4,385 research outputs found

    Association between the squat lobster Gastroptychus formosus and cold-water corals in the North Atlantic

    Get PDF
    Although there are no previous descriptions of the habits of chirostylids in the North Atlantic, it is likely that species in the genera Uroptychus, Eumunida and Gastroptychus have close ecological ties with deep-sea corals since they have all been recorded in trawl samples containing corals from āˆ¼200m depth. We analysed in situ distribution of Gastroptychus formosus and potential hosts using a ROV at a range of north-eastern Atlantic sites and found that this species forms a close association with deep-sea corals that resembles the chirostylid-anthozoan associations reported in shallow Indo-Pacific waters. We update the known distribution for G. formosus, confirming that it is an amphiatlantic species that occurs along the Mid-Atlantic Ridge at least as far south as the Azores and along continental margins from the Canary Islands to Scotland at depths of 600-1700m. The adults have very specific habitat preferences, being only found on gorgonian and antipatharian corals with a strong preference for Leiopathes sp. as a host. This highly restricted habitat preference is likely to render chirostylids vulnerable to the impacts of demersal fishing both directly, as by-catch, and indirectly through habitat loss. Ā© 2010 Marine Biological Association of the United Kingdom

    Autonomous Robotic System using Non-Destructive Evaluation methods for Bridge Deck Inspection

    Full text link
    Bridge condition assessment is important to maintain the quality of highway roads for public transport. Bridge deterioration with time is inevitable due to aging material, environmental wear and in some cases, inadequate maintenance. Non-destructive evaluation (NDE) methods are preferred for condition assessment for bridges, concrete buildings, and other civil structures. Some examples of NDE methods are ground penetrating radar (GPR), acoustic emission, and electrical resistivity (ER). NDE methods provide the ability to inspect a structure without causing any damage to the structure in the process. In addition, NDE methods typically cost less than other methods, since they do not require inspection sites to be evacuated prior to inspection, which greatly reduces the cost of safety related issues during the inspection process. In this paper, an autonomous robotic system equipped with three different NDE sensors is presented. The system employs GPR, ER, and a camera for data collection. The system is capable of performing real-time, cost-effective bridge deck inspection, and is comprised of a mechanical robot design and machine learning and pattern recognition methods for automated steel rebar picking to provide realtime condition maps of the corrosive deck environments

    Everyday functioning of people with Parkinsonā€™s disease and impairments in executive function: a qualitative investigation

    Get PDF
    ArticleThis is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this record.Purpose: Executive function is the key area of cognitive impairment in Parkinsonā€™s disease. This study investigated how cognitive difficulties impact on everyday life of people with Parkinsonā€™s disease and their carers, and whether they explicitly mention executive-type difficulties. Methods: Semistructured interviews with 11 people with Parkinsonā€™s disease and six carers were analyzed thematically. People with Parkinsonā€™s disease performed within the normal range on cognitive screening tests, but all had abnormal scores on tests of executive function. Results: Despite relatively mild executive deficits and no global cognitive impairment, participants described executive-type difficulties as well as a range of problems in other cognitive domains, such as memory, processing speed and apathy. Cognitive difficulties had a far-reaching impact on everyday life and their significance depended on personal circumstances, such as the level of responsibilities of the person with Parkinsonā€™s disease and the extent of available support. Conclusions: By presenting subjective accounts of living with Parkinsonā€™s disease and cognitive difficulties, this study improves our understanding of how the observed level of cognitive impairment translates into everyday functioning. The study results have implications for recognizing cognitive difficulties and for planning support for people with Parkinsonā€™s disease and their families, and can help identify ways of promoting effective self-management. ā€¢Implications for rehabilitation ā€¢Treatment of Parkinsonā€™s disease tends to focus on the movement disorder, meaning that cognitive difficulties and their impact can be overlooked. ā€¢Participants in this study had only relatively mild executive deficits but described a range of cognitive problems, including executive-type difficulties. ā€¢Cognitive difficulties have an emotional impact and can cause a range of challenges in everyday life, adding to the burden of physical symptoms of Parkinsonā€™s disease. ā€¢Results of this study provide insights into how executive functions impairments translate into everyday difficulties in Parkinsonā€™s disease and have implications for planning support for people with Parkinsonā€™s disease and their families

