Microstructural characterisation of metallic shot peened and laser shock peened Ti–6Al–4V

A detailed analysis has been conducted of Ti–6Al–4V processed by metallic shot peening and laser shock peening. Analysis by incremental hole drilling, electron backscattered diffraction microscopy, transmission electron microscopy and transmission Kikuchi diffraction microscopy is evaluated and discussed. The results of this analysis highlight the very different dislocation structures in surfaces processed by these two techniques. Transmission Kikuchi diffraction also has been used to evaluate sub-grains generated by laser shock peening. A notable feature of material processed by laser shock peening is the almost complete absence of deformation twinning, contrasting with the frequent observation of extensive deformation twinning observed in the material processed by metallic shot peening.This work was supported by the Rolls-Royce plc/EPSRC strategic partnership under EP/H022309/1

Cr-Mo-V-W: A new refractory and transition metal high-entropy alloy system

Cr-Mo-V-W high-entropy alloy (HEA) is studied, with 2553 K equilibrium solidus and high Cr content to promote protective oxide scale formation, suggesting potential applications in hot, oxidising environments. Alloy Search and Predict (ASAP) and phase diagram calculations found a single phase, body-centred cubic (BCC) solid solution at elevated temperatures, across the range of compositions present within the system - uncommon for a HEA of refractory and transition metals. Density functional theory identified solubility of 22 at.% Cr at solidus temperature, with composition-dependent drive for segregation during cooling. An as-cast, BCC single-phase with the composition 31.3Cr-23.6Mo-26.4 V-18.7 W exhibiting dendritic microsegregation was verified

Generic Mechanism of Emergence of Amyloid Protofilaments from Disordered Oligomeric aggregates

The presence of oligomeric aggregates, which is often observed during the process of amyloid formation, has recently attracted much attention since it has been associated with neurodegenerative conditions such as Alzheimer's and Parkinson's diseases. We provide a description of a sequence-indepedent mechanism by which polypeptide chains aggregate by forming metastable oligomeric intermediate states prior to converting into fibrillar structures. Our results illustrate how the formation of ordered arrays of hydrogen bonds drives the formation of beta-sheets within the disordered oligomeric aggregates that form early under the effect of hydrophobic forces. Initially individual beta-sheets form with random orientations, which subsequently tend to align into protofilaments as their lengths increases. Our results suggest that amyloid aggregation represents an example of the Ostwald step rule of first order phase transitions by showing that ordered cross-beta structures emerge preferentially from disordered compact dynamical intermediate assemblies.Comment: 14 pages, 4 figure

Approximating Mexican highways with slime mould

Plasmodium of Physarum polycephalum is a single cell visible by unaided eye. During its foraging behavior the cell spans spatially distributed sources of nutrients with a protoplasmic network. Geometrical structure of the protoplasmic networks allows the plasmodium to optimize transport of nutrients between remote parts of its body. Assuming major Mexican cities are sources of nutrients how much structure of Physarum protoplasmic network correspond to structure of Mexican Federal highway network? To find an answer undertook a series of laboratory experiments with living Physarum polycephalum. We represent geographical locations of major cities by oat flakes, place a piece of plasmodium in Mexico city area, record the plasmodium's foraging behavior and extract topology of nutrient transport networks. Results of our experiments show that the protoplasmic network formed by Physarum is isomorphic, subject to limitations imposed, to a network of principle highways. Ideas and results of the paper may contribute towards future developments in bio-inspired road planning

Language learning and integration of adult Bhutanese refugees : an ethnographic study

