Multi-level analysis of localisation problems

Localisation processes, such as shear banding and necking, have been investigated following a macroscopic and a microscopic approach. Both approaches have been formulated within a finite deformation plasticity framework. Additional terms have been used to regularise the problem and solve mesh dependency. In the macroscopic model viscosity is introduced as a means to control the thickness of the shear band, while in the microscopic model the nonlocal interaction of dislocations acts as a stabiliser. The micro-mechanical model is formulated in a crystal plasticity framework. A diffusion term that represents cross-slip of dislocations is included in the evolution equations for dislocation densities. The effect of the viscous term (macro-model) and the diffusion-like term (micro-model) in the constitutive relation on the resulting formation of localised shear modes is studied. An analysis of a strip in tension oriented for multiple slip is presented for both models

AUTOTEM - Automated geometry meshing and heat conduction calculation

Temperature distribution for an arbitrary irregular body is calculated by AUTOTEM, which generates required input data automatically by computer. Temperature distribution is calculated for a two-dimensional plane section in /x,y/ coordinates or for an axisymmetric irregular body in /r,z/ coordinates

Phenotypic and functional analysis of positive selection in the gamma/delta T cell lineage.

Recent evidence suggests that T cells expressing gamma/delta antigen receptors (T cell receptor [TCR]) are subject to positive selection during development. We have shown that T cells expressing a class I major histocompatibility complex (MHC)-specific gamma/delta TCR transgene (tg) are not positively selected in class I MHC-deficient, beta 2-microglobulin (beta 2m) gene knockout mice (tg+ beta 2m-). In this report, we examine phenotypic and functional parameters of gamma/delta positive selection in this transgenic model system. TCR-gamma/delta tg+ thymocytes of mature surface phenotype (heat stable antigen-, CD5hi) were found in beta 2m+ but not in beta 2m- mice. Moreover, subsets of tg+ thymocytes with the phenotype of activated T cells (interleukin [IL]2R+, CD44hi, or Mel-14lo) were also present only in the beta 2m+ mice. Cyclosporine A, which blocks positive selection of TCR-alpha/beta T cells, also inhibited gamma/delta tg+ T cell development. These results support the idea that positive selection of TCR-gamma/delta requires active TCR-mediated signal transduction. Whereas tg+ beta 2m+ thymocytes produced IL-2 and proliferated when stimulated by alloantigen, TCR engagement of tg+ beta 2m- thymocytes by antigen induced IL-2R expression but was uncoupled from the signal transduction pathway leading to IL-2 production and autocrine proliferation. Overall, these results demonstrate significant parallels between gamma/delta and alpha/beta lineage development, and suggest a general role for TCR signaling in thymic maturation

Spin Correlations in the Two-Dimensional Spin-5/2 Heisenberg Antiferromagnet Rb2MnF4

We report a neutron scattering study of the instantaneous spin correlations in the two-dimensional spin S=5/2 square-lattice Heisenberg antiferromagnet Rb_2MnF_4. The measured correlation lengths are quantitatively described, with no adjustable parameters, by high-temperature series expansion results and by a theory based on the quantum self-consistent harmonic approximation. Conversely, we find that the data, which cover the range from about 1 to 50 lattice constants, are outside of the regime corresponding to renormalized classical behavior of the quantum non-linear sigma model. In addition, we observe a crossover from Heisenberg to Ising critical behavior near the Neel temperature; this crossover is well described by a mean-field model with no adjustable parameters.Comment: 8 pages, LaTeX, with 6 included EPS figures, submitted to EPJ

A Corpus-Based, Pilot Study of Lexical Stress Variation in American English

Phonological free variation describes the phenomenon of there being more than one pronunciation for a word without any change in meaning (e.g. because, schedule, vehicle). The term also applies to words that exhibit different stress patterns (e.g. academic, resources, comparable) with no change in meaning or grammatical category. A corpus-based analysis of free variation is a useful tool for testing the validity of surveys of speakers' pronunciation preferences for certain variants. The current paper presents the results of a corpus-based pilot study of American English, in an attempt to replicate Mompéan's 2009 study of British English

Qualified Immunity and Statutory Interpretation: A Response to William Baude

In his article, Is Qualified Immunity Unlawful?, Professor Baude argues that the doctrine of qualified immunity under section 1983 is unlawful because the doctrine did not exist at the time section 1983 was enacted. We disagree. Section 1983 is a common law statute. Consequently, its meaning and application was not fixed at the time of original passage. In this article, we explain why. Although we are sympathetic to Professor Baude’s implicit policy-based critique of the doctrine of qualified immunity, we believe his analysis is flawed. The better and more likely way to improve the doctrine is through the common law method

Evolution of superconductivity by oxygen annealing in FeTe0.8S0.2

Oxygen annealing dramatically improved the superconducting properties of solid-state-reacted FeTe0.8S0.2, which showed only a broad onset of superconducting transition just after the synthesis. The zero resistivity appeared and reached 8.5 K by the oxygen annealing at 200\degree C. The superconducting volume fraction was also enhanced from 0 to almost 100%. The lattice constants were compressed by the oxygen annealing, indicating that the evolution of bulk superconductivity in FeTe0.8S0.2 was correlated to the shrinkage of lattice.Comment: 13 pages, 6 figure

Numerical simulation of ripple formation

River morphodynamics and sediment transportMechanics of sediment transpor

Multifractal Scaling of Thermally-Activated Rupture Processes

We propose a ``multifractal stress activation'' model combining thermally activated rupture and long memory stress relaxation, which predicts that seismic decay rates after mainshocks follow the Omori law $\sim 1/t^p$ with exponents $p$ linearly increasing with the magnitude $M_L$ of the mainshock and the inverse temperature. We carefully test this prediction on earthquake sequences in the Southern California Earthquake catalog: we find power law relaxations of seismic sequences triggered by mainshocks with exponents $p$ increasing with the mainshock magnitude by approximately $0.1-0.15$ for each magnitude unit increase, from $p(M_L=3) \approx 0.6$ to $p(M_L=7) \approx 1.1$, in good agreement with the prediction of the multifractal model.Comment: four pages and 2 figure

Local Structure and It's Effect on The Ferromagnetic Properties of La0.5_{0.5}Sr0.5_{0.5}CoO3_3 thin films}

We have used high-resolution Extended X-ray Absorption Fine-Structure and diffraction techniques to measure the local structure of strained La$_{0.5}$Sr$_{0.5}$CoO$_3$ films under compression and tension. The lattice mismatch strain in these compounds affects both the bond lengths and the bond angles, though the larger effect on the bandwidth is due to the bond length changes. The popular double exchange model for ferromagnetism in these compounds provides a correct qualitative description of the changes in Curie temperature $T_C$, but quantitatively underestimates the changes. A microscopic model for ferromagnetism that provides a much stronger dependence on the structural distortions is needed.Comment: 4 pages, 4 figure