Quasi-static, impact and energy absorption of internally nested tubes subjected to lateral loading

This is an accepted manuscript of an article published by Elsevier in Thin-walled Structures on 20/10/2015, available online: https://doi.org/10.1016/j.tws.2015.10.001 The accepted version of the publication may differ from the final published version.© 2015 Published by Elsevier Ltd. This paper presents the responses of nested tube systems under quasi-static and dynamic lateral loading. Nested systems in the form of short internally stacked tubes were proposed as energy absorbing structures for applications that have limited crush zones. Three configurations of nested tube systems were experimentally analysed in this paper. The crush behaviour and energy absorbing responses of these systems under various loading conditions were presented and discussed. It was found that the quasi-static and dynamic responses of the nested systems were comparable under an experimental velocity of v=4.5 m/sec. This is due to insignificant strain rate and inertia effects of the nested systems under the applied velocity. The performance indicators, which describe the effectiveness of energy absorbing systems, were calculated to compare the various nested systems and the best system was identified. Furthermore, the effects of geometrical and loading parameters on the responses of the best nested tube system were explored via performing parametric analysis. The parametric study was performed using validated finite element models. The outcome of this parametric study was full detailed design guidelines for such nested tube energy absorbing structures.Published versio

Von Bezold assimilation effect reverses in stereoscopic conditions

Lightness contrast and lightness assimilation are opposite phenomena: in contrast, grey targets appear darker when bordering bright surfaces (inducers) rather than dark ones; in assimilation, the opposite occurs. The question is: which visual process favours the occurrence of one phenomenon over the other? Researchers provided three answers to this question. The first asserts that both phenomena are caused by peripheral processes; the second attributes their occurrence to central processes; and the third claims that contrast involves central processes, whilst assimilation involves peripheral ones. To test these hypotheses, an experiment on an IT system equipped with goggles for stereo vision was run. Observers were asked to evaluate the lightness of a grey target, and two variables were systematically manipulated: (i) the apparent distance of the inducers; and (ii) brightness of the inducers. The retinal stimulation was kept constant throughout, so that the peripheral processes remained the same. The results show that the lightness of the target depends on both variables. As the retinal stimulation was kept constant, we conclude that central mechanisms are involved in both lightness contrast and lightness assimilation

Application of Magnetic Nanoparticles in Pharmaceutical Sciences

# The Author(s) 2010. This article is published with open access at Springerlink.com KEY WORDS magnetic beads. magnetic bioseparation. magnetic nanoparticle

Ranking and rating bicycle helmet safety performance in oblique impacts using eight different brain injury models

Bicycle helmets are shown to offer protection against head injuries. Rating methods and test standards are used to evaluate different helmet designs and safety performance. Both strain-based injury criteria obtained from finite element brain injury models and metrics derived from global kinematic responses can be used to evaluate helmet safety performance. Little is known about how different injury models or injury metrics would rank and rate different helmets. The objective of this study was to determine how eight brain models and eight metrics based on global kinematics rank and rate a large number of bicycle helmets (n=17) subjected to oblique impacts. The results showed that the ranking and rating are influenced by the choice of model and metric. Kendall’s tau varied between 0.50 and 0.95 when the ranking was based on maximum principal strain from brain models. One specific helmet was rated as 2-star when using one brain model but as 4-star by another model. This could cause confusion for consumers rather than inform them of the relative safety performance of a helmet. Therefore, we suggest that the biomechanics community should create a norm or recommendation for future ranking and rating methods

Modeling SAGE tag formation and its effects on data interpretation within a Bayesian framework

