1,345 research outputs found

    Predictive Behavior of a Computational Foot/Ankle Model through Artificial Neural Networks

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    Computational models are useful tools to study the biomechanics of human joints. Their predictive performance is heavily dependent on bony anatomy and soft tissue properties. Imaging data provides anatomical requirements while approximate tissue properties are implemented from literature data, when available. We sought to improve the predictive capability of a computational foot/ankle model by optimizing its ligament stiffness inputs using feedforward and radial basis function neural networks. While the former demonstrated better performance than the latter per mean square error, both networks provided reasonable stiffness predictions for implementation into the computational model

    Is alexithymia characterised by impaired interoception?:Further evidence, the importance of control variables, and the problems with the Heartbeat Counting Task

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    Interoception, the perception of one’s internal state, is commonly quantified using the heartbeat counting task (HCT) – which is thought to be a measure of cardiac interoceptive sensitivity (accuracy). Interoceptive sensitivity has been associated with a number of clinical traits and aspects of higher order cognition, including emotion processing and decision-making. It has been proposed that alexithymia (difficulties identifying and describing one’s own emotions) is associated with impaired interoceptive sensitivity, but new research questions this association. Problematically, much evidence attesting to the absence of this association has been conducted using the HCT, a measure affected by various physiological and psychological factors. Here, we present novel data (N = 287) examining the relationship between alexithymia and HCT performance, controlling for a number of potential confounds. Inclusion of these control measures reveals the predicted negative relationship between alexithymia and HCT performance. Results are discussed with regard to difficulties quantifying interoceptive sensitivity using the HCT

    Migration pattern of Gambel’s White-crowned Sparrow along the Pacific Flyway

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    White-crowned Sparrow (Zonotrichia leucophrys) populations of western North America exhibit dramatic differences in life history strategies including migration behavior. However, individual migration strategies and population-level migratory patterns remain largely unknown for this species. Here, we focused on the long-distance migratory subspecies, Gambel’s White-crowned Sparrow (Zonotrichia leucophrys gambelii). We used ringing, tracking and stable hydrogen isotope (δ2H) analysis of individuals migrating along the Pacific Flyway to assess individual phenology and routes as well as the pattern of connectivity between breeding and non-breeding sites. Results from all three methods, consisting of 79 ring recoveries, four light level geolocator tracks and 388 feather δ2H values, indicate low degrees of migratory connectivity. The isotope data provide evidence for leapfrog migration with the more southerly populations traveling greater distances to the breeding grounds than more centrally wintering individuals. Location estimates of four annual journeys revealed individually consistent migration strategies with relatively short flight bouts separated by two to three and two to six stopover sites during spring and autumn migration, respectively. However, combined results from all methods indicate high variability in migration distance among individuals. These findings confirm the phenotypic flexibility observed within this species and highlight the potential of White-crowned Sparrows for further investigations of evolutionary adaptations to ongoing changes in the environment

    The dynamics of animal social networks: Analytical, conceptual, and theoretical advances

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    Social network analysis provides a broad and complex perspective on animal sociality that is widely applicable to almost any species. Recent applications demonstrate the utility of network analysis for advancing our understanding of the dynamics, selection pressures, development, and evolution of complex social systems. However, most studies of animal social networks rely primarily on a descriptive approach. To propel the field of animal social networks beyond exploratory analyses and to facilitate the integration of quantitative methods that allow for the testing of ecologically and evolutionarily relevant hypotheses, we review methodological and conceptual advances in network science, which are underutilized in studies of animal sociality. First, we highlight how the use of statistical model- ing and triadic motifs analysis can advance our understanding of the processes that structure networks. Second, we discuss how the consideration of temporal changes and spatial constraints can shed light on the dynamics of social networks. Third, we consider how the study of variation at multiple scales can potentially transform our understanding of the structure and function of animal networks. We direct readers to analytical tools that facilitate the adoption of these new concepts and methods. Our goal is to provide behavioral ecologists with a toolbox of current methods that can stimulate novel insights into the ecological influences and evolutionary pressures structuring networks and advance our understanding of the proximate and ultimate processes that drive animal sociality

    The dynamics of animal social networks: Analytical, conceptual, and theoretical advances

