Novel anisotropic continuum-discrete damage model capable of representing localized failure of massive structures. Part II: identification from tests under heterogeneous stress field

In Part I of this paper we have presented a simple model capable of describing the localized failure of a massive structure. In this part, we discuss the identification of the model parameters from two kinds of experiments: a uniaxial tensile test and a three-point bending test. The former is used only for illustration of material parameter response dependence, and we focus mostly upon the latter, discussing the inverse optimization problem for which the specimen is subjected to a heterogeneous stress field.Comment: 18 pages, 12 figures, 6 table

Response of a supersonic boundary layer to a compression corner

On the basis of direct numerical simulations of rapidly compressed turbulence, Zeman and Coleman have developed a model to represent rapid directional compression contribution to the pressure dilatation term in the turbulent kinetic energy equation. The model has been implemented in the CFD code for simulation of supersonic compression corner flow with an extended separated region. The computational results have shown a significant improvement with respect to the baseline solution given by the standard k- epsilon turbulence model which does not contain any compressibility corrections

Microstructural enrichment functions based on stochastic Wang tilings

This paper presents an approach to constructing microstructural enrichment functions to local fields in non-periodic heterogeneous materials with applications in Partition of Unity and Hybrid Finite Element schemes. It is based on a concept of aperiodic tilings by the Wang tiles, designed to produce microstructures morphologically similar to original media and enrichment functions that satisfy the underlying governing equations. An appealing feature of this approach is that the enrichment functions are defined only on a small set of square tiles and extended to larger domains by an inexpensive stochastic tiling algorithm in a non-periodic manner. Feasibility of the proposed methodology is demonstrated on constructions of stress enrichment functions for two-dimensional mono-disperse particulate media.Comment: 27 pages, 12 figures; v2: completely re-written after the first revie

Rapid differentiation of Francisella species and subspecies by fluorescent in situ hybridization targeting the 23S rRNA

<p>Abstract</p> <p>Background</p> <p><it>Francisella (F.) tularensis </it>is the causative agent of tularemia. Due to its low infectious dose, ease of dissemination and high case fatality rate, <it>F. tularensis </it>was the subject in diverse biological weapons programs and is among the top six agents with high potential if misused in bioterrorism. Microbiological diagnosis is cumbersome and time-consuming. Methods for the direct detection of the pathogen (immunofluorescence, PCR) have been developed but are restricted to reference laboratories.</p> <p>Results</p> <p>The complete 23S rRNA genes of representative strains of <it>F. philomiragia </it>and all subspecies of <it>F. tularensis </it>were sequenced. Single nucleotide polymorphisms on species and subspecies level were confirmed by partial amplification and sequencing of 24 additional strains. Fluorescent In Situ Hybridization (FISH) assays were established using species- and subspecies-specific probes.</p> <p>Different FISH protocols allowed the positive identification of all 4 <it>F. philomiragia </it>strains, and more than 40 <it>F. tularensis </it>strains tested. By combination of different probes, it was possible to differentiate the <it>F. tularensis </it>subspecies <it>holarctica, tularensis, mediasiatica </it>and <it>novicida</it>. No cross reactivity with strains of 71 clinically relevant bacterial species was observed. FISH was also successfully applied to detect different <it>F. tularensis </it>strains in infected cells or tissue samples. In blood culture systems spiked with <it>F. tularensis</it>, bacterial cells of different subspecies could be separated within single samples.</p> <p>Conclusion</p> <p>We could show that FISH targeting the 23S rRNA gene is a rapid and versatile method for the identification and differentiation of <it>F. tularensis </it>isolates from both laboratory cultures and clinical samples.</p

The neural correlates of visual imagery vividness - an fMRI study and literature review

This is the final version of the article. Available from Elsevier via the DOI in this record.Using the Vividness of Visual Imagery Questionnaire we selected 14 high-scoring and 15 low-scoring healthy participants from an initial sample of 111 undergraduates. The two groups were matched on measures of age, IQ, memory and mood but differed significantly in imagery vividness. We used fMRI to examine brain activation while participants looked at, or later imagined, famous faces and famous buildings. Group comparison revealed that the low-vividness group activated a more widespread set of brain regions while visualising than the high-vividness group. Parametric analysis of brain activation in relation to imagery vividness across the entire group of participants revealed distinct patterns of positive and negative correlation. In particular, several posterior cortical regions show a positive correlation with imagery vividness: regions of the fusiform gyrus, posterior cingulate and parahippocampal gyri (BAs 19, 29, 31 and 36) displayed exclusively positive correlations. By contrast several frontal regions including parts of anterior cingulate cortex (BA 24) and inferior frontal gyrus (BAs 44 and 47), as well as the insula (BA 13), auditory cortex (BA 41) and early visual cortices (BAs 17 and 18) displayed exclusively negative correlations. We discuss these results in relation to a previous, functional imaging study of a clinical case of ‘blind imagination’, and to the existing literature on the functional imaging correlates of imagery vividness and related phenomena in visual and other domains.Jonathan Fulford’s salary was supported via an NIHR grant