Mapping texture domains in quartzite microstructures

The paper is concerned with the combined application of two methods for microstructure and texture analysis: (1) optical orientation and misorientation imaging and (2) autocorrelation function (ACF). Using two different samples, the usefulness of the methods and the quality of the results are discussed. One sample is a quartzite layer from the limb of a small scale fold in the Suretta Nappe (ValAvers, Switzerland) which was deformed under upper greenschist conditions, the other is a sample of Black Hills quartzite, experimentally sheared in dislocation creep. Using the method of computer-integrated polarization microscopy (CIP), c-axis orientation and misorientation images were prepared and pole figures were calculated from the azimuth and inclination images. Misorientation images were prepared and analyzed in a number of ways: (1) In as much as misorientation images constitute texture maps, they visualize the geometry and spatial distribution of texture domains; they show if the texture domains are spatially coherent, i.e., if the rock is domainal or not. (2) Thresholded misorientation images allow the calculation of the volume fraction of texture domains, which is a means of estimating the texture intensification independent of the shape of the pole figure skeleton. (3) From the ACF of thresholded misorientation images the average grain size and shape in those domains can be derived. (4) From the shape of the domains (if they exist as spatial entities), the strain or strain partitioning as well as the rheological contrast can be estimated. The paper seeks to demonstrate the importance of localized texture analysis. The aim is to discuss the quality of the results that can be obtained. The samples were chosen because one is domainal the other one is not. A full discussion of the geological implications of the results of the analysis is outside the scope of this contributio

The wooden «Chasuble Madonnas» from Ger, IX, Targasona and Talló : about the iconography of Catalan Madonna statues in the Romanesque period

Numerous wooden Madonna statues of the Romanesque style have survived from medieval Catalonia, which show the Virgin as sedes sapientiae. The thematized exemplars from Ger (second half 12th century), IX (last third 12th century), Targasona (early 13th century) attract the attention of today's viewer by an iconographic peculiarity. Explicitly, they show the enthroned Mother of God, as it will be pointed out, in the priestly chasuble. The chasuble most probably represents Mary's significance as symbol of the hierarchical or institutionalized church and also alludes to the conception of Mary being interpreted as priest or ministerial priest, which became more and more popular in the 12th century. The throne representations of the statues from Ger and Ix, which refer undoubtedly to the famous episcopal throne from the Girona Cathedral by its formal structure, will be related to this significant meaning, too. The iconographic type of the Catalan «Chasuble Madonna» is not to be found in the art of wood carving first, but in Romanesque mural paintings in the Pyrenean Valleys of North-West Cataloia. The historical and cultural sphere, which could have been responsible for the development and dissemination of this Madonna type respectively, will be discussed in the present article in the context of the 11th and 12th century church reform in Catalonia.A Catalunya han sobreviscut nombroses escultures d'estil romànic de la Verge, que la representen com a sedes sapientiae. Els exemplars de Ger (segona meitat del segle XII), IX (últim terç del segle XII) , Targasona (inicis del segle XIII) i Talió (inicis del segle XIII) criden l'atenció per una peculiaritat iconogràfica. Explícitament, figuren la Mare de Déu entronitzada i, com serà més detallat, vstida amb casulla. És molt probable que la casulla representi Maria com a símbol de l'església jerarquitzada o institucionalitzada i també al·ludeix al concepte de Maria com a sacerdot o ministeri sacerdotal, una idea que es va estenent al segle xii. Els trons de les talles de Ger i IX, que per la seva estructura formal es refereixen sens dubte al famós tron episcopal de la catedral de Girona, també es poden vincular al mateix significat. El tipus iconogràfic català de la «Verge amb casulla» no es troba abans en l'art de la talla, sinó en pintura mural romànica de les valls pirinenques del nord-oest de Catalunya. L'ambient històric i cultural que pot justificar el desenvolupament i propgació d'aquest tipus de Verge serà analitzat en el context de la reforma religiosa dels segles XI i XII a Catalunya

Electronic Properties of Topological Materials: Optical Excitations in Moebius Conjugated Polymers

Electronic structures and optical excitations in Moebius conjugated polymers are studied theoretically. Periodic and Moebius boundary conditions are applied to the tight binding model of poly(para-phenylene), taking exciton effects into account. We discuss that oligomers with a few structural units are more effective than polymers for observations of effects of discrete wave numbers that are shifted by the change in boundary condition. Next, calculations of optical absorption spectra are reported. Certain components of optical absorption for an electric field perpendicular to the polymer axis mix with absorption spectra for an electric field parallel to the polymer axis. Therefore, the polarization dependences of an electric field of light enable us to detect whether conjugated polymers have the Moebius boundary.Comment: 10 pages, 6 figures, to be published in J. Phys. Soc. Jpn., Vol. 74 No. 2 (February, 2005), Letter sectio

Grain size distributions of fault rocks: a comparison between experimentally and naturally deformed granitoids.

