Studies in stoichiometry with compositional data

Geochemical data that is derived from the whole or partial analysis of various geologic materials represent a composition of mineralogies or solute species. Minerals are composed of structured relationships between cations and anions which, through atomic and molecular forces, keep the elements bound in specific configurations. The chemical compositions of minerals have specific relationships that are governed by these molecular controls. In the case of olivine, there is a well-defined relationship between Mn-Fe-Mg with Si. Balances between the principal elements defining olivine composition and other significant constituents in the composition (Al, Ti) have been defined, resulting in a near-linear relationship between the logarithmic relative proportion of Si versus (MgMnFe) and Mg versus (MnFe), which is typically described but poorly illustrated in the simplex. The present contribution corresponds to ongoing research, which attempts to relate stoichiometry and geochemical data using compositional geometry. We describe here the approach by which stoichiometric relationships based on mineralogical constraints can be accounted for in the space of simplicial coordinates using olivines as an example. Further examples for other mineral types (plagioclases and more complex minerals such as clays) are needed. Issues that remain to be dealt with include the reduction of a bulk chemical composition of a rock comprised of several minerals from which appropriate balances can be used to describe the composition in a realistic mineralogical framework. The overall objective of our research is to answer the question: In the cases where the mineralogy is unknown, are there suitable proxies that can be substituted? Kew words: Aitchison geometry, balances, mineral composition, oxides

Application of compositional data analysis to geochemical data of marine sediments

In an earlier investigation (Burger et al., 2000) five sediment cores near the Rodrigues Triple Junction in the Indian Ocean were studied applying classical statistical methods (fuzzy c-means clustering, linear mixing model, principal component analysis) for the extraction of endmembers and evaluating the spatial and temporal variation of geochemical signals. Three main factors of sedimentation were expected by the marine geologists: a volcano-genetic, a hydro-hydrothermal and an ultra-basic factor. The display of fuzzy membership values and/or factor scores versus depth provided consistent results for two factors only; the ultra-basic component could not be identified. The reason for this may be that only traditional statistical methods were applied, i.e. the untransformed components were used and the cosine-theta coefficient as similarity measure. During the last decade considerable progress in compositional data analysis was made and many case studies were published using new tools for exploratory analysis of these data. Therefore it makes sense to check if the application of suitable data transformations, reduction of the D-part simplex to two or three factors and visual interpretation of the factor scores would lead to a revision of earlier results and to answers to open questions . In this paper we follow the lines of a paper of R. Tolosana- Delgado et al. (2005) starting with a problem-oriented interpretation of the biplot scattergram, extracting compositional factors, ilr-transformation of the components and visualization of the factor scores in a spatial context: The compositional factors will be plotted versus depth (time) of the core samples in order to facilitate the identification of the expected sources of the sedimentary process. Kew words: compositional data analysis, biplot, deep sea sediments

Compositions in life science data

The aim of this talk is to convince the reader that there are a lot of interesting statistical problems in presentday life science data analysis which seem ultimately connected with compositional statistics. Key words: SAGE, cDNA microarrays, (1D-)NMR, virus quasispecies

Elemental analysis of New Zealand Nephrite Jade (pounamu) for forensic purposes

Pounamu (NZ jade), or nephrite, is a protected mineral in its natural form following the transfer of ownership back to Ngai Tahu under the Ngai Tahu (Pounamu Vesting) Act 1997. Any theft of nephrite is prosecutable under the Crimes Act 1961. Scientific evidence is essential in cases where origin is disputed. A robust method for discrimination of this material through the use of elemental analysis and compositional data analysis is required. Initial studies have characterised the variability within a given nephrite source. This has included investigation of both in situ outcrops and alluvial material. Methods for the discrimination of two geographically close nephrite sources are being developed. Key Words: forensic, jade, nephrite, laser ablation, inductively coupled plasma mass spectrometry, multivariate analysis, elemental analysis, compositional data analysis

Analysis of Pleistocene paleodrainage evolution in the Po Basin (Italy) by multivariate statistical techniques

In order to obtain a high-resolution Pleistocene stratigraphy, eleven continuously cored boreholes, 100 to 220m deep were drilled in the northern part of the Po Plain by Regione Lombardia in the last five years. Quantitative provenance analysis (QPA, Weltje and von Eynatten, 2004) of Pleistocene sands was carried out by using multivariate statistical analysis (principal component analysis, PCA, and similarity analysis) on an integrated data set, including high-resolution bulk petrography and heavy-mineral analyses on Pleistocene sands and of 250 major and minor modern rivers draining the southern flank of the Alps from West to East (Garzanti et al, 2004; 2006). Prior to the onset of major Alpine glaciations, metamorphic and quartzofeldspathic detritus from the Western and Central Alps was carried from the axial belt to the Po basin longitudinally parallel to the SouthAlpine belt by a trunk river (Vezzoli and Garzanti, 2008). This scenario rapidly changed during the marine isotope stage 22 (0.87 Ma), with the onset of the first major Pleistocene glaciation in the Alps (Muttoni et al, 2003). PCA and similarity analysis from core samples show that the longitudinal trunk river at this time was shifted southward by the rapid southward and westward progradation of transverse alluvial river systems fed from the Central and Southern Alps. Sediments were transported southward by braided river systems as well as glacial sediments transported by Alpine valley glaciers invaded the alluvial plain. Kew words: Detrital modes; Modern sands; Provenance; Principal Components Analysis; Similarity, Canberra Distance; palaeodrainage

