La Climatología en los diferentes niveles de la enseñanza en España

El estudio pretende mostrar el interés de la ciencia, y, por consiguiente, la necesidad de prestarle una mayor atención ya desde los primeros niveles de la enseñanza

LA INMUNIZACIÓN FINANCIERA: EVALUACIÓN DE DIFERENTES ESTRUCTURAS DE CARTERA

Although traditional immunization offers protection against parallel movements of theterm structure of interest rates (TSIR) exclusively, numerous studies have shown that thisstrategy offers near perfect immunization at an empirical level. This work reveals some of thefactors that justify this success by analyzing the influence of portfolio structure on the goal ofimmunization.Focusing on the Spanish government debt market in the period 1992-1999, we find thatthe portfolio structure is not trivial for immunization. When portfolios include a bond maturingnear the end of the holding period, the exposition to non parallel shifts of the TSIR dropsnotably, and the difficulties to set up the duration-matching portfolios lessen. These two forceslead to a more effective immunization. Also, the maturity bond it is shown to be necessary inthe portfolios with minimum M-Absolute (Nawalkha and Chambers, 1996) to obtain a returnclose enough to the target return. Nevertheless, the strategies based on M-Squared (Fong andVasicek, 1984) and M-Absolute are overcome by other duration-matching strategies that imposepeculiar portfolio structures. Aunque la estrategia de inmunización tradicional defiende a una cartera de renta fija exclusivamente de los desplazamientos paralelos de la curva de tipos, a nivel empírico numerosas investigaciones han puesto de manifiesto que esta estrategia ofrece un excelente grado de inmunización. En este trabajo desvelamos algunos de los factores que justifican el éxito de la estrategia de inmunización tradicional centrándonos, en particular, en la influencia que tiene la estructura de la cartera inmunizada. Empleando como marco de análisis el mercado español de deuda pública en el periodo 1992-1999, nuestros resultados evidencian que la estructura de cartera no es una cuestión trivial para el buen funcionamiento de la estrategia de inmunización tradicional. Incluir un bono con vencimiento cercano al fin del horizonte de planificación provoca reducciones significativas del grado de exposición al riesgo de las carteras y minora las dificultades que pueden plantearse a la hora de construir las carteras inmunizadas, todo lo cual da lugar a un mayor grado de inmunización. La posibilidad de contar con este bono es necesaria para que la estrategia basada en la M-Absoluta (Nawalkha y Chambers, 1996) garantice un grado de inmunización suficiente. No obstante, las estrategias basadas en M-Cuadrado (Fong y Vasicek, 1984) y M-Absoluta son superadas por otras estrategias basadas en la duración tradicional que imponen determinadas configuraciones de cartera.inmunización, duración, tipos de interés, gestión de riesgos, renta fija immunization, duration, interest rate, risk management, fixed income

UN ESTUDIO EMPÍRICO DE TRANSMISIÓN MONETARIA EN EUROPA

The aim of this paper is to determine whether there have been differences in the effectiveness of the transmission mechanism of monetary policy in Germany, France, Italy, Spain and the United Kingdom since Economic and Monetary Union (EMU) establishment. The analysis is based on the fulfilment of the Expectations Hypothesis under rational expectations and the methodology is implemented through a VAR model with ARCH disturbances.The evidence obtained shows that the analysed countries started from different monetary transmission structures and that these differences still remain at a larger extent. Also, the EMU seems not to have increased the power of the transmission mechanism in every single country. Its contribution is shown to be poor in the case of the Mediterranean countries (Spain and Italy). However, in Continental countries, Germany and especially in France, the effectiveness of monetary transmission is outstanding nowadays. Este trabajo analiza las diferencias en la efectividad del mecanismo de transmisión monetaria en Alemania, Francia, Italia, España y el Reino Unido en el periodo previo y posterior a la UEM. El análisis se centra en el estudio de la estructura temporal de los tipos de interés y emplea como marco analítico el contraste de la Teoría de las Expectativas bajo la hipótesis de racionalidad. La metodología econométrica se implementa mediante un modelo VAR con perturbaciones ARCH.Los resultados obtenidos muestran que los países analizados partían de estructuras de transmisión monetaria diferentes que aún permanecen en la actualidad. La UEM no parece haber aumentado significativamente la capacidad de transmisión monetaria en cada uno de ellos. En los países mediterráneos (España e Italia) los resultados muestran una transmisión débil, mientras que en los países continentales (Alemania y Francia) la evidencia es mucho mayor y hasta un horizonte de medio plazo.Estructura temporal, transmisión monetaria , VAR, cointegración, expectativas Term structure, monetary transmission, VAR, cointegration, expectations hypothesis