<p>Abstract</p> <p>Background</p> <p>Serial Analysis of Gene Expression (SAGE) is a high-throughput method for inferring mRNA expression levels from the experimentally generated sequence based tags. Standard analyses of SAGE data, however, ignore the fact that the probability of generating an observable tag varies across genes and between experiments. As a consequence, these analyses result in biased estimators and posterior probability intervals for gene expression levels in the transcriptome.</p> <p>Results</p> <p>Using the yeast <it>Saccharomyces cerevisiae </it>as an example, we introduce a new Bayesian method of data analysis which is based on a model of SAGE tag formation. Our approach incorporates the variation in the probability of tag formation into the interpretation of SAGE data and allows us to derive exact joint and approximate marginal posterior distributions for the mRNA frequency of genes detectable using SAGE. Our analysis of these distributions indicates that the frequency of a gene in the tag pool is influenced by its mRNA frequency, the cleavage efficiency of the anchoring enzyme (AE), and the number of informative and uninformative AE cleavage sites within its mRNA.</p> <p>Conclusion</p> <p>With a mechanistic, model based approach for SAGE data analysis, we find that inter-genic variation in SAGE tag formation is large. However, this variation can be estimated and, importantly, accounted for using the methods we develop here. As a result, SAGE based estimates of mRNA frequencies can be adjusted to remove the bias introduced by the SAGE tag formation process.</p

Avian cholera, a threat to the viability of an Arctic seabird colony?

© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 7 (2012): e29659, doi:10.1371/journal.pone.0029659.Evidence that infectious diseases cause wildlife population extirpation or extinction remains anecdotal and it is unclear whether the impacts of a pathogen at the individual level can scale up to population level so drastically. Here, we quantify the response of a Common eider colony to emerging epidemics of avian cholera, one of the most important infectious diseases affecting wild waterfowl. We show that avian cholera has the potential to drive colony extinction, even over a very short period. Extinction depends on disease severity (the impact of the disease on adult female survival) and disease frequency (the number of annual epidemics per decade). In case of epidemics of high severity (i.e., causing >30% mortality of breeding females), more than one outbreak per decade will be unsustainable for the colony and will likely lead to extinction within the next century; more than four outbreaks per decade will drive extinction to within 20 years. Such severity and frequency of avian cholera are already observed, and avian cholera might thus represent a significant threat to viability of breeding populations. However, this will depend on the mechanisms underlying avian cholera transmission, maintenance, and spread, which are currently only poorly known.The study was supported by the Canadian Wildlife Service-Environment Canada (http://www.ec.gc.ca/), Nunavut Wildlife Management Board (http:// www.nwmb.com/), Greenland Institute of Natural Resources (http://www.natur.gl/), Polar Continental Shelf Project (http://polar.nrcan.gc.ca/), Fonds Que´be´cois de la Recherche sur la Nature et les Technologies (http://www.fqrnt.gouv.qc.ca/), Canadian Network of Centres of Excellence ArcticNet (http://www.arcticnet.ulaval. ca/), Natural Sciences and Engineering Research Council of Canada (http://www.nserc-crsng.gc.ca/), and the Department of Indian Affairs and Northern Canada (http://www.ainc-inac.gc.ca/)

The association between intimate partner violence, alcohol and depression in family practice

Background: Depressive symptoms, intimate partner violence and hazardous drinking are common among patients attending general practice. Despite the high prevalence of these three problems; the relationship between them remains relatively unexplored. Methods: This paper explores the association between depressive symptoms, ever being afraid of a partner and hazardous drinking using cross-sectional screening data from 7667 randomly selected patients from a large primary care cohort study of 30 metropolitan and rural general practices in Victoria, Australia. The screening postal survey included the Center for Epidemiological Studies Depression Scale, the Fast Alcohol Screening Test and a screening question from the Composite Abuse Scale on ever being afraid of any intimate partner. Results: 23.9% met criteria for depressive symptoms. A higher proportion of females than males (20.8% vs. 7.6%) reported ever being afraid of a partner during their lifetime (OR 3.2, 95%CI 2.5 to 4.0) and a lower proportion of females (12%) than males (25%) were hazardous drinkers (OR 0.4; 95%CI 0.4 to 0.5); and a higher proportion of females than males (20.8% vs. 7.6%) reported ever being afraid of a partner during their lifetime (OR 3.2, 95%CI 2.5 to 4.0). Men and women who had ever been afraid of a partner or who were hazardous drinkers had on average higher depressive symptom scores than those who had never been afraid or who were not hazardous drinkers. There was a stronger association between depressive symptoms and ever been afraid of a partner compared to hazardous drinking for both males (ever afraid of partner; Diff 6.87; 95% CI 5.42, 8.33; p < 0.001 vs. hazardous drinking in last year; Diff 1.07, 95% CI 0.21, 1.94; p = 0.015) and females (ever afraid of partner; Diff 5.26; 95% CI 4.55, 5.97; p < 0.001 vs. hazardous drinking in last year; Diff 2.23, 95% CI 1.35, 3.11; p < 0.001), even after adjusting for age group, income, employment status, marital status, living alone and education level. Conclusions: Strategies to assist primary care doctors to recognise and manage intimate partner violence and hazardous drinking in patients with depression may lead to better outcomes from management of depression in primary care