This study sought a holistic and in-depth investigation of English language learning and integration experiences of a group of adult Bhutanese refugees in Australia. The Bhutanese refugees have settled since 2007 as new residents of their host country after two decades of expatriate life in the refugee camps of Nepal. The impetus for this exploratory study stemmed from my personal experience as a cultural orientation trainer to such refugees and awareness of their expectations, attitudes, and dispositions related to learning and life trajectory. This study is interdisciplinary in its approach that takes account of the complex interplay of language learning and integration. Using an ethnographic methodology as an approach to investigation, this study sought to examine three social spaces of refugees: the family and ethnic community, the host society and the migrant English classroom. The attention was focussed on the resources and constraints the refugees encountered in each of the social spaces. Moreover, various social, contextual, cultural factors, and pre-migration influences embedded in these spaces were explored for their impact on learning and integration. This study was important mainly for three reasons. Through critical examination of the role of refugees’ family and ethnic community networks, it aimed to provide insights into to what extent the resources embedded in these networks can be significant to refugees and also contribute to the existing literature of social capital (Putnam, 2000). Drawing on the investigation of how cultural issues, pre-migration experiences and perceptions of teaching impact on classroom language learning, this study sought to offer insights into how the English language should be taught to the adult students from refugee backgrounds. Moreover, this study sought to extend the scope of the existing refugee integration literature by investigating the integration as a process of ongoing negotiation between ethnocultural retention and host society participation, and how various social, cultural, contextual factors, and pre-migration experiences influenced the way integration is structured in everyday practice. This study employed an ethnographic approach as a methodological framework, involving observations, interviews, and a reflective journal study as the main tools for data collection. The field work was carried out in a regional area of the State of Tasmania. The observations were conducted in the migrant English classrooms, in a multi-ethnic Australian church and in the refugee community; and then the retrospective interviews were carried out with the Bhutanese refugees, their teachers and other service providers. The data were analyzed using ethnographic macro and micro level analysis techniques (Duff, 2002). The findings generated from observation data were supported and triangulated, where possible, by the use of data derived from interviews. This study was informed mainly by the interpretive paradigm. Given how extensive and messy the literature on migrant language learning and integration is, this study utilized a wide range of relevant theories to analyze and interpret the findings derived from the ethnographic fieldwork. One important contribution of this study is the finding that the social capital derived from refugees’ family and ethnic community networks not only enables, but it also inhibits integration. This bonding social capital can function as a coping resource for refugees against the effects of culture shock, language shock, and racism, and can facilitate access to a range of instrumental support and information necessary for successful transition to the host society. However, this study also suggests that an extreme level of embeddedness within the cultural and social frames of ethnic space has the potential to jeopardize individual mobility, host society language learning and sustainable integration. This study shows that the cultural dispositions the adult refugee students bring to the classroom provide the primary basis for the way they approach their English learning, and thus influence their agency and identity as learners. The findings also suggest that the students are likely to engage in the desired learning tasks if their perceptions of teaching quality cohere with the actual teaching they are exposed to. Teachers are therefore suggested to adopt a hybridity of teaching approaches and methods in ways that bridge the gap between their own and their students’ perceptions and expectations. The implications drawn from the empirical results additionally suggest that if the aim of the migrant English program is to facilitate the integration of refugees into their multicultural society, then the pedagogy it embodied should incorporate a hybridity of simulation scenarios (native, non-native and coethnic), enabling them to critically examine the impact of different types of identity they portray and negotiate their identities according to social constraints. This study suggests that in order to understand refugee integration more fully, it is not sufficient to account only for the pre-determined set of objective measures (such as employment and educational outcomes) without considering the way in which integration is actualized in everyday experience. For refugees in this study, what it means to be integrated into the Australian society was complex, ambivalent and context dependent. It was an ongoing process of contestation and negotiation between different values, identities and practices embedded in ethnic and mainstream Australia community. Based on my empirical study, I suggest that the everyday practices of refugee integration resembles with Bhabha’s (1990) notion of “Third Space” and incorporates the hybridity of cultural identifications and experiences

A Condensation-Ordering Mechanism in Nanoparticle-Catalyzed Peptide Aggregation

Nanoparticles introduced in living cells are capable of strongly promoting the aggregation of peptides and proteins. We use here molecular dynamics simulations to characterise in detail the process by which nanoparticle surfaces catalyse the self- assembly of peptides into fibrillar structures. The simulation of a system of hundreds of peptides over the millisecond timescale enables us to show that the mechanism of aggregation involves a first phase in which small structurally disordered oligomers assemble onto the nanoparticle and a second phase in which they evolve into highly ordered beta-sheets as their size increases

Multi-parallel qPCR provides increased sensitivity and diagnostic breadth for gastrointestinal parasites of humans: field-based inferences on the impact of mass deworming

