15,898 research outputs found

    Evolution: Fangtastic Venoms Underpin Parasitic Mimicry

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    Venomous teeth are rare in fishes, which typically utilise spines for defence. A new study reveals the evolutionary origins of fangs and venom in the Nemophini blennies and shows that, in contrast to snakes and lizards, the fangs pre-date the venom

    In vivo functional and myeloarchitectonic mapping of human primary auditory areas

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    In contrast to vision, where retinotopic mapping alone can define areal borders, primary auditory areas such as A1 are best delineated by combining in vivo tonotopic mapping with postmortem cyto- or myeloarchitectonics from the same individual. We combined high-resolution (800 ÎŒm) quantitative T(1) mapping with phase-encoded tonotopic methods to map primary auditory areas (A1 and R) within the "auditory core" of human volunteers. We first quantitatively characterize the highly myelinated auditory core in terms of shape, area, cortical depth profile, and position, with our data showing considerable correspondence to postmortem myeloarchitectonic studies, both in cross-participant averages and in individuals. The core region contains two "mirror-image" tonotopic maps oriented along the same axis as observed in macaque and owl monkey. We suggest that these two maps within the core are the human analogs of primate auditory areas A1 and R. The core occupies a much smaller portion of tonotopically organized cortex on the superior temporal plane and gyrus than is generally supposed. The multimodal approach to defining the auditory core will facilitate investigations of structure-function relationships, comparative neuroanatomical studies, and promises new biomarkers for diagnosis and clinical studies

    A common garden design reveals population-specific variability in potential impacts of hybridisation between populations of farmed and wild Atlantic salmon, Salmo salar L

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    Released individuals can have negative impacts on native populations through various mechanisms; including competition, disease transfer and introduction of maladapted gene-complexes. Previous studies indicate that the level of farmed Atlantic salmon introgression in native populations is population-specific. However few studies have explored the potential role of population diversity or river characteristics, such as temperature, on the consequences of hybridisation. We compared freshwater growth of multiple families derived from two farmed, five wild, and two F1 hybrid salmon populations at three contrasting temperatures (7°C, 12°C, and 16°C) in a common garden experiment. As expected, farmed salmon outgrew wild salmon at all temperatures, with hybrids displaying intermediate growth. However, differences in growth were population-specific and some wild populations performed better than others relative to the hybrid and farmed populations at certain temperatures. Therefore, the competitive balance between farmed and wild salmon may depend both on the thermal profile of the river and the genetic characteristics of the respective farmed and wild strains. While limited to F1 hybridisation, the present study shows the merits in adopting a more complex spatially resolved approach to risk management of local populations

    Preparing the foundations for video-based, practice-placement support: establishing the role from a students’ perspective

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    Currently, many placement-based health programme students within the UK are supported through face-to-face visits from university staff. Whilst cited in literature as being of value, the face-to-face nature of this contact is not supported. Alternatives including video-based communications methods offer the potential for cost effective, environmentally responsible support. However, in order to establish the fitness for purpose of alternative approaches, the content and purpose of current support needs to be understood. This project aimed to investigate student perceptions of the ideal content and purpose of clinical support visits, and alternatives to the current face-to-face approach. Fifty-six Physiotherapy undergraduate students responded to questionnaires with a further nine participating in a follow-up focus group. Participants emphasised the value of the visit in guiding learning, ensuring progression and resolving arising issues, and highlighted concerns over alternative approaches. Focus group participants discussed the importance of personal and professional confidence in directing requirements for support, and went on to propose a menu of options for methods of communication.Whilst limited in some applications, video technologies may be one of the options. Overall, however, this project supports the need for consideration of individualised learning journeys within curriculum planning

    The tripartite efficacy framework in client–therapist rehabilitation interactions: implications for relationship quality and client engagement

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    Purpose: Within supervised rehabilitation programs, Lent and Lopez (2002) proposed that clients and therapists develop a “tripartite” network of efficacy beliefs, comprising their confidence in their own ability, their confidence in the other person’s ability, and their estimation of the other person’s confidence in them. To date, researchers have yet to explore the potential relational outcomes associated with this model in rehabilitation contexts. Method: In Study 1, we recruited 170 exercise clients (M age = 63.73, SD = 6.46) who were enrolled in a one-to-one aerobic exercise program with a therapist as a result of a lower-limb musculoskeletal disorder. Clients reported their tripartite efficacy beliefs and perceptions about the quality of their relationship with their therapist, and respective therapists rated each client’s engagement in his or her exercise program. In Study 2, we recruited 68 separate exercise clients (M age = 65.93 SD = 5.80) along with their therapists (n = 68, M age = 31.89, SD = 4.79) from the same program, to examine whether individuals’ efficacy perceptions were related to their own and/or the other person’s relationship quality perceptions.Results: In Study 1, each of the tripartite efficacy constructs displayed positive direct effects with respect to clients’ relationship quality appraisals, as well as indirect effects in relation to program engagement. Actor partner interdependence modeling in Study 2 demonstrated that clients and therapists reported more adaptive relationship perceptions when they themselves held strong tripartite efficacy beliefs (i.e., actor effects), and that clients viewed their relationship in a more positive light when their therapist was highly confident in the client’s ability (i.e., partner effect). Conclusion: These findings underscore the potential utility of the tripartite efficacy framework in relation to motivational and relational processes within supervised exercise programs

