Compositional Time Series: An Application

The composition of the labour force is an important economic factor for a country. Often the changes in proportions of different groups are of interest. I this paper we study a monthly compositional time series from the Swedish Labour Force Survey from 1994 to 2005. Three models are studied: the ILR-transformed series, the ILR-transformation of the compositional differenced series of order 1, and the ILRtransformation of the compositional differenced series of order 12. For each of the three models a VAR-model is fitted based on the data 1994-2003. We predict the time series 15 steps ahead and calculate 95 % prediction regions. The predictions of the three models are compared with actual values using MAD and MSE and the prediction regions are compared graphically in a ternary time series plot. We conclude that the first, and simplest, model possesses the best predictive power of the three models

Statistical evidences of cyclic changes in volcanic gas chemistry composition by inverse modelling

The identification of compositional changes in fumarolic gases of active and quiescent volcanoes is one of the most important targets in monitoring programs. From a general point of view, many systematic (often cyclic) and random processes control the chemistry of gas discharges, making difficult to produce a convincing mathematical-statistical modelling. Changes in the chemical composition of volcanic gases sampled at Vulcano Island (Aeolian Arc, Sicily, Italy) from eight different fumaroles located in the northern sector of the summit crater (La Fossa) have been analysed by considering their dependence from time in the period 2000-2007. Each intermediate chemical composition has been considered as potentially derived from the contribution of the two temporal extremes represented by the 2000 and 2007 samples, respectively, by using inverse modelling methodologies for compositional data. Data pertaining to fumaroles F5 and F27, located on the rim and in the inner part of La Fossa crater, respectively, have been used to achieve the proposed aim. The statistical approach has allowed us to highlight the presence of random and not random fluctuations, features useful to understand how the volcanic system works, opening new perspectives in sampling strategies and in the evaluation of the natural risk related to a quiescent volcano

Modelling of Mercury’s surface composition and remote detection from the orbit with the BepiColombo Mercury Planetary Orbiter

It can be assumed that the composition of Mercury’s thin gas envelope (exosphere) is related to the composition of the planets crustal materials. If this relationship is true, then inferences regarding the bulk chemistry of the planet might be made from a thorough exospheric study. The most vexing of all unsolved problems is the uncertainty in the source of each component. Historically, it has been believed that H and He come primarily from the solar wind, while Na and K originate from volatilized materials partitioned between Mercury’s crust and meteoritic impactors. The processes that eject atoms and molecules into the exosphere of Mercury are generally considered to be thermal vaporization, photonstimulated desorption (PSD), impact vaporization, and ion sputtering. Each of these processes has its own temporal and spatial dependence. The exosphere is strongly influenced by Mercury’s highly elliptical orbit and rapid orbital speed. As a consequence the surface undergoes large fluctuations in temperature and experiences differences of insolation with longitude. We will discuss these processes but focus more on the expected surface composition and solar wind particle sputtering which releases material like Ca and other elements from the surface minerals and discuss the relevance of composition modelling

L'??s del catal?? a la doc??ncia i la recerca a la Universitat de les Illes Balears : cursos 1999-2000 a 2005-2006. 'El uso del catal??n en la docencia y la investigaci??n en la Universidad de las Islas Baleares : cursos 1999-2000 a 2005-2006'

Resumen tomado de la publicaci??n

La llengua catalana a la UIB : l'??s a la doc??ncia i la recerca a la Universitat de les Illes Balears (cursos 1999-2000 a 2007-2008) i coneixement subjectiu (autoavaluaci??) de l'alumnat (curs 2008-2009). Una actualitzaci??. 'La lengua catalana en la UIB : el uso en la docencia y la investigaci??n en la Universidad de las Islas Baleares (cursos 1999-2000 a 2007-2008) y conocimiento subjetivo (autoevaluaci??n) del alumnado (curso 2008-2009). Una actualizaci??n'

Resumen tomado del autor

Data Manipulation.doc (9)

Notes on use of SPSS. Used in Research Skills for Biomedical Science

Charts.doc (7)

Notes on use of SPSS. Used in Research Skills for Biomedical Science

Defining Data.doc (5)

Notes on use of SPSS. Used in Research Skills for Biomedical Science

Selecting Cases.doc (A2)

Notes on use of SPSS. Used in Research Skills for Biomedical Science

Modifying Charts_notes.doc (8)

Notes on use of SPSS. Used in Research Skills for Biomedical Science

Research Skills for 2009.doc

Used in Research Skills for Biomedical Science. This links to a set of Word and Powerpoint documents

SPSS Basics.doc (4)

Notes on use of SPSS. Used in Research Skills for Biomedical Science

Reading Other File Formats.doc (A1)

Notes on how to get from Excel, Access and Textfiles into SPSS. Used in Research Skills for Biomedical Science

Recoding Data and Syntax Files.doc (6)

Notes on how to recode data and use of Synyax files in SPSS. Used in Research Skills for Biomedical Science

Modifying Charts_Practical.doc (8)

Practical exercises for modifying SPSS charts. Used in Research Skills for Biomedical Science