BACKGROUND: Although chronic morbidity in humans from soil transmitted helminth (STH) infections can be reduced by anthelmintic treatment, inconsistent diagnostic tools make it difficult to reliably measure the impact of deworming programs and often miss light helminth infections. METHODS: Cryopreserved stool samples from 796 people (aged 2-81 years) in four villages in Bungoma County, western Kenya, were assessed using multi-parallel qPCR for 8 parasites and compared to point-of-contact assessments of the same stools by the 2-stool 2-slide Kato-Katz (KK) method. All subjects were treated with albendazole and all Ascaris lumbricoides expelled post-treatment were collected. Three months later, samples from 633 of these people were re-assessed by both qPCR and KK, re-treated with albendazole and the expelled worms collected. RESULTS: Baseline prevalence by qPCR (n = 796) was 17 % for A. lumbricoides, 18 % for Necator americanus, 41 % for Giardia lamblia and 15% for Entamoeba histolytica. The prevalence was <1% for Trichuris trichiura, Ancylostoma duodenale, Strongyloides stercoralis and Cryptosporidium parvum. The sensitivity of qPCR was 98% for A. lumbricoides and N. americanus, whereas KK sensitivity was 70% and 32%, respectively. Furthermore, qPCR detected infections with T. trichiura and S. stercoralis that were missed by KK, and infections with G. lamblia and E. histolytica that cannot be detected by KK. Infection intensities measured by qPCR and by KK were correlated for A. lumbricoides (r = 0.83, p < 0.0001) and N. americanus (r = 0.55, p < 0.0001). The number of A. lumbricoides worms expelled was correlated (p < 0.0001) with both the KK (r = 0.63) and qPCR intensity measurements (r = 0.60). CONCLUSIONS: KK may be an inadequate tool for stool-based surveillance in areas where hookworm or Strongyloides are common or where intensity of helminth infection is low after repeated rounds of chemotherapy. Because deworming programs need to distinguish between populations where parasitic infection is controlled and those where further treatment is required, multi-parallel qPCR (or similar high throughput molecular diagnostics) may provide new and important diagnostic information

Recent advances in electronic structure theory and their influence on the accuracy of ab initio potential energy surfaces

Recent advances in electronic structure theory and the availability of high speed vector processors have substantially increased the accuracy of ab initio potential energy surfaces. The recently developed atomic natural orbital approach for basis set contraction has reduced both the basis set incompleteness and superposition errors in molecular calculations. Furthermore, full CI calculations can often be used to calibrate a CASSCF/MRCI approach that quantitatively accounts for the valence correlation energy. These computational advances also provide a vehicle for systematically improving the calculations and for estimating the residual error in the calculations. Calculations on selected diatomic and triatomic systems will be used to illustrate the accuracy that currently can be achieved for molecular systems. In particular, the F+H2 yields HF+H potential energy hypersurface is used to illustrate the impact of these computational advances on the calculation of potential energy surfaces

The propensity to adopt evidence-based practice among physical therapists

<p>Abstract</p> <p>Background</p> <p>Many authors, as well as the American Physical Therapy Association, advocate that physical therapists adopt practice patterns based on research evidence, known as evidence-based practice (EBP). At the same time, physical therapists should be capable of integrating EBP within the day-to-day practice of physical therapy. The purpose of this study was to determine the extent to which personal characteristics and the characteristics of the social system in the workplace influence the propensity of physical therapists to adopt EBP.</p> <p>Methods</p> <p>The study used a 69 item mailed self-completion questionnaire. The questionnaire had four major sections. The first three sections were each drawn from a different theoretical framework and from different authors' work. The instrument was developed to capture the propensity of physical therapists to adopt EBP, characteristics of the social system in the workplace of physical therapists, personal characteristics of physical therapists, and selected demographic variables of physical therapists. The eligible population consisted of 3,897 physical therapists licensed by the state of Georgia in the United States of America. A random sample of 1320 potential participants was drawn.</p> <p>Results</p> <p>939 questionnaires were returned for a response rate of 73%. 831 of the participants' questionnaires were useable and became the basis for the study. There was a moderate association between desire for learning (<it>r </it>= .36, <it>r</it>²= .13), highest degree held (<it>r </it>= .29, <it>r</it>²= .08), practicality (<it>r </it>= .27, <it>r</it>²= .07) and nonconformity (<it>r </it>= .24, <it>r</it>²= .06) and the propensity to adopt EBP. A negative correlation was found between age, years licensed and percentage of time in direct patient care. The findings demonstrated that the best three variables for predicting the propensity to adopt EBP in physical therapy were: desire for learning, highest degree held, and practicality.</p> <p>Conclusion</p> <p>The study confirms there is no single factor to facilitate research evidence into day-to-day practice. Multiple practice change strategies will be needed to facilitate change in practice.</p