    Millimeter and Submillimeter Survey of the R Corona Australis Region

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    Using a combination of data from the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO), the Arizona Radio Observatory Kitt Peak 12m telescope and the Arizona Radio Observatory 10m Heinrich Hertz Telescope, we have studied the most active part of the R CrA molecular cloud in multiple transitions of Carbon Monoxide, HCO+^+ and 870\micron continuum emission. Since R CrA is nearby (130 pc), we are able to obtain physical spatial resolution as high as 0.01pc over an area of 0.16 pc2^2, with velocity resolution finer than 1 km/s. Mass estimates of the protostar driving the mm-wave emission derived from HCO+^+, dust continuum emission and kinematic techniques point to a young, deeply embedded protostar of ∌\sim0.5-0.75 M⊙_\odot, with a gaseous envelope of similar mass. A molecular outflow is driven by this source that also contains at least 0.8 M⊙_\odot of molecular gas with ∌\sim0.5 L⊙_\odot of mechanical luminosity. HCO+^+ lines show the kinematic signature of infall motions as well as bulk rotation. The source is most likely a Class 0 protostellar object not yet visible at near-IR wavelengths. With the combination of spatial and spectral resolution in our data set, we are able to disentangle the effects of infall, rotation and outflow towards this young object.Comment: 29 pages, 9 figures. Accepted for publication in the Astrophysical Journa

    Experimental harvesting of fish populations drives genetically based shifts in body size and maturation

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    Size-selective harvesting in commercial fisheries can induce rapid changes in biological traits. While experimental and wild harvested populations often exhibit clear shifts in body size and maturation associated with fishing pressure, the relative contributions of genetic and environmental factors to these shifts remain uncertain and have been much debated. To date, observations of so-called fisheries-induced evolution (FIE) have been based solely on phenotypic measures, such as size data. Genetic data are hitherto lacking. Here, we quantify genetic versus environmental change in response to size-selective harvesting for small and large body size in guppies (Poecilia reticulata) across three generations of selection. We document for the first time significant changes at individual genetic loci, some of which have previously been associated with body size. In contrast, variation at neutral microsatellite markers was unaffected by selection, providing direct genetic evidence for rapid evolution induced by size-selective harvesting. These findings demonstrate FIE in an experimental system, with major implications for the sustainability of harvested populations, as well as impacts on size-structured communities and ecosystem processes. These findings highlight the need for scientists and managers to reconsider the capacity of harvested stocks to adapt to, and recover from, harvesting and predation. © 2013 The Ecological Society of America

    Migration of Interplanetary Dust

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    We numerically investigate the migration of dust particles with initial orbits close to those of the numbered asteroids, observed trans-Neptunian objects, and Comet Encke. The fraction of silicate asteroidal particles that collided with the Earth during their lifetime varied from 1.1% for 100 micron particles to 0.008% for 1 micron particles. Almost all asteroidal particles with diameter d>4 microns collided with the Sun. The peaks in the migrating asteroidal dust particles' semi-major axis distribution at the n:(n+1) resonances with Earth and Venus and the gaps associated with the 1:1 resonances with these planets are more pronounced for larger particles. The probability of collisions of cometary particles with the Earth is smaller than for asteroidal particles, and this difference is greater for larger particles.Comment: Annals of the New York Academy of Sciences, 15 pages, 8 Figures, submitte

    Pattern of Reaction Diffusion Front in Laminar Flows

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    Autocatalytic reaction between reacted and unreacted species may propagate as solitary waves, namely at a constant front velocity and with a stationary concentration profile, resulting from a balance between molecular diffusion and chemical reaction. The effect of advective flow on the autocatalytic reaction between iodate and arsenous acid in cylindrical tubes and Hele-Shaw cells is analyzed experimentally and numerically using lattice BGK simulations. We do observe the existence of solitary waves with concentration profiles exhibiting a cusp and we delineate the eikonal and mixing regimes recently predicted.Comment: 4 pages, 3 figures. This paper report on experiments and simulations in different geometries which test the theory of Boyd Edwards on flow advection of chemical reaction front which just appears in PRL (PRL Vol 89,104501, sept2002

    Jellyfish on the menu: mtDNA assay reveals scyphozoan predation in the Irish Sea

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    Localized outbreaks of jellyfish, known as blooms, cause a variety of adverse ecological and economic effects. However, fundamental aspects of their ecology remain unknown. Notably, there is scant information on the role jellyfish occupy in food webs: in many ecosystems, few or no predators are known. To identify jellyfish consumers in the Irish Sea, we conducted a molecular gut content assessment of 50 potential predators using cnidarian-specific mtDNA primers and sequencing. We show that jellyfish predation may be more common than previously acknowledged: uncovering many previously unknown jellyfish predators. A substantial proportion of herring and whiting were found to have consumed jellyfish. Rare ingestion was also detected in a variety of other species. Given the phenology of jellyfish in the region, we suggest that the predation was probably targeting juvenile stages of the jellyfish life cycle
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