Resistance of Carbon Fibre Reinforced Composites to Quasi-static and Ballistic Perforation

The failure mechanisms, as well as the indentation and penetration resistance, of carbon fibre reinforced plastic (CFRP) cross-ply laminates were investigated under quasi-static and ballistic loading. In this thesis, the two most prominent failure modes were indirect tension and shear plugging. To characterise the indirect tension mechanism, CFRP cross-ply coupons with various matrix shear strengths were subjected to uniaxial out-of-plane compression between lubricated platens, while CFRP cross-ply beams were subjected to quasi-static indentation between a flat bottom indentor and a lubricated back support. The out-of-plane compressive strength was accurately predicted by finite element simulations and analytical models. To characterise the shear plugging mechanism, quasi-static cropping tests were performed on CFRP cross-ply beams. A beam configuration was selected to allow for ease of identifying the failure mechanisms. The investigation was extended to consider the effect of matrix shear strength on the ballistic performance of simply supported CFRP cross-ply beams impacted by a flat projectile. Laminates with high matrix shear strength failed by shear plugging, and the penetration velocity increased with decreasing matrix shear strength. As the matrix shear strength decreased further, the failure mode switched to indirect tension and subsequently the penetration velocity remained elevated, independent of the matrix shear strength. Having established that shear plugging is associated with low impact resistance, a new type of bilayer CFRP composite (comprising one low and one high matrix shear strength layer) was developed with the intent of suppressing this shear plugging mode. The ballistic penetration resistance of the bilayer beams was compared to that of the above monolithic CFRP beams using the same ballistic set-up. It was observed that the shear plugging mode in the high strength layer was suppressed when the layer was placed at the distal face; failure switched to a back face tensile mode, and the impact resistance was improved. The investigation was extended to a more realistic impact environment: CFRP cross-ply laminates in a plate configuration were perforated by a steel ball. Specimens were tested under quasi-static and ballistic loading with either a back-supported condition (simulating a thick laminate) or an edge-clamped condition. The CFRP plates failed by indirect tension when back-supported but failed by shear plugging when edge-clamped. It was found that the addition of a protective aluminium alloy layer did not alter the failure mechanism of the CFRP, but did produce a load spreading effect that increased the penetration resistance.The tuition of this author was fully sponsored by the Croucher Foundation and the Cambridge Commonwealth, European & International Trust through the Cambridge Croucher International Scholarshi

Learning-based auditory encoding for robust speech recognition

This paper describes ways of speeding up the optimization process for learning physiologically-motivated components of a feature computation module directly from data. During training, word lattices generated by the speech decoder and conjugate gradient descent were included to train the parameters of logistic functions in a fashion that maximizes the a posteriori probability of the correct class in the training data. These functions represent the rate-level nonlinearities found in most mammalian auditory systems. Experiments conducted using the CMU SPHINX-III system on the DARPA Resource Management and Wall Street Journal tasks show that the use of discriminative training to estimate the shape of the rate-level nonlinearity provides better recognition accuracy in the presence of background noise than traditional procedures which do not employ learning. More importantly, the inclusion of conjugate gradient descent optimization and a word lattice to reduce the number of hypotheses considered greatly increases the training speed, which makes training with much more complicated models possible. Index Terms — automatic speech recognition, discriminative training, auditory models, data analysis 1

TRIP/NOPO E3 Ubiquitin Ligase Promotes Ubiquitylation of DNA Polymerase η

We previously identified a Drosophila maternal effect-lethal mutant named ‘no poles’ (nopo). Embryos from nopo females undergo mitotic arrest with barrel-shaped, acentrosomal spindles during the rapid cycles of syncytial embryogenesis because of activation of a Chk2-mediated DNA checkpoint. NOPO is the Drosophila homolog of human TNF receptor associated factor (TRAF)-interacting protein (TRIP), which has been implicated in TNF signaling. NOPO and TRIP contain RING domains closely resembling those of known E3 ubiquitin ligases. We herein sought to elucidate the mechanism by which TRIP/NOPO promotes genomic stability by performing a yeast two-hybrid screen to identify potential substrates/interactors. We identified members of the Y-family of DNA polymerases that facilitate replicative bypass of damaged DNA (translesion synthesis) as TRIP interactors. We show that TRIP and NOPO co-immunoprecipitate with human and Drosophila Polη, respectively, from cultured cells. We generated a null mutation in Drosophila Polη (dPolη) and found that dPolη-derived embryos have increased sensitivity to ultraviolet irradiation and exhibit nopo-like mitotic spindle defects. dPolη and nopo interact genetically in that overexpression of dPolηn hypomorphic nopo-derived embryos suppresses nopo phenotypes. We observed enhanced ubiquitylation of Polη by TRIP and NOPO E3 ligases in human cells and Drosophila embryos, respectively, and show that TRIP promotes hPolη localization to nuclear foci in human cells. We present a model in which TRIP/NOPO ubiquitylates Polη to positively regulate its activity in translesion synthesis

Identifying gene network patterns and associated cellular immune responses in children with or without nut allergy

