should be accounted for and, if necessary, controlled separately. Lastly, the time it takes for the hematite to become fully hydrated may play a role in flotation. If the hydration of fresh surfaces takes place during the ½ to 2 hours that the xix hematite is expected to reside in the concentration process, then this could have a significant impact in flotation. In this research, the time scale of the hydration of pure hematite was determined to be on the order of 5 to 20 minutes, which tells us that in a plant-scale operation, it is very likely that the hematite is completely hydrated before it reaches flotation. These findings demonstrate improved understanding of reverse cationic flotation, which leads to a set of clear process recommendations

Analytical solution to DGLAP integro-differential equation in a simple toy-model with a fixed gauge coupling

We consider a simple model for QCD dynamics in which DGLAP integro-differential equation may be solved analytically. This is a gauge model which possesses dominant evolution of gauge boson (gluon) distribution and in which the gauge coupling does not run. This may be ${\cal N} =4$ supersymmetric gauge theory with softly broken supersymmetry, other finite supersymmetric gauge theory with lower level of supersymmetry, or topological Chern-Simons field theories. We maintain only one term in the splitting function of unintegrated gluon distribution and solve DGLAP analytically for this simplified splitting function. The solution is found by use of the Cauchy integral formula. The solution restricts form of the unintegrated gluon distribution as function of transfer momentum and of Bjorken $x$. Then we consider an almost realistic splitting function of unintegrated gluon distribution as an input to DGLAP equation and solve it by the same method which we have developed to solve DGLAP equation for the toy-model. We study a result obtained for the realistic gluon distribution and find a singular Bessel-like behaviour in the vicinity of the point $x=0$ and a smooth behaviour in the vicinity of the point $x=1.$Comment: 25 page

Sensibilidad del IPC a la Tasa de Cambio en Colombia: Una Medición de Largo Plazo

En el presente artículo se realiza una aproximación del pass-through de largo plazo de la tasa de cambio nominal al índice de precios al consumidor (IPC) para Colombia durante el período 1994 - 2005 siguiendo de cerca la propuesta de Campa y Goldberg (2006). En ella se tienen en cuenta algunas de las hipótesis desarrolladas recientemente por la macroeconomía internacional para explicar el enigma de la desconexión entre la tasa de cambio y la inflación doméstica, tales como la presencia de márgenes de distribución y comercialización sobre los bienes importados y el peso de estos en la canasta del IPC. El ejercicio permite identificar, partiendo de una estructura de mercado de competencia monopolística y empleando la información contenida en las matrices de insumo-producto del DANE varios canales a través de los cuales se da el traspaso de un choque de la tasa de cambio nominal al IPC. La calibración bajo el escenario base permite concluir que, en promedio, una devaluación nominal del 10% implica un incremento aproximado en el IPC del 2.82%. Adicionalmente, desde un punto de vista estático se observa que este efecto estimado no ha sido constante durante el período estudiado y contrario a la hipótesis de Taylor (2000) el pass-through ha aumentado en medio de una reducción de la inflación. En efecto, mientras que en 1994 el efecto era del 2.64%, en 2005 era de aproximadamente 2.91\% con un pico de 3.41% en 2003.Pass-Through, Transables, No Transables, Competencia Imperfecta, Matriz Insumo - Producto, Colombia. Classification JEL: E01; F3; F4; L1.

