Demand shocks and trade balance dynamics

This paper studies the current account dynamics in the G-7 countries plus Spain. We estimate a SVAR model which allows us to identify three different shocks: supply shocks, real demand shocks and nominal shocks. We use a different identification procedure from previous work based on a microfounded stochastic open-economy model in which the real exchange rate is a determinant of the Phillips curve. Estimates from a structural VAR show that real demand shocks explain most of the variability of current account imbalances, whereas, contrary to previous findings, nominal shocks play no role. The results we obtain are consistent with the predictions of a widely set of open-economy models and illustrate that demand policies are the main responsible of trade imbalances.Current account, SVAR

Revisiting the luminosity function of single halo white dwarfs

White dwarfs are the fossils left by the evolution of low-and intermediate-mass stars, and have very long evolutionary timescales. This allows us to use them to explore the properties of old populations, like the Galactic halo. We present a population synthesis study of the luminosity function of halo white dwarfs, aimed at investigating which information can be derived from the currently available observed data. We employ an up-to-date population synthesis code based on Monte Carlo techniques, that incorporates the most recent and reliable cooling sequences for metal poor progenitors as well as an accurate modeling of the observational biases. We find that because the observed sample of halo white dwarfs is restricted to the brightest stars only the hot branch of the white dwarf luminosity function can be used for such purposes, and that its shape function is almost insensitive to the most relevant inputs, like the adopted cooling sequences, the initial mass function, the density profile of the stellar spheroid, or the adopted fraction of unresolved binaries. Moreover, since the cut-off of the observed luminosity has not been yet determined only lower limits to the age of the halo population can be placed. We conclude that the current observed sample of the halo white dwarf population is still too small to obtain definite conclusions about the properties of the stellar halo, and the recently computed white dwarf cooling sequences which incorporate residual hydrogen burning should be assessed using metal-poor globular clusters.Comment: 9 pages, 9 figures, accepted for publication in A&

Los suelos en la enseñanza de la teoría ácido-base de Lewis : una estrategia didáctica de aprendizaje por investigación

This article describes and analyses the results obtained in a didactical experimental strategy, structured in the Teaching and Learning model which is based on research. The students are involved in situations, where problems related with the soil are used in order to help the significative construction of the acid and base's concepts related to the Lewis' Theory in order to increase the students mental ability for analysing and synthesizing and also to develop their attitudes towards science

A white dwarf cooling age of 8 Gyr for NGC 6791 from physical separation processes

NGC 6791 is a well studied open cluster1 that it is so close to us that can be imaged down to very faint luminosities. The main sequence turn-off age (~8 Gyr) and the age derived from the termination of the white dwarf cooling sequence (~6 Gyr) are significantly different. One possible explanation is that as white dwarfs cool, one of the ashes of helium burning, 22Ne, sinks in the deep interior of these stars. At lower temperatures, white dwarfs are expected to crystallise and phase separation of the main constituents of the core of a typical white dwarf, 12C and 16O, is expected to occur. This sequence of events is expected to introduce significant delays in the cooling times, but has not hitherto been proven. Here we report that, as theoretically anticipated, physical separation processes occur in the cores of white dwarfs, solving the age discrepancy for NGC 6791.Comment: 3 pages, 2 figures, published in Natur

New objects in old structures: The Iron Age hoard of the Palacio III megalithic funerary complex (Almadén de la Plata, Seville, Spain)

Cultural contact, exchange and interaction feature high in the list of challenging topics of current research on European Prehistory. Not far off is the issue of the changing role of monuments in the making and maintaining of key cultural devices such as memory and identity. Addressing both these highly-debated issues from a science-based perspective, in this paper we look at an unusual case study set in southern Iberia and illustrate how these archaeological questions can benefit from robust materials-science approaches.We present the contextual, morphological and analytical study of an exceptional Early Iron Age hoard composed of a number of different (and mostly exotic) materials such as amber, quartz, silver and ceramic. This hoard, found under the fallen orthostat of a megalithic structure built at least 2000 years earlier, throws new light on long-distance exchange networks and the effect they could have had on the cultural identities and social relations of local Iberian Early Iron Age communities. Moreover, the archaeometric study reveals how diverse and distant the sources of these item are (Northern Europe to Eastern and Western Mediterranean raw materials, as well as local and eastern technologies), therefore raising questions concerning the social mechanisms used to establish change and resistance in contexts of colonial encounter

Composición de ácidos grasos de la carne de capones de raza Mos y estirpes comerciales sacrificados a diferentes edades

Se ha estudiado la influencia de la raza [Mos (raza española autóctona), Sasso T-44 y X-44 (estirpes comerciales)] y la edad (5, 6, 7 y 8 meses) de los capones (gallos castrados) en la composición de ácidos grasos de la carne de la pechuga y del muslo. La carne de los capones de raza Mos presentó menor concentración de ácidos grasos monoinsaturados y mayor de poliinsaturados que la carne de las otras razas. Además, dichos capones mostraron mayor contenido de los ácidos margárico (C17:0) y esteárico (C18:0) que las estirpes comerciales; sin embargo, no hubo diferencias significativas entre las distintas razas en el total de ácidos grasos saturados. La carne de los animales más jóvenes mostró menor concentración de ácidos grasos monoinsaturados y mayor de poliinsaturados que la de los animales de mayor edad. Sin embargo, la edad influyó menos que la razaThe influence of the breed [Mos (Spanish indigenous breed), Sasso T-44 and X-44 (commercial strains)] and the age (5, 6, 7 and 8 months) of capons (castrated male cockerels) on the fatty acid compositions of breast and drumstick meat were studied. The meat of the Mos capons showed lower contents of monounsaturated fatty acids and higher concentrations of polyunsaturated fatty acids than those of the other breeds. In addition, the Mos breed showed higher contents of margaric acid (C17:0) and stearic acid (C18:0) as compared to the commercial strains; however, no significant effects of breed were observed in the total contents of saturated fatty acids in the meat. The meat of the youngest animals showed lower contents of monounsaturated fatty acids and higher concentrations of polyunsaturated fatty acids than that of the older ones. Nevertheless, the effect of age was less important than the effect of breedThis study was financially supported by project PGIDIT04RAG012E [Consellería de Innovación, Industria e Comercio da Xunta de Galicia and Asociación de Criadores de Capón de Vilalba]S