    Stress-driven instability in growing multilayer films

    Full text link
    We investigate the stress-driven morphological instability of epitaxially growing multilayer films, which are coherent and dislocation-free. We construct a direct elastic analysis, from which we determine the elastic state of the system recursively in terms of that of the old states of the buried layers. In turn, we use the result for the elastic state to derive the morphological evolution equation of surface profile to first order of perturbations, with the solution explicitly expressed by the growth conditions and material parameters of all the deposited layers. We apply these results to two kinds of multilayer structures. One is the alternating tensile/compressive multilayer structure, for which we determine the effective stability properties, including the effect of varying surface mobility in different layers, its interplay with the global misfit of the multilayer film, and the influence of asymmetric structure of compressive and tensile layers on the system stability. The nature of the asymmetry properties found in stability diagrams is in agreement with experimental observations. The other multilayer structure that we study is one composed of stacked strained/spacer layers. We also calculate the kinetic critical thickness for the onset of morphological instability and obtain its reduction and saturation as number of deposited layers increases, which is consistent with recent experimental results. Compared to the single-layer film growth, the behavior of kinetic critical thickness shows deviations for upper strained layers.Comment: 27 pages, 11 figures; Phys. Rev. B, in pres

    Deconvolving the pre-Himalayan Indian margin ā€“ tales of crustal growth and destruction

    Get PDF
    The metamorphic core of the Himalaya is composed of Indian cratonic rocks with two distinct crustal affinities that are defined by radiogenic isotopic geochemistry and detrital zircon age spectra. One is derived predominantly from the Paleoproterozoic and Archean rocks of the Indian cratonic interior and is either represented as metamorphosed sedimentary rocks of the Lesser Himalayan Sequence (LHS) or as slices of the distal cratonic margin. The other is the Greater Himalayan Sequence (GHS) whose provenance is less clear and has an enigmatic affinity. Here we present new detrital zircon Hf analyses from LHS and GHS samples spanning over 1000 kilometers along the orogen that respectively show a striking similarity in age spectra and Hf isotope ratios. Within the GHS, the zircon age populations at 2800ā€“2500 Ma, 1800 Ma, 1000 Ma and 500 Ma can be ascribed to various Gondwanan source regions; however, a pervasive and dominant Tonian age population (āˆ¼860ā€“800 Ma) with a variably enriched radiogenic Hf isotope signature (ĪµHf = 10 to -20) has not been identified from Gondwana or peripheral accreted terranes. We suggest this detrital zircon age population was derived from a crustal province that was subsequently removed by tectonic erosion. Substantial geologic evidence exists from previous studies across the Himalaya supporting the Cambro-Ordovician Kurgiakh Orogeny. We propose the tectonic removal of Tonian lithosphere occurred prior to or during this Cambro-Ordovician episode of orogenesis in a similar scenario as is seen in the modern Andean and Indonesian orogenies, wherein tectonic processes have removed significant portions of the continental lithosphere in a relatively short amount of time. This model described herein of the pre-Himalayan northern margin of Greater India highlights the paucity of the geologic record associated with the growth of continental crust. Although the continental crust is the archive of Earth history, it is vital to recognize the ways in which preservation bias and destruction of continental crust informs geologic models

    Morphological and molecular assessment of Lithophyllum okamurae with the description of L. neo-okamurae sp. nov. (Corallinales, Rhodophyta)

    Get PDF
    Lithophyllum okamurae has been widely reported in the Pacific Ocean with identification based on morpho-anatomical observations. Two infraspecific taxa, L. okamurae f. okamurae and f. angulare, described from Japan, have been recorded in the temperate region of Japan. We assessed branched Lithophyllum samples morphologically referable to L. okamurae using morpho-anatomical data and DNA sequences (psbA, rbcL and partial LSU rDNA) obtained from herbarium specimens, including type material, as well as recently field-collected material in Japan. The molecular analyses showed that these ā€˜L. okamuraeā€™ samples contained two species: L. okamurae and a cryptic new species which we describe as L. neo-okamurae sp. nov. Because the holotype of L. okamurae f. angulare was conspecific with original material cited in the protologue of L. okamurae, it is a heterotypic synonym of L. okamurae f. okamurae. Lithophyllum okamurae and L. neo-okamurae were morphologically similar in having warty, lumpy and fruticose thalli and in often forming rhodoliths. Lithophyllum okamurae can be morpho-anatomically distinguished from L. neo-okamurae by the thallus with tapering or plate-like protuberances (knobby protuberances in the latter) and by having smaller tetrasporangial conceptacle chambers (167ā€“314 Ī¼m; 248ā€“380 Ī¼m in L. neo-okamurae). Our LSU rDNA sequence data from L. okamurae f. angulare (=L. okamurae f. okamurae) was identical to that of the type of L. margaritae, which has nomenclatural priority over L. okamurae. However, considering that psbA and rbcL sequences of L. margaritae type material could not be generated in the present study, we refrain, for the moment, from proposing the taxonomic synonymy between these two taxa until the status of L. margaritae and its synonyms from the type locality (Gulf of California) are clarified.This research was mainly supported by Japan Society for the Promotion of Science (JSPS KAKENHI Grant Number 26850123, 17K07908) to AK
    • ā€¦
    corecore