La importancia del conocimiento de las fluctuaciones climáticas en los estudios históricos. Aproximación al clima de Tarragona durante el siglo XVIII

A pesar de los importantes progresos de las ciencias y las técnicas, el hombre ha sido siempre vulnerable a las condiciones atmosféricas. Si el hombre prehistórico se encontró bajo la dependencia del clima, aún sin pretender adoptar una posición determinista, se puede decir que también el hombre del siglo XVIII como el del XX han sufrido la ley del tiempo atmosférico

Microplastic and an associated metal contaminant (Palladium) impair the immune response against pathogenic bacteria of the marine bivalve Mytilus galloprovincialis

Microplastics (MPs) are widely distributed in marine environments and have been reported to cause harmful physiological effects in marine bivalves including immune modulation. While Mytilus galloprovincialis is a model species in environmental monitoring studies, little is known regarding the effects of MPs and palladium (Pd), an emerging contaminant, metal on the immune functioning of this species. In this study, gills and gland samples of specimens of M.ytilus galloprovincialis which were exposed to the same particle concentration (2.5 x 10 66 μm3μm /mL) of Control (microalgae), MP (virgin microplastics) and MP-Pd (Pd spiked microplastics) once an hour during 4 hours. Thus, mussels were exposed to 6095 ng of Pd/mussel. Samples analyzed were collected after 4 and 24 hours of exposure and after 24, 48 and 144 hours of depuration. Several innate immune activities (lysozymes, peroxidase, protease, antiprotease, and bactericidal activities) were analyzed. Our data demonstrated that after 24 hours of exposure to MP, a decrease in lysozymes and peroxidase activities occurred, but not in the bactericidal activity which increased. However, when MP-Pd was used, an increase in all these activities was observed compared to MP levels group. These data suggest that when MP are spiked with Pd, the latter compound might induce an inflammatory process that will results in higher levels of most of all the immune activities analyzed. In the gland, however, most of the activity levels were decreased upon MP-Pd treatment compared to MP levels at different time point of exposure depending on the activity. Interestingly, after 24 hours of removing the pollutants from the water, most of the activity levels in both tissues, gills and gland, were recovered to control levels, but not the bactericidal activity. Considering this impairment of the bactericidal activity against possible pathogenic bacteria, a potential threat to mussels population in a polluted scenario is highly plausible

Seasonal variability of antioxidant biomarkers in mussels Mytilus galloprovincialis from the Spanish N-NW coast.

Marine organisms are highly seasonal animals in relation to their physiology which depends, among other factors, on their annual cycle of reproduction. In bivalves, reproductive cycle is regulated by two main environmental factors: temperature and food availability. Specifically, bivalves are undergoing high variable environmental conditions. Integrated pollution monitoring carried out by the IEO along the N-NW coast of Spain has evidenced that the variability of the environmental conditions produce spatial differences in mussel condition which seems to mask the biomarker responses to pollution. Thus, there is a need to study the natural variability of biological responses used as pollution biomarkers at different seasons and in different habitats in order to establish an adequate link between chemical pollution and biological responses. This study aims to assess the natural variability of some biomarker responses on the mussel Mytilus galloprovincialis in 5 different sites from the Spanish Marine Pollution Monitoring Program which are differentiated in their natural ecology and their anthropogenic pressure. The potential influence of environmental and endogenous factors that can cause biomarker´s seasonal fluctuations was examined. Biomarkers analyzed in this study are considered among the most usefull biological tools applied in pollution monitoring programs, including exposure indicators (superoxide dismutase –SOD-, catalase –CAT-, glutathione reductase –GR-, glutathione peroxidase –GPx-, glutathione-s-transfersase –GST-) and a damage indicator (lipid peroxidation –LPO-). Mussel biological characterization from a histological and anatomical point of view was also performed. Results evidenced that biomarkers were clearly influenced by the annual cycle (all of them were affected by the season) but also significant differences between sites were found in some biomarkers (GR and GST). Thus, not only environmental but also endogenous factors must be considered in monitoring programs in the study of biomarkers responses.Society of Environmenta Toxicology and Chemistry (SETAC