Transcriptome dynamics and molecular cross-talk between bovine oocyte and its companion cumulus cells

<p>Abstract</p> <p>Background</p> <p>The bi-directional communication between the oocyte and its companion cumulus cells (CCs) is crucial for development and functions of both cell types. Transcripts that are exclusively expressed either in oocytes or CCs and molecular mechanisms affected due to removal of the communication axis between the two cell types is not investigated at a larger scale. The main objectives of this study were: 1. To identify transcripts exclusively expressed either in oocyte or CCs and 2. To identify those which are differentially expressed when the oocyte is cultured with or without its companion CCs and vice versa.</p> <p>Results</p> <p>We analyzed transcriptome profile of different oocyte and CC samples using Affymetrix GeneChip Bovine Genome array containing 23000 transcripts. Out of 13162 genes detected in germinal vesicle (GV) oocytes and their companion CCs, 1516 and 2727 are exclusively expressed in oocytes and CCs, respectively, while 8919 are expressed in both. Similarly, of 13602 genes detected in metaphase II (MII) oocytes and CCs, 1423 and 3100 are exclusively expressed in oocytes and CCs, respectively, while 9079 are expressed in both. A total of 265 transcripts are differentially expressed between oocytes cultured with (OO + CCs) and without (OO - CCs) CCs, of which 217 and 48 are over expressed in the former and the later groups, respectively. Similarly, 566 transcripts are differentially expressed when CCs mature with (CCs + OO) or without (CCs - OO) their enclosed oocytes. Of these, 320 and 246 are over expressed in CCs + OO and CCs - OO, respectively.</p> <p>While oocyte specific transcripts include those involved in transcription (<it>IRF6, POU5F1, MYF5, MED18</it>), translation (<it>EIF2AK1, EIF4ENIF1</it>) and CCs specific ones include those involved in carbohydrate metabolism (<it>HYAL1, PFKL, PYGL, MPI</it>), protein metabolic processes (<it>IHH, APOA1, PLOD1</it>), steroid biosynthetic process (<it>APOA1, CYP11A1, HSD3B1, HSD3B7</it>). Similarly, while transcripts over expressed in OO + CCs are involved in carbohydrate metabolism (<it>ACO1, 2</it>), molecular transport (<it>GAPDH, GFPT1</it>) and nucleic acid metabolism (<it>CBS, NOS2</it>), those over expressed in CCs + OO are involved in cellular growth and proliferation (<it>FOS, GADD45A</it>), cell cycle (<it>HAS2, VEGFA</it>), cellular development (<it>AMD1, AURKA, DPP4</it>) and gene expression (<it>FOSB, TGFB2</it>).</p> <p>Conclusion</p> <p>In conclusion, this study has generated large scale gene expression data from different oocyte and CCs samples that would provide insights into gene functions and interactions within and across different pathways that are involved in the maturation of bovine oocytes. Moreover, the presence or absence of oocyte and CC factors during bovine oocyte maturation can have a profound effect on transcript abundance of each cell types, thereby showing the prevailing molecular cross-talk between oocytes and their corresponding CCs.</p