Deformation microstructures of Barre granite: An optical, Sem and Tem study

New scanning electron microscope techniques have been developed for characterizing ductile deformation microstructures in felsic rocks. In addition, the thermomechanical history of the macroscopically undeformed Barre granite (Vermont, U.S.A.) has been reconstructed based on examination of deformation microstructures using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The microstructures reveal three distinct events: 1. (1) a low-stress, high-temperature event that produced subgrains in feldspars, and subgrains and recrystallized grains in quartz;2. (2) a high-stress, low-temperature event that produced a high dislocation density in quartz and feldspars; and3. (3) a lowest-temperature event that produced cracks, oriented primarily along cleavage planes in feldspars, and parallel to the macroscopic rift in quartz. The first two events are believed to reflect various stages in the intrusion and cooling history of the pluton, and the last may be related to the last stages of cooling, or to later tectonism.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26275/1/0000360.pd

Novel Loci for Adiponectin Levels and Their Influence on Type 2 Diabetes and Metabolic Traits : A Multi-Ethnic Meta-Analysis of 45,891 Individuals

J. Kaprio, S. Ripatti ja M.-L. Lokki työryhmien jäseniä.Peer reviewe

Anisotropic yielding of rocks at high temperatures and pressures; Annual Progress Report, 1988-1989

The experimental results we have obtained on Four-Mile gneiss have demonstrated that the yield behavior of quartzo-feldspathic rocks containing only a small percentage (10%) of mica can be markedly anisotropic, provided the mica minerals exhibit a strong crystallographic preferred orientation. Samples of gneiss oriented such that resolved shear stresses on the foliation plane are large are considerably weaker than granites of similar grain size and composition, and this weakness is attributed to enhanced nucleation of microcracks in quartz and feldspar adjacent to mica grains that are suitably oriented for slip. We expect the yield behavior of rocks containing a higher proportion of phyllosilicates to be influenced by the strongly anisotropic nature of these minerals as well, although the strengths, temperature and pressure dependencies, and flow-controlling mechanisms in such rocks may be significantly different

Anisotropic yielding of rocks at high temperatures and pressures

Results to date are: All of the starting materials for the three year project have been collected. Included in our collection are relatively fine-grained, fresh, oriented blocks of schist, gneiss, and micaceous quartzite with well-defined foliations and lineations as well as granite blocks oriented with respect to the principal quarrying orientations, the rift, grain, and hardway. A suite of samples has also been collected from an exposed granite stock and surrounding country rocks in order to evaluate the strengths and distribution of fabrics which may be encountered while drilling. These fabrics appear to be directly related to the forceful emplacement of the pluton. The literature on the mechanics of intrusion has been reviewed with regard to strain gradients and foliation development associated with diapiric flow. This information will be used to evaluate flow of varying fabrics on yield criteria within and surrounding magma chambers. Twenty-three successful experiments have been performed on samples of gneiss cored along six different orientations at temperatures ranging from 25{degrees} to 700{degrees}C. These experiments include extension tests, unconfined compression tests, and compression tests performed at P{sub c} = 100 MPa. Theoretical yield conditions for anisotropic materials have been reviewed and the assumptions upon which they are based probed. These yield conditions will ultimately be used to fit our data on gneiss, and the other foliated rocks under investigation. Two abstracts have been published and oral presentations made at the 1987 Fall Meeting of the American Geophysical Union, based upon our previous DOE-sponsored work on tensile fracturing of quartzite and related work on semi-brittle deformation of granitic rocks. 21 refs., 12 figs., 2 tabs