Design of a rib impactor equipment

The human ribs must be analyzed as long and as curved bones, due to their physiology. For the development of an experimental equipment that simulate the application of loads, over the rib in the moment of a frontal collision in an automobile with seat belt, it was applied a methodology that constituted in the identification of needs and the variables which led the design of 3D model, from this it was used the technique of fused deposition modeling for the development of the equipment pieces. The supports that hold the rib ends were design with two and three degrees of freedom that allows the simulation of rib movement with the spine and the breastbone in the breathing. For the simulation of the seat belt, it was determined to applied two loads over the front part of the rib from the sagittal and lateral plane respectively, for this it was made a displacement through a lineal actuator with a speed of 4mm/s. The outcomes shown a design of an equipment able to obtain the load parameters required to generate fractures in rib specimens. The equipment may be used for the study of specimens with nearby geometries to the rib taken as a reference

Evolución de las actitudes de alumnos ante el aprendizaje del inglés mediante el uso de la pizarra digital interactiva

We begin to be aware of the huge change our education has experimented recently as a consequence of the use of some technological resources so common nowadays. This situation has created new teaching-learning processes and roles, causing new pupils’ attitudes toward those subjects that are taught. The present work focuses on the attitudinal changes that several pupils from a school of Badajoz experiment when the Interactive Digital Whiteboard is taken into the English classroom and used as part of an experimental process, developed in three sessions, with different activities such as vocabulary games or recipes. An attitude scale based on the Osgood’s Semantic Differential has been developed in order to adapt it to our sample (8 years old). The results we get from the pretest-postest show an improvement of those pupils’ attitudes toward English, so we can somehow relate the use of this technological tool and a higher interest for the subject studied.Desde hace unos años la educación está experimentando grandes cambios, en gran parte debido a la incorporación de recursos o herramientas tecnológicas presentes en nuestro mundo actual. Esto, sin duda, ha generado cambios en los procesos de enseñanzaaprendizaje, promoviendo, como consecuencia, nuevas actitudes de los alumnos ante las materias. Este trabajo aborda los cambios actitudinales de un grupo de alumnos de un centro educativo de la provincia de Badajoz al introducir la Pizarra Digital Interactiva en el proceso de enseñanza-aprendizaje de la lengua inglesa durante un periodo de tres sesiones, en las que se han desarrollado diferentes actividades. Para la evaluación de estos cambios se ha utilizado una escala de actitudes según el modelo de Diferencial Semántico de Osgood, Succi y Tannenbaum (1957), adaptada a la edad de los alumnos de la muestra, ocho años. Los datos obtenidos, mediante un contraste pretest-postest, muestran una mejoría de las actitudes de dichos alumnos hacia dicha materia, por lo que podemos vincular el uso de este recurso tecnológico con un mayor interés por ella

Myristic acid potentiates palmitic acid-induced lipotoxicity and steatohepatitis associated with lipodystrophy by sustaning de novo ceramide synthesis.

Palmitic acid (PA) induces hepatocyte apoptosis and fuels de novo ceramide synthesis in the endoplasmic reticulum (ER). Myristic acid (MA), a free fatty acid highly abundant in copra/palmist oils, is a predictor of nonalcoholic steatohepatitis (NASH) and stimulates ceramide synthesis. Here we investigated the synergism between MA and PA in ceramide synthesis, ER stress, lipotoxicity and NASH. Unlike PA, MA is not lipotoxic but potentiated PA-mediated lipoapoptosis, ER stress, caspase-3 activation and cytochrome c release in primary mouse hepatocytes (PMH). Moreover, MA kinetically sustained PA-induced total ceramide content by stimulating dehydroceramide desaturase and switched the ceramide profile from decreased to increased ceramide 14:0/ceramide16:0, without changing medium and long-chain ceramide species. PMH were more sensitive to equimolar ceramide14:0/ceramide16:0 exposure, which mimics the outcome of PA plus MA treatment on ceramide homeostasis, than to either ceramide alone. Treatment with myriocin to inhibit ceramide synthesis and tauroursodeoxycholic acid to prevent ER stress ameliorated PA plus MA induced apoptosis, similar to the protection afforded by the antioxidant BHA, the pan-caspase inhibitor z-VAD-Fmk and JNK inhibition. Moreover, ruthenium red protected PMH against PA and MA-induced cell death. Recapitulating in vitro findings, mice fed a diet enriched in PA plus MA exhibited lipodystrophy, hepatosplenomegaly, increased liver ceramide content and cholesterol levels, ER stress, liver damage, inflammation and fibrosis compared to mice fed diets enriched in PA or MA alone. The deleterious effects of PA plus MA-enriched diet were largely prevented by in vivo myriocin treatment. These findings indicate a causal link between ceramide synthesis and ER stress in lipotoxicity, and imply that the consumption of diets enriched in MA and PA can cause NASH associated with lipodystrophy