Experimental investigation of the air blast performance of hybrid composite skinned sandwich panels with X-ray micro-CT damage assessment

This research investigates the performance of interlaminar hybrid composites as the skins of composite sandwich panels under blast loading with the aim of promoting delamination between dissimilar plies for energy absorption. The deformation of the composite panels was captured using high-speed digital image correlation (DIC). High-speed full-field DIC enables failure to be captured at the moment it occurs across the entire panel. X-ray micro-CT imaging was used to assess the post-blast damage sustained by particular areas of interest from each panel, which were selected based on DIC results. The combination of full-field DIC and detailed X-ray micro-CT scanning enabled a unique comparison of both the global and localised blast resilience of hybrid and conventional composite sandwich panels to be performed. Following a single blast load, the extent of damage to the Hybrid-3B skinned sandwich panel was found to lie between that of GFRP and CFRP skinned sandwich panels. X-ray micro-CT scanning of these panels reveals that there is no continuous damage path through the skin thickness of Hybrid-3B, whereas the GFRP and CFRP panels sustain damage in every ply. Following repeat blast loading, the Hybrid-4 skinned sandwich panel suffered from a front skin crack spanning the length of the panel. Post-blast compressive strength testing reveals that this skin crack and resulting core crack acted as a stress relief, limiting the damage sustained elsewhere in the panel. It was concluded that Hybrid-3B results in a good trade-off between strength and stiffness and is advantageous over conventional CFRP and GFRP panels under a single blast load. Under repeated loading Hybrid-4 offers advantages over Hybrid-3B. Finally, the design of the support structure can significantly aid in blast resilience, and, a holistic approach considering both panels and support should be taken when designing for blast resilience

Estimation of the correlation coefficient using the Bayesian Approach and its applications for epidemiologic research

BACKGROUND: The Bayesian approach is one alternative for estimating correlation coefficients in which knowledge from previous studies is incorporated to improve estimation. The purpose of this paper is to illustrate the utility of the Bayesian approach for estimating correlations using prior knowledge. METHODS: The use of the hyperbolic tangent transformation (ρ = tanh ξ and r = tanh z) enables the investigator to take advantage of the conjugate properties of the normal distribution, which are expressed by combining correlation coefficients from different studies. CONCLUSIONS: One of the strengths of the proposed method is that the calculations are simple but the accuracy is maintained. Like meta-analysis, it can be seen as a method to combine different correlations from different studies

Mutation at the Evi1 locus in Junbo mice causes susceptibility to otitis media

Otitis media ( OM), inflammation of the middle ear, remains the most common cause of hearing impairment in children. It is also the most common cause of surgery in children in the developed world. There is evidence from studies of the human population and mouse models that there is a significant genetic component predisposing to OM, yet nothing is known about the underlying genetic pathways involved in humans. We identified an N-ethyl-N-nitrosourea-induced dominant mouse mutant Junbo with hearing loss due to chronic suppurative OM and otorrhea. This develops from acute OM that arises spontaneously in the postnatal period, with the age of onset and early severity dependent on the microbiological status of the mice and their air quality. We have identified the causal mutation, a missense change in the C-terminal zinc finger region of the transcription factor Evi1. This protein is expressed in middle ear basal epithelial cells, fibroblasts, and neutrophil leukocytes at postnatal day 13 and 21 when inflammatory changes are underway. The identification and characterization of the Junbo mutant elaborates a novel role for Evi1 in mammalian disease and implicates a new pathway in genetic predisposition to OM

Encoding of Temporal Information by Timing, Rate, and Place in Cat Auditory Cortex

A central goal in auditory neuroscience is to understand the neural coding of species-specific communication and human speech sounds. Low-rate repetitive sounds are elemental features of communication sounds, and core auditory cortical regions have been implicated in processing these information-bearing elements. Repetitive sounds could be encoded by at least three neural response properties: 1) the event-locked spike-timing precision, 2) the mean firing rate, and 3) the interspike interval (ISI). To determine how well these response aspects capture information about the repetition rate stimulus, we measured local group responses of cortical neurons in cat anterior auditory field (AAF) to click trains and calculated their mutual information based on these different codes. ISIs of the multiunit responses carried substantially higher information about low repetition rates than either spike-timing precision or firing rate. Combining firing rate and ISI codes was synergistic and captured modestly more repetition information. Spatial distribution analyses showed distinct local clustering properties for each encoding scheme for repetition information indicative of a place code. Diversity in local processing emphasis and distribution of different repetition rate codes across AAF may give rise to concurrent feed-forward processing streams that contribute differently to higher-order sound analysis

Ancestral State Reconstruction Reveals Rampant Homoplasy of Diagnostic Morphological Characters in Urticaceae, Conflicting with Current Classification Schemes

Urticaceae is a family with more than 2000 species, which contains remarkable morphological diversity. It has undergone many taxonomic reorganizations, and is currently the subject of further systematic studies. To gain more resolution in systematic studies and to better understand the general patterns of character evolution in Urticaceae, based on our previous phylogeny including 169 accessions comprising 122 species across 47 Urticaceae genera, we examined 19 diagnostic characters, and analysed these employing both maximum-parsimony and maximum-likelihood approaches. Our results revealed that 16 characters exhibited multiple state changes within the family, with ten exhibiting >eight changes and three exhibiting between 28 and 40. Morphological synapomorphies were identified for many clades, but the diagnostic value of these was often limited due to reversals within the clade and/or homoplasies elsewhere. Recognition of the four clades comprising the family at subfamily level can be supported by a small number carefully chosen defining traits for each. Several non-monophyletic genera appear to be defined only by characters that are plesiomorphic within their clades, and more detailed work would be valuable to find defining traits for monophyletic clades within these. Some character evolution may be attributed to adaptive evolution in Urticaceae due to shifts in habitat or vegetation type. This study demonstrated the value of using phylogeny to trace character evolution, and determine the relative importance of morphological traits for classification

Thigh-length compression stockings and DVT after stroke

Controversy exists as to whether neoadjuvant chemotherapy improves survival in patients with invasive bladder cancer, despite randomised controlled trials of more than 3000 patients. We undertook a systematic review and meta-analysis to assess the effect of such treatment on survival in patients with this disease