A crystal plasticity study of the micromechanics of interfaces in TiAl

Submicron resolution deformation mapping techniques implemented into both micro and macro mechanical testing have recently provided measurements of the deformation of titanium aluminide at the microstructural scale. Experimental observations indicate that damage in such alloy strongly depends on the way shear localization associated with slip bands or twins is accommodated at the interface between colonies. Here, crystal plasticity finite element analysis has been carried out to simulate the relevant micromechanics. It is shown that it is possible to capture the deformation patterns observed at colony boundaries, therefore providing trustworthy predictions of the associated stress field. Different conditions are explored for which a given imposed deformation can be achieved with minimum stress concentration. The implications for microstructure engineering aimed to delay the nucleation of damage in such alloy are discussed

Krill biomass estimation : sampling and measurement variability

FB is funded by an EPSRC studentship (grant code: EP/R513337/1).Krill are the subject of growing commercial fisheries and therefore fisheries management is necessary to ensure long-term sustainability. Krill catch limits, set by Commission for the Conservation of Antarctic Marine Living Resources, are based on absolute krill biomass, estimated from acoustic-trawl surveys. In this work, we develop a method for determining an error budget for acoustic-trawl surveys of krill which includes sampling and measurement variability. We use our error budget method to examine the sensitivity of biomass estimates to parameters in acoustic target strength (TS) models, length frequency distribution and length to wetmass relationships derived from net data. We determined that the average coefficient of variation (CV) of estimated biomass was 17.7% and the average CV due from scaling acoustic observations to biomass density was 5.3%. We found that a large proportion of the variability of biomass estimates is due to the krill orientation distribution, a parameter in the TS model. Orientation distributions with narrow standard deviations were found to emphasise the results of nulls in the TS to length relationship, which has to potential to lead to biologically implausible results.Publisher PDFPeer reviewe

Ariel - Volume 2 Number 3

Editors Delvyn C. Case, Jr. Paul M. Fernhoff News Editors Richard Bonanno Daniel B. Gould Robin A. Edwards Lay-Out Editor Carol Dolinskas Sports Editor James J. Nocon Contributing Editors Michael J. Blecker Lin Sey Edwards Jack Guralnik W. Cherry Light Features Editor Steven A. Ager Donald A. Bergman Stephen P. Flynn Business Manager Nick Greg

Recent trends in UK insects that inhabit early successional stages of ecosystems

Improved recording of less popular groups, combined with new statistical approaches that compensate for datasets that were hitherto too patchy for quantitative analysis, now make it possible to compare recent trends in the status of UK invertebrates other than butterflies. Using BRC datasets, we analysed changes in status between 1992 and 2012 for those invertebrates whose young stages exploit early seral stages within woodland, lowland heath and semi-natural grassland ecosystems, a habitat type that had declined during the 3 decades previous to 1990 alongside a disproportionally high number of Red Data Book species that were dependent on it. Two clear patterns emerged from a meta-analysis involving 299 classifiable species belonging to ten invertebrate taxa: (i) during the past 2 decades, most early seral species that are living near their northern climatic limits in the UK have increased relative to the more widespread members of these guilds whose distributions were not governed by a need for a warm micro-climate; and (ii) independent of climatic constraints, species that are restricted to the early stages of woodland regeneration have fared considerably less well than those breeding in the early seral stages of grasslands or, especially, heathland. The first trend is consistent with predicted benefits for northern edge-of-range species as a result of climate warming in recent decades. The second is consistent with our new assessment of the availability of early successional stages in these three ecosystems since c. 1990. Whereas the proportion and continuity of early seral patches has greatly increased within most semi-natural grasslands and lowland heaths, thanks respectively to agri-environmental schemes and conservation management, the representation of fresh clearings has continued to dwindle within UK woodlands, whose floors are increasingly shaded and ill-suited for this important guild of invertebrates

The depression in visual impairment trial (DEPVIT): trial design and protocol

<b>Background</b> The prevalence of depression in people with a visual disability is high but screening for depression and referral for treatment is not yet an integral part of visual rehabilitation service provision. One reason for this may be that there is no good evidence about the effectiveness of treatments in this patient group. This study is the first to evaluate the effect of depression treatments on people with a visual impairment and co morbid depression.<p></p> <b>Methods/design</b> The study is an exploratory, multicentre, individually randomised waiting list controlled trial. Participants will be randomised to receive Problem Solving Therapy (PST), a ‘referral to the GP’ requesting treatment according to the NICE’s ‘stepped care’ recommendations or the waiting list arm of the trial. The primary outcome measure is change (from randomisation) in depressive symptoms as measured by the Beck’s Depression Inventory (BDI-II) at 6 months. Secondary outcomes include change in depressive symptoms at 3 months, change in visual function as measured with the near vision subscale of the VFQ-48 and 7 item NEI-VFQ at 3 and 6 months, change in generic health related quality of life (EQ5D), the costs associated with PST, estimates of incremental cost effectiveness, and recruitment rate estimation.<p></p> <b>Discussion</b> Depression is prevalent in people with disabling visual impairment. This exploratory study will establish depression screening and referral for treatment in visual rehabilitation clinics in the UK. It will be the first to explore the efficacy of PST and the effectiveness of NICE’s ‘stepped care’ approach to the treatment of depression in people with a visual impairment.<p></p&gt

Sintering of calcium phosphates with a femtosecond pulsed laser for hard tissue engineering

