Testing for Additive Outliers in Seasonally Integrated Time Series

The detection of additive outliers in integrated variables has attracted some attention recently, see e.g. Shin et al. (1996), Vogelsang (1999) and Perron and Rodriguez (2003). This paper serves several purposes. We prove the inconsistency of the test proposed by Vogelsang, we extend the tests proposed by Shin et al. and Perron and Rodriguez to the seasonal case, and we consider alternative ways of computing their tests. We also study the effects of periodically varying variances on the previous tests and demonstrate that these can be seriously size distorted. Subsequently, some new tests that allow for periodic heteroskedasticity are proposed.Additive outliers, outlier detection, integrated processes, periodic heteroscedasticity, seasonality.

Potentiostatic infrared titration of 11-Mercaptoundecanoic acid monolayers

Acknowledgment This work was supported by the Spanish DGICYT under grant CTQ2008-00371 and by the Junta de Andalucía under grant P07-FQM-02492.Peer reviewedPostprin

Using different null hypotheses to test for seasonal unit roots in economic time series

Este trabajo discute la aplicación de diferentes técnicas para determinar las propiedades estacionales de datos trimestrales. En particular, enfocamos el test de Hylleberg et al. y los estadísticos propuestos por Canova y Hansen y los aplicamos a una serie microeconómica. El primer método detecta una raíz unitaria en la frecuencia cero pero ninguna raíz unitaria estacional. El segundo revela que la serie tiene un patrón estacional estadísticamente significativo con algunos coeficientes de las dummies estacionales que no son constantes. En el caso de un resultado obtenido con ambos métodos y que representa una contradicción, ofrecemos una posible interpretación para el mismo.This paper tries to make a contribution by discussing the application of different testing procedures to determine the seasonal properties of quarterly data. We focus on the Hylleberg et al. and on the Canova-Hansen tests. The former detect a unit root at the zero frequency but no seasonal unit roots. The latter reveal that the series displays a statistically significant seasonal pattern with changing coefficients of some seasonal dummy variables. The CH tests finding of a seasonal unit root at frequency π does not agree with the HEGY-type test results. An explanation is given to try to interpret these two contradictory outcomes.Instituto de Investigaciones Económica

Using different null hypotheses to test for seasonal unit roots in economic time series

Este trabajo discute la aplicación de diferentes técnicas para determinar las propiedades estacionales de datos trimestrales. En particular, enfocamos el test de Hylleberg et al. y los estadísticos propuestos por Canova y Hansen y los aplicamos a una serie microeconómica. El primer método detecta una raíz unitaria en la frecuencia cero pero ninguna raíz unitaria estacional. El segundo revela que la serie tiene un patrón estacional estadísticamente significativo con algunos coeficientes de las dummies estacionales que no son constantes. En el caso de un resultado obtenido con ambos métodos y que representa una contradicción, ofrecemos una posible interpretación para el mismo.This paper tries to make a contribution by discussing the application of different testing procedures to determine the seasonal properties of quarterly data. We focus on the Hylleberg et al. and on the Canova-Hansen tests. The former detect a unit root at the zero frequency but no seasonal unit roots. The latter reveal that the series displays a statistically significant seasonal pattern with changing coefficients of some seasonal dummy variables. The CH tests finding of a seasonal unit root at frequency π does not agree with the HEGY-type test results. An explanation is given to try to interpret these two contradictory outcomes.Instituto de Investigaciones Económica

Mean curvature and compactification of surfaces in a negatively curved Cartan–Hadamard manifold

We state and prove a Chern–Osserman-type inequality in terms of the volume growth for complete surfaces with controlled mean curvature properly immersed in a Cartan–Hadamard manifold N with sectional curvatures bounded from above by a negative quantity KN ≤ b < 0

Arxiu docent d'imatges radiològiques digitalitzadas (www.radiologico.org)

El "Arxiu Docent d'imatges radiològiques" és un projecte que sorgeix després de l'experiència de més de 25 anys d'ensenyament als alumnes de tercer i sisè de medicina. Es basa en una col·lecció de casos que es presenten en pantalla, amb la finalitat d'oferir a l'alumne un primer contacte amb imatges radiològiques digitalitzades i proporcionar un entrenament visual, ja sigui per a distingir les diferents tècniques radiològiques, com per a aprendre a identificar les troballes radiològiques més habituals. Està organitzat per òrgan-sistema i presenta dues parts iguals cadascun d'ells: una part corresponent a tècniques radiològiques i anatomia normal i altra part per a la semiologia i patologia radiològica. Cada figura o imatge radiològica té un peu explicatiu curt. No es pretén donar una explicació completa i exhaustiva. Es tracta d'un Arxiu actiu on els professors poden anar col·locant i actualitzant tècniques radiològiques i imatges d'interès. Amb aquesta finalitat, hi ha dos apartats en el index general de cada òrgan-sistema, dedicats a casos d'interès en les pràctiques radiològiques i a casos problema per a discussió en classe

Territorial inequalities, ecological and material footprints of the energy transition: case study of the Cantabrian-Mediterranean Bioregion

This study develops a methodology to assess the energy transition’s territorial, ecological and material impacts on regions. As a case study, the methodology is applied to the Cantabrian-Mediterranean Bioregion, a geographical area constituting eight autonomous communities located in the north of Spain. Two energy demand scenarios for 2030 and 2050 were assessed. The 2030 scenario is based on the Spanish government’s planning, and the 2050 scenario constitutes a net-zero emission economy based on electrification. Energy dependence between autonomous communities, energy and raw material needs, and availability are obtained for both scenarios. Results show a high imbalance between energy producer–consumer autonomous communities and an ecological and critical material deficit for the Bioregion. Two alternative scenarios are proposed, one based on self-sufficiency to ensure a balanced energy transition and another based on energy and material efficiency seeking that the ecological and critical material footprints do not surpass the planet’s carrying capacity. The indicators and methodology proposed can be easily replicated elsewhere and help develop more equitable and sustainable territorial planning strategies