Background: Although evidence suggests that the immune system plays a key role in the pathophysiology of nut allergy, the precise immunological mechanisms of nut allergy have not been systematically investigated. The aim of the present study was to identify gene network patterns and associated cellular immune responses in children with or without nut allergy. Methods: Transcriptome profiling of whole blood cells was compared between children with and without nut allergy. Three genes were selected to be validated on a larger cohort of samples (n = 86) by reverse transcription-polymerase chain reactions (RT-qPCR). The composition of immune cells was inferred from the transcriptomic data using the CIBERSORTx algorithm. A co-expression network was constructed employing weighted gene co-expression network analysis (WGCNA) on the top 5000 most variable transcripts. The modules were interrogated with pathway analysis tools (InnateDB) and correlated with clinical phenotypes and cellular immune responses. Results: Proportions of neutrophils were positively correlated and CD4+ T-cells and regulatory T-cells (Tregs) were negatively correlated with modules of nut allergy. We also identified 2 upregulated genes, namely Interferon Induced With Helicase C Domain 1 (IFIH1), DNA damage-regulated autophagy modulator 1 (DRAM1) and a downregulated gene Zinc Finger Protein 512B (ZNF512B) as hub genes for nut allergy. Further pathway analysis showed enrichment of type 1 interferon signalling in nut allergy. Conclusions: Our findings suggest that upregulation of type 1 interferon signalling and neutrophil responses and downregulation of CD4+ T-cells and Tregs are features of the pathogenesis of nut allergy

The moving boundaries of social heat: gambling in rural China

Whilst gambling for money was prohibited during the Maoist era, since the 1980s it has become very common in many rural areas of central China. It is often the major communal activity in many villages, a focus point of daily gossip and an object of government campaigns. I describe several forms of gambling common in Bashan Township, Eastern Hubei Province, and relate them to local discourses on capability/skill and luck/fate. Gambling reproduces ‘social heat’, which is a desired form of social effervescence as long as it remains within certain boundaries. But the boundaries of accepted gambling and social heat in local sociality as well as those given in official representations and state discourse, are contested, and both stand in an ambiguous relationship to each other; a relationship that is described in terms of ‘cultural intimacy’. Using medium-range concepts such as ‘social heat’ and ‘cultural intimacy’ the article attempts to avoid the pitfalls of totalizing approaches which explain popular gambling as consequence of or resistance to ‘neoliberalism’

Plasmodium falciparum malaria importation from Africa to China and its mortality: an analysis of driving factors

Plasmodium falciparum malaria importation from Africa to China is rising with increasing Chinese overseas investment and international travel. Identifying networks and drivers of this phenomenon as well as the contributors to high case-fatality rate is a growing public health concern to enable efficient response. From 2011–2015, 8653?P. falciparum cases leading to 98 deaths (11.3 per 1000 cases) were imported from 41 sub-Saharan countries into China, with most cases (91.3%) occurring in labour-related Chinese travellers. Four strongly connected groupings of origin African countries with destination Chinese provinces were identified, and the number of imported cases was significantly associated with the volume of air passengers to China (P?=?0.006), parasite prevalence in Africa (P?<?0.001), and the amount of official development assistance from China (P?<?0.001) with investment in resource extraction having the strongest relationship with parasite importation. Risk factors for deaths from imported cases were related to the capacity of malaria diagnosis and diverse socioeconomic factors. The spatial heterogeneity uncovered, principal drivers explored, and risk factors for mortality found in the rising rates of P. falciparum malaria importation to China can serve to refine malaria elimination strategies and the management of cases, and high risk groups and regions should be targeted

Test of the Kolmogorov-Johnson-Mehl-Avrami picture of metastable decay in a model with microscopic dynamics

The Kolmogorov-Johnson-Mehl-Avrami (KJMA) theory for the time evolution of the order parameter in systems undergoing first-order phase transformations has been extended by Sekimoto to the level of two-point correlation functions. Here, this extended KJMA theory is applied to a kinetic Ising lattice-gas model, in which the elementary kinetic processes act on microscopic length and time scales. The theoretical framework is used to analyze data from extensive Monte Carlo simulations. The theory is inherently a mesoscopic continuum picture, and in principle it requires a large separation between the microscopic scales and the mesoscopic scales characteristic of the evolving two-phase structure. Nevertheless, we find excellent quantitative agreement with the simulations in a large parameter regime, extending remarkably far towards strong fields (large supersaturations) and correspondingly small nucleation barriers. The original KJMA theory permits direct measurement of the order parameter in the metastable phase, and using the extension to correlation functions one can also perform separate measurements of the nucleation rate and the average velocity of the convoluted interface between the metastable and stable phase regions. The values obtained for all three quantities are verified by other theoretical and computational methods. As these quantities are often difficult to measure directly during a process of phase transformation, data analysis using the extended KJMA theory may provide a useful experimental alternative.Comment: RevTex, 21 pages including 14 ps figures. Submitted to Phys. Rev. B. One misprint corrected in Eq.(C1

Coronavirus-positive Nasopharyngeal Aspirate as Predictor for Severe Acute Respiratory Syndrome Mortality

Severe acute respiratory syndrome (SARS) has caused a major epidemic worldwide. A novel coronavirus is deemed to be the causative agent. Early diagnosis can be made with reverse transcriptase-polymerase chain reaction (RT-PCR) of nasopharyngeal aspirate samples. We compared symptoms of 156 SARS-positive and 62 SARS-negative patients in Hong Kong; SARS was confirmed by RT-PCR. The RT-PCR–positive patients had significantly more shortness of breath, a lower lymphocyte count, and a lower lactate dehydrogenase level; they were also more likely to have bilateral and multifocal chest radiograph involvement, to be admitted to intensive care, to need mechanical ventilation, and to have higher mortality rates. By multivariate analysis, positive RT-PCR on nasopharyngeal aspirate samples was an independent predictor of death within 30 days