Drying/encapsulation of red wine to produce ingredientes for healthy foods

Epidemiological evidence indicates that moderate consumption of red wine reducesthe incidence of coronary disease, atherosclerosis, and platelet aggregation. Wine is very rich in antioxidant compounds because of their phenolic components.However, many people for ethnic, social or religious reasons do not consume wine. Drying/encapsulation of red wine in the presence of adequate carbohydrates leads to water and more than 99% of alcohol removal; a glassy amorphous microstructure is obtained in which the wine's phenolic compounds are entrapped. The resulting product is a free flowing powder which could be used for the polyphenol enrichment of healthy foods and/or drink powders, as well as in the pharmaceutical industry. The wine industry may take advantage of the dried/encapsulated red wine using as a raw material red wines which have littlecommercial value for different reasons; i.e. poor quality due to raw material, unfavourable climatic conditions, or wines that suffered some alteration during the wine making process. Dry encapsulated wine may be a new alternative to red wines that cannot be sold as such for different reasons, and open new opportunities to diversify wine products.Fil: Alvarez Gaona, Izmari Jasel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; ArgentinaFil: Rocha Parra, Diego Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; ArgentinaFil: Zamora, María Clara. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; ArgentinaFil: Chirife, Jorge. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; Argentin

Validation of the Scale of Emotional States in the Physical Education Context

The purpose of the present study was to validate an instrument of student emotional experiences in the Spanish Physical Education context. The sample of participants consisted of 864 secondary education students from various educational institutions of Spain who ranged in age from 13 to 19 years. To assess the psychometric properties of the Scale of Emotions in Physical Education (SEPE), various types of analyses were conducted. The factor structure of the SEPE was examined through confirmatory factorial analysis in relation to two models. In the first model, it was proposed that the eight first order factors, which represented the eight emotional states, would be correlated amongst each other. In the second model, an eight-factor model with two higher order factors was proposed, with these higher order factors representing distinct sets of positive and negative emotions. The results provide support the presence of an eight-factor second order model which consisted of sets of four positive emotions and four negative emotions. These results provide evidence for the reliability and validity of the SEPE within the Spanish Physical Education context

Adaptation and Validation of the Mind-Wandering Questionnaire (MWQ) in Physical Education Classes and Analysis of Its Role as Mediator between Teacher and Anxiety

Physical education (PE) classes are one of the primary means of adopting healthy lifestyles and contribute greatly to personal well-being. However, it is necessary that students pay attention and do not enter a mind-wandering state as this can be negative for the purposes of PE classes. Therefore, we adapted and validated the Mind-Wandering Questionnaire (MWQ) to the Spanish PE context and analyzed the influence of the teacher on this new variable. Two independent samples of high school students between the ages of 13 and 19 participated in the study. In order to assess the psychometric properties of the MWQ, various analyses were carried out. The results of the confirmatory factorial analysis (CFA) provided support for the structure of the questionnaire. The structure of the model was gender-invariant. The Cronbach alpha value was higher than 0.70 and showed an adequate level of temporal stability. In addition, we present a second study in which high school students between the ages of 13 and 19 participated, and which are independent of the first study. The analyses in this study were mainly based on structural equation modelling, and demonstrated the teacher’s influence on mind-wandering and showed that mind-wandering acted as a predictor of anxiety in high school students. The results of this study provided evidence of the reliability and validity of the MWQ in the Spanish PE context

The Influence of the Social Context on Motivation towards the Practice of Physical Activity and the Intention to be Physically Active

According toWHOdata, only around 20% of adolescents participate in physical activity (PA) during their free time. The social context can act as a support for adolescents to do PA, given the e ect that both parents, friends and teachers have on young people’s behaviour owing to the large amount of time and influence they have on them. Therefore, the aim of this study is to analyse the role of the social context on adolescents’ motivation to practise PA and their intention to be physically active. This study involved the participation of students in compulsory and post-compulsory secondary education. Several statistical analyses were performed, including three confirmatory factorial analyses of the scales and a structural equations model that explains the causal relationships between the variables. The results showed how support for autonomy in the social context positively predicts autonomous motivation, whereas the psychological control of the social context negatively predicts it. Autonomous motivation positively predicted intent, attitude, behavioural control and subjective norms, and consequently, the practice of physical activity. In short, the study showed how the three validated scales have adequate goodness-of-fit indices while the structural equations model demonstrated the influence of the social context on the student’s motivational processes and the adoption of active life habits