1,832 research outputs found

    Forecasting Sensorimotor Adaptability from Baseline Inter-Trial Correlations

    Get PDF
    One of the greatest challenges for sensorimotor adaptation to the spaceflight environment is the large variability in symptoms, and corresponding functional impairments, from one crewmember to the next. This renders preflight training and countermeasure development difficult, as a "one-size-fits-all" approach is inappropriate. Therefore, it would be highly advantageous to know ahead of time which crewmembers might have more difficulty adjusting to the novel g-levels inherent to spaceflight. This information could guide individually customized countermeasures, which would enable more efficient use of crew time and provide better outcomes. The principal aim of this work is to look for baseline performance metrics that relate to locomotor adaptability. We propose a novel hypothesis that considers baseline inter-trial correlations, the trial-to-trial fluctuations ("noise") in motor performance, as a predictor of individual adaptive capabilities

    Automobile Emissions in Mexico City

    Get PDF

    Impaired object tracking in children with chromosome 22q11.2 deletion syndrome

    Get PDF
    Background: Chromosome 22q11.2 Deletion Syndrome (22q11.2DS) occurs in approximately 1:4,000 live births with a complex and variable presentation that includes medical, socioemotional and psychological symptoms with intellectual impairment. Cognitive impairments in spatiotemporal and visuospatial attention have also been reported. However, maintenance of selective attention to dynamic and interacting objects has not been systematically investigated in children with 22q11.2DS. Methods: We used a multiple object tracking task to assay capacity and resolution performance of children with 22q11.2DS aged 7 to 14 years versus age-matched typically developing (TD) peers. Results: Children with 22q11.2DS but not TD children demonstrated impaired performance when task demands increased due to an increase in the number of targets presented, but not from an increase in object speed. Task performance in children with 22q11.2DS was also unrelated to intelligence or measures of attention deficit hyperactivity disorder. Conclusions: These findings suggest that children with 22q11.2DS may be particularly susceptible to dynamic crowding of objects with increasing cognitive demands related to monitoring multiple targets reflecting a reduced acuity in spatiotemporal cognitive representation

    Impaired object tracking in children with chromosome 22q11.2 deletion syndrome

    Get PDF
    Background: Chromosome 22q11.2 Deletion Syndrome (22q11.2DS) occurs in approximately 1:4,000 live births with a complex and variable presentation that includes medical, socioemotional and psychological symptoms with intellectual impairment. Cognitive impairments in spatiotemporal and visuospatial attention have also been reported. However, maintenance of selective attention to dynamic and interacting objects has not been systematically investigated in children with 22q11.2DS. Methods: We used a multiple object tracking task to assay capacity and resolution performance of children with 22q11.2DS aged 7 to 14 years versus age-matched typically developing (TD) peers. Results: Children with 22q11.2DS but not TD children demonstrated impaired performance when task demands increased due to an increase in the number of targets presented, but not from an increase in object speed. Task performance in children with 22q11.2DS was also unrelated to intelligence or measures of attention deficit hyperactivity disorder. Conclusions: These findings suggest that children with 22q11.2DS may be particularly susceptible to dynamic crowding of objects with increasing cognitive demands related to monitoring multiple targets reflecting a reduced acuity in spatiotemporal cognitive representation

    3,000 words in Spanish L2 basic language courses: A reachable goal?

    Get PDF
    While studies on lexical development in English L2 abound, less is known about how learners develop their lexicons in other L2s and how their developmental paths relate to lexical frequency counts. To fill this gap, this longitudinal study tracks the receptive lexical knowledge of students who progress through three semesters of Spanish L2 in a US university. Using an online receptive vocabulary test taken at the end of each semester, this study explores what percentage of the 3,000 most frequent Spanish words (overall and by frequency band) these learners recognized. Factors influencing outcomes such as whether the students had Spanish courses before the university, or whether they spoke Spanish outside of class were also examined. Results are consistent with English L2 research. Moreover, as L2 learners’ proficiency increased, less additional vocabulary was learned. Previous experiences and use of Spanish outside of class positively influenced scores. On average, learners could recognize around 65% of the most frequent 3,000 words by the end of the third semester. These findings have practical implications for designing the vocabulary component of language courses during and after the first three semesters