CODAMAT: a modern analogue techinque for compositional data

The quantitative estimation of Sea Surface Temperatures from fossils assemblages is a fundamental issue in palaeoclimatic and paleooceanographic investigations. The Modern Analogue Technique, a widely adopted method based on direct comparison of fossil assemblages with modern coretop samples, was revised with the aim of conforming it to compositional data analysis. The new CODAMAT method was developed by adopting the Aitchison metric as distance measure. Modern coretop datasets are characterised by a large amount of zeros. The zero replacement was carried out by adopting a Bayesian approach to the zero replacement, based on a posterior estimation of the parameter of the multinomial distribution. The number of modern analogues from which reconstructing the SST was determined by means of a multiple approach by considering the Proxies correlation matrix, Standardized Residual Sum of Squares and Mean Squared Distance. This new CODAMAT method was applied to the planktonic foraminiferal assemblages of a core recovered in the Tyrrhenian Sea. Kew words: Modern analogues, Aitchison distance, Proxies correlation matrix, Standardized Residual Sum of Squares

Aprenentatge per problemes

Presentació de l’experiència que s’ha portat a terme en l’Escola Politècnica Superior de la UdG en l’assignatura de Fonaments Físics per l’Enginyeria aplicant com a tècnica l’aprenentatge basat en problemes: Project Based Learning (APB)

Organització de la producció: pràctiques [versió comprimida]

Aquest manual recull un conjunt de pràctiques que mitjançant la utilització de programaris específics complementen l’aprenentatge en l’àmbit de l’Organització de la Producció. El llibre es divideix en dues parts ben diferenciades: una primera per a treballar amb programaris destinats a la simulació dels processos productius, i una segona per a aprendre a gestionar diàriament la producció. La primera part està dissenyada per a utilitzar el programari Taylor II, i la segona l’ERP Microsoft Business Solutions-Navision

La pesca

El estudio de este tema se centra en la valoraci??n del mar como fuente de recursos alimenticios y econ??micos acercando al alumno a los distintos aspectos del trabajo del hombre en los tres sectores de producci??n, ligados a la pesca. Se propone el m??todo de 'seguir la pista' que consiste en investigar los distintos pasos de un producto, en este caso el pescado, desde su origen hasta que llega a manos del consumidor. El trabajo en el aula y las salidas escolares a los distintos centros de producci??n, lonja, f??brica de conservas y centros comerciales, aportan elementos para trabajar aspectos relativos a la producci??n, industrial, su distribuci??n y su situaci??n en el mercado. Otros aspectos a trabajar son los orientados a desarrollar h??bitos y actitudes consumeristas. Se proponen una serie de fichas y experiencias para trabajar el tema: el trabajo del pescador, tipos de pesca y artes de pesca, localizaci??n de caladeros, etiquetado de productos aliment??cios, an??lisis de etiquetas de conserva. Este material se edita dentro de 'HABITAR', programa did??ctico para el estudio del medio, que ofert?? el Ayuntamiento de Gij??n a la comunidad educativa. El documento en s??, viene precedido por la presentaci??n de los principios educativos y otros de procedimiento que gu??an el programa.

Gu??a de recursos y materiales contra el racismo y la xenofobia : material did??ctico

En la la edici??n colabora el Ayuntamiento de Corvera de Asturias, el MEC, el CEPyR de Avil??s y el Vicerrectorado de Estudiantes de la Universidad de Oviedo

30 de enero : d??a escolar de la no-violencia y de la paz

En la edici??n colabora el Ministerio de Asuntos Sociales, la Direcci??n Provincial del MEC y el Centro de Profesores y Recursos de Avil??s (Asturias)

Programa de introducci??n a la Educaci??n Ambiental para profesores e inspectores de Ciencias Sociales de Ense??anza Media

Este m??dulo pretende ayudar a los profesores de Historia, Geograf??a, Estudios Sociales, Econom??a, Educaci??n C??vica, Hitoria del Arte y ??tica a impartir su materia, dot??ndola de un contenido medioambiental m??s amplio y profundo, se interrelacionan los problemas del medio ambiente con los principios f??sicos y biol??gicos necesarios para su comprensi??n. Se analizan los m??todos que los ense??antes podr??n utilizar para inculcar los conceptos ambientales a los alumnos en clase, a fin de aumentar su concienciaci??n al respecto. Al presentar los conceptos ambientales al mismo tiempo que los temas relativos a las Ciencias Sociales, sugieriendo m??todos, actividades, experiencias y t??cnicas de evaluaci??n, se pretende que el m??dulo resulte f??cil de utilizar para los profesores suscitando al mismo tiempo el inter??s del alumno por las cuestiones medioambientales. Entre otras se sugieren experiencias y actividades como: cuestionarios, realizaci??n de proyectos ficticios (an??lisis de la situaci??n, gui??n de la investigaci??n, evaluaci??n), juegos de simulaci??n, etc..

Cicle de Carnot (applet)

Simulació del cicle de Carnot

Cicle de Stirling (applet)

Simulació del cicle de Stirling

Cicle de Stirling real (applet)

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