International audienceWe have investigated the grain size distribution (GSD) of granitoid fault rock by comparing experimentally produced gouge with fault rock from the Nojima Fault Zone. Triaxial experiments were carried out on wet and dry intact samples of Verzasca Gneiss at T = 300 and 500°C, Pc = 500 and 1030 MPa, ε = 0.013-1.6 x 10-4s-1. The GSD has been determined from SEM-micrographs and is characterized by the slope, D, of its log(frequency)-log(radius) histogram. The GSD is not fractal; we observe two slopes for all GSDs. The larger grains in experimentally deformed samples have a D value, D>, of 2.04 and 2.26 for feldspar and quartz gouge. Cracked grains yield values of D = 1.5-1.6.Increasing the confining pressure or temperature decreases the D-value. For grains smaller than ~2 μm another D-value, D = 2.02 for gouge and 1.64 for cracked grains; D< = 0.97. Grain size reduction in fault zones develops by a two-stage process: rupturing creates cracked grains; further displacement of fragments causes further comminution by wear and attrition. Cracked grains have been used to calculate the surface energy associated with faulting; it follows that this energy forms a small fraction in the total energy-budget of earthquakes

Dislocation creep of dry quartz

International audienceSmall-scale shear zones within the Permian Truzzo meta-granite developed during the Alpine orogeny at amphibolite facies conditions. In these shear zones magmatic quartz deformed by dislocation creep and recrystallized dynamically by grain boundary migration with minor subgrain rotation recrystallization to a grain size of around 250–750 μm, consistent with flow at low differential stresses. Fourier transform infrared (FTIR) spectroscopy reveals very low water contents in the interior of recrystallized grains (in the form of discrete OH peaks, ~20 H/10 6 Si and very little broad band absorption, <100 H/10 6 Si). The spectral characteristics are comparable to those of dry Brazil quartz. In FTIR spectra, magmatic quartz grains show a broad absorption band related with high water concentrations only in those areas where fluid inclusions are present while other areas are dry. Drainage of fluid inclusions and synkinematic growth of hydrous minerals indicates that a hydrous fluid has been available during deformation. Loss of intragranular water during grain boundary migration recrystallization did not result in a microstructure indicative of hardening. These FTIR measurements provide the first evidence that quartz with extremely low intragranular water contents can deform in nature by dislocation creep at low differential stresses. Low intragranular water contents in naturally deformed quartz may not be necessarily indicative of a high strength, and the results are contrary to implications taken from deformation experiments where very high water contents are required to allow dislocation creep in quartz. It is suggested that dislocation creep of quartz in the Truzzo meta-granite is possible to occur at low differential stresses because sufficient amounts of intergranular water ensure a high recovery rate by grain boundary migration while the absence of significant amounts of intragranular water is not crucial at natural conditions

Genetic origins of social networks in rhesus macaques

This is the final version of the article. Available from the publisher via the DOI in this record.Sociality is believed to have evolved as a strategy for animals to cope with their environments. Yet the genetic basis of sociality remains unclear. Here we provide evidence that social network tendencies are heritable in a gregarious primate. The tendency for rhesus macaques, Macaca mulatta, to be tied affiliatively to others via connections mediated by their social partners - analogous to friends of friends in people - demonstrated additive genetic variance. Affiliative tendencies were predicted by genetic variation at two loci involved in serotonergic signalling, although this result did not withstand correction for multiple tests. Aggressive tendencies were also heritable and were related to reproductive output, a fitness proxy. Our findings suggest that, like humans, the skills and temperaments that shape the formation of multi-agent relationships have a genetic basis in nonhuman primates, and, as such, begin to fill the gaps in our understanding of the genetic basis of sociality.We thank Bonn Aure, Jacqueline Buhl, Monica Carlson, Matthew McConnell, Elizabeth Maldonado, David Paulsen, Cecilia Penedo & the Caribbean Primate Research Center (CPRC) for assistance, and Roger Mundry for the use of PSAM software. The authors were supported by NIMH grant R01-MH089484, an Incubator Award from the Duke Institute for Brain Sciences, and a Duke Center for Interdisciplinary Decision Sciences Fellowship to LJNB. The CPRC is supported by grant 8-P40 OD012217-25 from the National Center for Research Resources (NCRR) and the Office of Research Infrastructure Programs (ORIP) of the National Institutes of Health

International STEM Achievement: Not a Zero-Sum Game

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Issue Brief: Building Public Will to Achieve Access to Health

This brief provides an overview of the concept of public will building, and looks at how it may serve as an important means to help achieve access to health. As well as describing actions and experiences within each phase of building public will, the brief also provides a case study of how this approach has impacted environmental awareness, another complex issue