    A numerical adaptation of SAW identities from the honeycomb to other 2D lattices

    Full text link
    Recently, Duminil-Copin and Smirnov proved a long-standing conjecture by Nienhuis that the connective constant of self-avoiding walks on the honeycomb lattice is 2+2.\sqrt{2+\sqrt{2}}. A key identity used in that proof depends on the existence of a parafermionic observable for self-avoiding walks on the honeycomb lattice. Despite the absence of a corresponding observable for SAW on the square and triangular lattices, we show that in the limit of large lattices, some of the consequences observed on the honeycomb lattice persist on other lattices. This permits the accurate estimation, though not an exact evaluation, of certain critical amplitudes, as well as critical points, for these lattices. For the honeycomb lattice an exact amplitude for loops is proved.Comment: 21 pages, 7 figures. Changes in v2: Improved numerical analysis, giving greater precision. Explanation of why we observe what we do. Extra reference

    Translational Vestibulo-Ocular Reflex and Motion Perception During Interaural Linear Acceleration: Comparison of Different Motion Paradigms

    Get PDF
    The neural mechanisms to resolve ambiguous tilt-translation motion have been hypothesized to be different for motion perception and eye movements. Previous studies have demonstrated differences in ocular and perceptual responses using a variety of motion paradigms, including Off-Vertical Axis Rotation (OVAR), Variable Radius Centrifugation (VRC), translation along a linear track, and tilt about an Earth-horizontal axis. While the linear acceleration across these motion paradigms is presumably equivalent, there are important differences in semicircular canal cues. The purpose of this study was to compare translation motion perception and horizontal slow phase velocity to quantify consistencies, or lack thereof, across four different motion paradigms. Twelve healthy subjects were exposed to sinusoidal interaural linear acceleration between 0.01 and 0.6 Hz at 1.7 m/s/s (equivalent to 10 tilt) using OVAR, VRC, roll tilt, and lateral translation. During each trial, subjects verbally reported the amount of perceived peak-to-peak lateral translation and indicated the direction of motion with a joystick. Binocular eye movements were recorded using video-oculography. In general, the gain of translation perception (ratio of reported linear displacement to equivalent linear stimulus displacement) increased with stimulus frequency, while the phase did not significantly vary. However, translation perception was more pronounced during both VRC and lateral translation involving actual translation, whereas perceptions were less consistent and more variable during OVAR and roll tilt which did not involve actual translation. For each motion paradigm, horizontal eye movements were negligible at low frequencies and showed phase lead relative to the linear stimulus. At higher frequencies, the gain of the eye movements increased and became more inphase with the acceleration stimulus. While these results are consistent with the hypothesis that the neural computational strategies for motion perception and eye movements differ, they also indicate that the specific motion platform employed can have a significant effect on both the amplitude and phase of each

    Education Provision for Indigenous and Minority Heritage Languages Revitalisation: A Study Focusing on Saami and Scottish Gaelic

    Get PDF
    This chapter provides a comparative study of education provision for the Indigenous language of Saami and the minority heritage of Scottish Gaelic. Due to historical factors, both languages are considered endangered according to UNESCO listings. Whilst North Saami and Scottish Gaelic receive government support, which would appear to be providing a reasonably stable position at least within their geographically core areas, assimilation continues resulting in the overall numbers of speakers remaining small. As education is viewed as key to the promotion of both languages, following an introduction to the background historical and societal context of both language contexts, the chapter presents educational practices and challenges in education for comparison over the past forty years. The comparative study highlights that similarities between these two languages exist in language revitalisation efforts to reverse language shift but the forms vary. The chapter concludes with some emerging recommendations for the successful maintenance and revitalisation of minority heritage and Indigenous languages in the twenty-first century despite the continued dominance of surrounding majority languages
    corecore