Mechanical properties and modeling of seal-forming lithologies

Both rocksalt and shale lithologies are actively deformed in response to gravitational loads associated with deposition, and both form effective seals to petroleum and natural gas. Thus, the shapes of seal-forming units, and the nature of fractures and faults that may breach them depend upon either the mechanical properties of salt or those of shale, and the loading histories to which they have been subjected. The objectives of this research include the determination of the mechanical properties under controlled conditions of well-characterized shales, and the numerical modeling of rocksalt (and eventually shale) formations using laboratory-based rheologies. Progress has been made towards these goals over this project period, both in our experimental program on shale deformation and model development for the growth of salt diapirs. The mechanical anisotropy of an illite-bearing shale from Louisiana has been determined and related to the preferred orientation and distribution of clays. Its strength in the absence of pore fluids has been determined at confining pressures of up to 250 MPa and at high pressure we have investigated the effects of deformation rate and temperature. A numerical finite difference code has been developed to solve the incompressible Navier-Stokes equations and validated using a two- layer linear viscous model for which analytic solutions are available. Although the code has only been validated for the linear viscous case, it is capable of solving for highly nonlinear constitutive laws as well as solving for arbitrary interfaces between the salt and overburden

Blood and islet phenotypes indicate immunological heterogeneity in type 1 diabetes

Studies in type 1 diabetes indicate potential disease heterogeneity, notably in the rate of β-cell loss, responsiveness to immunotherapies, and, in limited studies, islet pathology. We sought evidence for different immunological phenotypes using two approaches. First, we defined blood autoimmune response phenotypes by combinatorial, multiparameter analysis of autoantibodies and autoreactive T-cell responses in 33 children/adolescents with newly diagnosed diabetes. Multidimensional cluster analysis showed two equal-sized patient agglomerations characterized by proinflammatory (interferon-γ–positive, multiautoantibody-positive) and partially regulated (interleukin-10–positive, pauci-autoantibody–positive) responses. Multiautoantibody-positive nondiabetic siblings at high risk of disease progression showed similar clustering. Additionally, pancreas samples obtained post mortem from a separate cohort of 21 children/adolescents with recently diagnosed type 1 diabetes were examined immunohistologically. This revealed two distinct types of insulitic lesions distinguishable by the degree of cellular infiltrate and presence of B cells that we termed “hyper-immune CD20Hi” and “pauci-immune CD20Lo.” Of note, subjects had only one infiltration phenotype and were partitioned by this into two equal-sized groups that differed significantly by age at diagnosis, with hyper-immune CD20Hi subjects being 5 years younger. These data indicate potentially related islet and blood autoimmune response phenotypes that coincide with and precede disease. We conclude that different immunopathological processes (endotypes) may underlie type 1 diabetes, carrying important implications for treatment and prevention strategies

DNA methylation of lipid-related genes affects blood lipid levels: A genome-wide screen.

Background: Epigenetic mechanisms might be involved in the regulation of interindividual lipid level variability and thus may contribute to the cardiovascular risk profile. Aim of this study was to systematically investigate the association between genome-wide DNA methylation in whole blood and serum lipid levels of HDL-C, LDL-C, triglycerides (TG) and total cholesterol (TC).    Results: Genome-wide DNA methylation patterns were determined in blood samples of 1776 subjects of the KORA F4 cohort using the Infinium HumanMethylation450 BeadChip (Illumina). Associations between DNA methylation and lipid levels were analyzed using linear mixed-effects models with lipid levels as response. To correct for multiple comparisons, a genome-wide significance level of 1.1E-07 was used according to the Bonferroni procedure. We identified eleven lipid-related CpGs annotated to several genes including ABCG1. One CpG site located in ABCG1 was associated in opposite directions with both HDL-C ( coefficient=0.049, p=8.26E-17) and TG levels (=0.070, p=1.21E-27). Nine of the associations were confirmed by replication in KORA F3 (N=499) and InCHIANTI (N=472). Associations between TG levels and CpGs of two genes were also found in adipose but not in skin tissue of the MuTHER cohort, indicating tissue specificity. Expression analysis revealed that the association between ABCG1 methylation and lipid levels is partly mediated by the expression of ABCG1. The identified association between ABCG1 methylation and ABCG1 mRNA levels is possibly based on methylation-dependent transcription factor binding as observed in electrophoretic mobility shift assays. DNA methylation of ABCG1 was also associated with previous myocardial infarction in KORA F4 (odds ratio 1.15, 95%CI=1.06-1.25).     Conclusion: We found associations between DNA methylation and lipid levels for genes contributing to the modulation of cholesterol and fatty acid metabolism. The results indicate an epigenetic impact on metabolic regulation in humans and give new insights into the complex picture of lipid-related complex diseases