The authors acknowledge support from the sponsors of this work; the EPSRC LUMIN (EP/K020234/1) and EU-Marie-Curie-IAPP LUSTRE (324538) projects.Direct laser sintering on hard tissues is likely to open new pathways for personalised medicine. To minimise irradiation damage of the surrounding soft tissues, lasers operating at wavelengths that are ‘safe’ for the tissues and biomaterials with improved optical properties are required. In this work laser sintering is demonstrated with the use of an ultrafast, femtosecond (100 fs) pulsed laser operating at a wavelength of 1045 nm and two existing calcium phosphate minerals (brushite and hydroxyapatite) which have been improved after doping with iron (10 mol%). Femtosecond laser irradiation caused transformation of the Fe3+-doped brushite and Fe3+-doped HAp samples into β-calcium pyrophosphate and calcium-iron-phosphate, respectively, with simultaneous evidence for microstructural sintering and densification. After estimating the temperature profile at the surface of the samples we suggest that soft tissues over 500 μm from the irradiated zone would be safe from thermal damage. This novel laser processing provides a means to control the phase constitution and the morphology of the finished surfaces. The porous structure of β-pyrophosphate might be suitable for applications in bone regeneration by supporting osteogenic cell activity while, the densified Fe3+-rich calcium-iron-phosphate may be promising for applications like dental enamel restoration.PostprintPeer reviewe

Impact of the earthworm Lumbricus terrestris (L.) on As, Cu, Pb and Zn mobility and speciation in contaminated soils

To assess the risks that contaminated soils pose to the environment properly a greater understanding of how soil biota influence the mobility of metal(loid)s in soils is required. Lumbricus terrestris L. were incubated in three soils contaminated with As, Cu, Pb and Zn. The concentration and speciation of metal(loid)s in pore waters and the mobility and partitioning in casts were compared with earthworm-free soil. Generally the concentrations of water extractable metal(loid)s in earthworm casts were greater than in earthworm-free soil. The impact of the earthworms on concentration and speciation in pore waters was soil and metal specific and could be explained either by earthworm induced changes in soil pH or soluble organic carbon. The mobilisation of metal(loid)s in the environment by earthworm activity may allow for leaching or uptake into biota

Depressive symptoms in people with vision impairment: a cross-sectional study to identify who is most at risk

Objective: To identify the risk factors for significant depressive symptoms in people with visual impairment in England and Wales to provide information on who is most at risk and to whom support services could be targeted in future. Design: A cross-sectional study using baseline data from a pragmatic randomised controlled trial. Setting and participants: 990 participants aged 18 or over attending 1 of 14 low-vision rehabilitation primary care optometry-based clinics in South Wales or two hospital clinics in London. Outcome measure: A score of ≥6 on the Geriatric Depression Scale-15 was classed as clinically significant depressive symptoms. Results: In a multivariable logistic regression model, significant depressive symptoms were associated with age (adjusted OR (AOR)=0.82, 95% CI: 0.66 to 0.90, p<0.001), ethnicity (AOR non-white compared with white=1.72, 95% CI: 1.05 to 2.81, p=0.031), total number of eye conditions (AOR for two vs one condition=0.98, 95% CI: 0.67 to 1.43; three or more vs one condition=0.34, 95% CI: 0.15 to 0.75, p=0.026), self-reported health (AOR for excellent vs poor=0.01, 95% CI: 0.00 to 0.12; very good vs poor=0.06, 95% CI: 0.03 to 0.13; good vs poor=0.14, 95% CI: 0.08 to 0.24; fair vs poor=0.28, 95% CI: 0.18 to 0.46, p<0.001) and self-reported visual functioning (AOR=1.45, 95% CI: 1.31 to 1.61, p<0.001). Conclusion: Younger age, a non-white ethnicity, fewer eye conditions and poorer self-reported health and visual function are risk factors for significant depressive symptoms in this population. Trial registration number: ISRCTN46824140; Pre-results

Local adaptation does not constrain the expression of behaviour in translocated wild crickets

Behaviour has the potential to retard evolutionary adaptation by equipping animals with the capacity to radically change their interactions with the environment without evolving. Despite this potential for plasticity, laboratory studies frequently identify among-population differences in responses to identical stimuli, suggesting that genetic adaption often reduces behavioural flexibility. However, laboratory environments are typically far removed from nature, so their relevance to the variation we might expect to see in the wild (either among environments or as a result of changes in climate) is unclear. This is a particularly acute issue in relation to behaviour because behaving in an optimal fashion requires animals to receive and process complex sensory information which may be disrupted by laboratory conditions. We translocated newly adult male field crickets, Gryllus campestris, from five high-altitude and five low-altitude populations into a single low-altitude meadow from which we had removed all naturally present males. By tagging every individual and employing a network of 140 video cameras we were able to record comprehensive behavioural information from early adulthood until death. This allowed us to directly compare the behaviour of individuals from populations known to be genetically divergent and adapted to either high or low altitudes. We found very limited evidence for an effect on behaviour of the altitudinal environment in which crickets had evolved and developed, despite the large scale of our study (>20 000h of observations of 128 males). Our findings suggests that when provided with all the environmental cues present in their natural environment, local adaptation does not lead to substantial constraints on behaviour. This supports the hypothesis that the potential flexibility of behaviour may tend to reduce selection for local adaptation