Impact of size and food concentration on clearance and ingestion rates in the clam Ruditapes decussates (Linnaeus, 1758)

The impact of food concentration (C) and water flow on the clearance (TA) and ingestion (TI) rates of the clam Ruditapes decussates (Linnaeus, 1758) was studied, using different-sized specimens. We found no relationship between C and TA, whereas there was a significant relationship between C and TI (TI = 24.757 + 0.576 C). The relationship between TA and the clams' live weight (PV) was also significant (TA = 4.292 PV0.683). A close relationship between PV and TI was found only when food availability (AD), a parameter that includes food concentration and flow, was constant. When it was not, the equation TI = 64.089 + 0.015 PV + 0.546 AD appears to explain 96.1% of TI variability.Se estudia el efecto de la concentración de alimento (C) y el flujo sobre las tasas de aclaramiento (TA) e ingestión (TI) de Ruditapes decussatus (Linnaeus, 1758) con ejemplares de diferentes tamaños. En esta especie no se observa relación entre C y TA, mientras que entre TI y C la relación es significativa: TI = 24,757 + 0,576 C. Igualmente es significativa la relación entre TA y el peso vivo (PV): TA = 4,292 PV0,683. PV y TI guardan una estrecha relación sólo en caso de que el alimento disponible (AD), variable que engloba la concentración de alimento y el flujo, se mantenga constante. En caso contrario, se propone la utilización de la ecuación TI = 64,089 + 0,015 PV + 0,546 AD que explica el 96,1 % de la variabilidad de TI.Instituto Español de OceanografíaVersión de editor

Energy balance of the clam Ruditapes decussatus (Linnaeus, 1758)

The effect of food ingestion and clam size on absorption efficiency, absorption rate and oxygen consumption of the clam Ruditapes decussatus (L., 1758) was studied. Absorption efficiency (AE) was related to the ingestion rate (IR) following the non-lineal equation AE = 0.836 + e-0.64/IR (P 0.01; n = 26; r² = 0.321) No significant relationship as found between AE and clam live weight, whereas there was a relationship between absorption rate (AR) and IR, following the expression AR = 0.8248 IR - 0.0344 (P 0.001; n = 26; r² = 0.964) The maintenance food ration for a 2 g (live weight) clam was estimated as 1.528 J/h, equivalent to a daily food ration of 0.08 mg organic matter/g clam live weight.Se estudia el efecto de la ingestión de alimento y el tamaño de las almejas sobre la eficiencia de absorción, la tasa de absorción y el consumo de oxígeno de Ruditapes decussatus (L., 1758). La eficiencia de absorción (EA) se relaciona con la tasa de ingestión (TI) siguiendo el modelo no lineal EA = 0,836 + e-0,64/TI (P 0,01; n = 26; r² = 0,321) Entre EA y el peso vivo de las almejas no existe una relación significativa, mientras que sí la hay entre la tasa de absorción (TA) y TI, y responde a la ecuación TA = 0,8248 TI - 0,0344 (P 0,001; n = 26; r² = 0,964) La ración de mantenimiento de una almeja de 2 g de peso vivo es de 1,528 J/h, que se corresponde con una dieta diaria de 0,08 mg de materia orgánica por gramo de peso vivo.Instituto Español de Oceanografí