    Get PDF
    Social network analysis provides a broad and complex perspective on animal sociality that is widely applicable to almost any species. Recent applications demonstrate the utility of network analysis for advancing our understanding of the dynamics, selection pressures, development, and evolution of complex social systems. However, most studies of animal social networks rely primarily on a descriptive approach. To propel the field of animal social networks beyond exploratory analyses and to facilitate the integration of quantitative methods that allow for the testing of ecologically and evolutionarily relevant hypotheses, we review methodological and conceptual advances in network science, which are underutilized in studies of animal sociality. First, we highlight how the use of statistical model- ing and triadic motifs analysis can advance our understanding of the processes that structure networks. Second, we discuss how the consideration of temporal changes and spatial constraints can shed light on the dynamics of social networks. Third, we consider how the study of variation at multiple scales can potentially transform our understanding of the structure and function of animal networks. We direct readers to analytical tools that facilitate the adoption of these new concepts and methods. Our goal is to provide behavioral ecologists with a toolbox of current methods that can stimulate novel insights into the ecological influences and evolutionary pressures structuring networks and advance our understanding of the proximate and ultimate processes that drive animal sociality

    Furthering the language hypothesis of alexithymia: An integrated review and meta-analysis

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    Alexithymia, including the inability to identify and express one’s own feelings, is a subclinical condition responsible for some of the socioemotional symptoms seen across a range of psychiatric conditions. The language hypothesis of alexithymia posits a language-mediated disruption in the development of discrete emotion concepts from ambiguous affective states, exacerbating the risk of developing alexithymia in language-impaired individuals. To provide a critical evaluation, a systematic review and meta-analysis of 29 empirical studies of language functioning in alexithymia was performed. A modest association was found between alexithymia and multi-domain language deficits (r = -0.14), including structural language, pragmatics, and propensity to use emotional language. A more theoretically-relevant subsample analysis comparing alexithymia levels in language-impaired and typical individuals revealed larger effects, but a limited number of studies adopted this approach. A synthesis of 11 emotional granularity studies also found an association between alexithymia and reduced emotional granularity (r = -0.10). Language impairments seem to increase the risk of alexithymia. Heterogeneous samples and methods suggest the need for studies with improved alexithymia assessment

    AMI-LA radio continuum observations of Spitzer c2d small clouds and cores: Perseus region

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    We present deep radio continuum observations of the cores identified as deeply embedded young stellar objects in the Perseus molecular cloud by the Spitzer c2d programme at a wavelength of 1.8 cm with the Arcminute Microkelvin Imager Large Array (AMI-LA). We detect 72% of Class 0 objects from this sample and 31% of Class I objects. No starless cores are detected. We use the flux densities measured from these data to improve constraints on the correlations between radio luminosity and bolometric luminosity, infrared luminosity and, where measured, outflow force. We discuss the differing behaviour of these objects as a function of protostellar class and investigate the differences in radio emission as a function of core mass. Two of four possible very low luminosity objects (VeLLOs) are detected at 1.8 cm.Comment: 18 pages, 9 figures, accepted MNRA

    Implementation and Conduct of Therapeutic Hypothermia for Perinatal Asphyxial Encephalopathy in the UK – Analysis of National Data

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    BACKGROUND: Delay in implementing new treatments into clinical practice results in considerable health and economic opportunity costs. Data from the UK TOBY Cooling Register provides the opportunity to examine how one new effective therapy for newborn infants suspected of suffering asphyxial encephalopathy--therapeutic hypothermia- was implemented in the UK. METHODOLOGY/PRINCIPAL FINDINGS: We analysed returned data forms from inception of the Register in December 2006 to the end of July 2011. Data forms were received for 1384 (67%) of the 2069 infants registered. The monthly rate of notifications increased from median {IQR} 18 {15-31} to 33 {30-39} after the announcement of the results of the recent TOBY trial, and to 50 {36-55} after their publication. This rate further increased to 70 {64-83} following official endorsement of the therapy, and is now close to the expected numbers of eligible infants. Cooling was started at 3.3 {1.5-5.5} hours after birth and the time taken to achieve the target 33-34 °C rectal temperature was 1 {0-3} hours. The rectal temperature was in the target range in 83% of measurements. From 2006 to 2011 there was evidence of extension of treatment to slightly less severely affected infants. 278 of 1362 (20%) infants died at 2.9 {1.4-4.1} days of age. The rates of death fell slightly over the period of the Register and, at two years of age cerebral palsy was diagnosed in 22% of infants; half of these were spastic bilateral. Factors independently associated with adverse outcome were clinical seizures prior to cooling (p<0.001) and severely abnormal amplitude integrated EEG (p<0.001). CONCLUSIONS/SIGNIFICANCE: Therapeutic hypothermia was implemented appropriately within the UK, with significant benefit to patients and the health economy. This may be due in part to participation by neonatal units in clinical trials, the establishment of the national Register, and its endorsement by advisory bodies
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