24 research outputs found

    The application of optical coherence tomography to image subsurface tissue structure of Antarctic krill Euphausia superba

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    Many small open ocean animals, such as Antarctic krill, are an important part of marine ecosystems. To discover what will happen to animals such as krill in a changing ocean, experiments are run in aquaria where conditions can be controlled to simulate water characteristics predicted to occur in the future. The response of individual animals to changing water conditions can be hard to observe, and with current observation techniques it is very difficult to follow the progress of an individual animal through its life. Optical coherence tomography (OCT) is an optical imaging technique that allows images at high resolution to be obtained from depths up to a few millimeters inside biological specimens. It is compatible with in vivo imaging and can be used repeatedly on the same specimens. In this work, we show how OCT may be applied to post mortem krill samples and how important physiological data such as shell thickness and estimates of organ volume can be obtained. Using OCT we find an average value for the thickness of krill exoskeleton to be (30±4) µm along a 1 cm length of the animal body. We also show that the technique may be used to provide detailed imagery of the internal structure of a pleopod joint and provide an estimate for the heart volume of (0.73±0.03) mm3

    Two-photon ablation with 1278 nm laser radiation

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    We report on precise two- photon ablation with 110 fs laser pulses at 1278 nm, emitted from a Cr: forsterite laser. Selective two- photon ablation of Muntjac deer chromosomes is demonstrated. The two- photon absorption at 639 nm was enhanced by using Methylene blue dye as a photosensitizer. This stain has a strong absorption in the region around 650 nm but 100% transmission around 1300 nm, allowing increased specificity: material that has absorbed the dye is ablated but undyed material is left unaffected. The low group velocity dispersion in glass at 1278 nm led to negligible pulse broadening in the focusing objective where the 100 fs pulses stretched to 110 fs. This contrasts to the 100 fs pulses at 780 nm that were measured to stretch to 300 fs under the same conditions.</p

    Data from: The application of optical coherence tomography to image subsurface tissue structure of Antarctic krill Euphausia superba

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    Many small open ocean animals, such as Antarctic krill, are an important part of marine ecosystems. To discover what will happen to animals such as krill in a changing ocean, experiments are run in aquaria where conditions can be controlled to simulate water characteristics predicted to occur in the future. The response of individual animals to changing water conditions can be hard to observe, and with current observation techniques it is very difficult to follow the progress of an individual animal through its life. Optical coherence tomography (OCT) is an optical imaging technique that allows images at high resolution to be obtained from depths up to a few millimeters inside biological specimens. It is compatible with in vivo imaging and can be used repeatedly on the same specimens. In this work, we show how OCT may be applied to post mortem krill samples and how important physiological data such as shell thickness and estimates of organ volume can be obtained. Using OCT we find an average value for the thickness of krill exoskeleton to be (30&plusmn;4) &micro;m along a 1 cm length of the animal body. We also show that the technique may be used to provide detailed imagery of the internal structure of a pleopod joint and provide an estimate for the heart volume of (0.73&plusmn;0.03) mm3. </span

    Orientation effect on mechanical properties of commercially pure titanium at room temperature

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    The effect of sample orientation on the mechanical properties of commercially pure (CP) titanium plate with a transverse split basal texture was investigated at room temperature (RT) using plane strain compression (PSC). A large variation in flow stress of up to (EBSD) and calculating Schmid factors for all important slip and twinning modes. Importantly, the Schmid factors were calculated for all orientations in Euler space because there are significant variations over all orientations for the PSC stress state, unlike uniaxial compression or tension. The Schmid factor analysis and twin data for the wide variety of orientations tested enabled the conclusion to be drawn reliably that higher flow stresses were primarily due to an unfavourable orientation for prism- slip. A greater proportion of to twinning was also a major factor in the higher flow stresses. Increased strain hardening was observed in the sample orientation that showed a dramatic texture change to a more difficult orientation for further deformation as a result of dominant twinning. This indicated that reorientation hardening was the responsible mechanism

    The impact of HENRY on parenting and family lifestyle: a national service evaluation of a preschool obesity prevention programme

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    Objectives: One in five children in England are overweight/obese at school entry. Tackling obesity is therefore a priority. Right from the Start with HENRY is a widely commissioned programme delivered by trained facilitators to small groups of parents over eight, weekly sessions. It is designed to provide parents of infants and preschool children with the skills, knowledge and confidence required for a healthier family lifestyle. The aim of this work was to investigate programme impact using data collected routinely for quality control purposes. Study design: Analysis of routinely collected pre-post data from programmes delivered in the UK January 2012 – February 2014. Methods: Data were analysed from 144 programmes, including questionnaires relating to parenting, family eating behaviours, dietary intake, and physical activity/screen time. Results: Over 24 months, 1100 parents attended programmes running in 86 locations. 788 (72%) completed >5 sessions of whom 624 (79%) provided baseline and completion questionnaires. Parents reported increases in healthiness of family lifestyle, parenting attributes, and emotional wellbeing following attendance (all p<.001). Both parents and children were reported to have increased their daily fruit/vegetable consumption, and reduced their consumption of high fat/sugar foods (both p<.001). There were also positive changes in eating behaviours, physical activity (p<.001) and children’s screen time (p<.001). Conclusions: Significant changes were reported in all domains similar to those reported in a previous, smaller study in locations selected for experience and quality. The HENRY approach appears to have a beneficial impact even when delivered at scale in non-selected locations. Such changes, if maintained, may serve to protect against later obesity

    Old fossils–young species: evolutionary history of an endemic gastropod assemblage in Lake Malawi

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    Studies on environmental changes provide important insights into modes of speciation, into the (adaptive) reoccupation of ecological niches and into species turnover. Against this background, we here examine the history of the gastropod genus Lanistes in the African Rift Lake Malawi, guided by four general evolutionary scenarios, and compare it with patterns reported from other endemic Malawian rift taxa. Based on an integrated approach using a mitochondrial DNA phylogeny and a trait-specific molecular clock in combination with insights from the fossil record and palaeoenvironmental data, we demonstrate that the accumulation of extant molecular diversity in the endemic group did not start before approximately 600 000 years ago from a single lineage. Fossils of the genus from the Malawi Rift, however, are over one million years older. We argue that severe drops in the lake level of Lake Malawi in the Pleistocene offer a potential explanation for this pattern. Our results also challenge previously established phylogenetic relationships within the genus by revealing parallel evolution and providing evidence that the endemic Lanistes species are not restricted to the lake proper but are present throughout the Malawi Rift
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