1,429 research outputs found

    Assessment of Neuropsychological Trajectories in Longitudinal Population-Based Studies of Children

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    This paper provides a strategy for the assessment of brain function in longitudinal cohort studies of children. The proposed strategy invokes both domain-specific and omnibus intelligence test approaches. In order to minimise testing burden and practice effects, the cohort is divided into four groups with one-quarter tested at 6-monthly intervals in the 0–2-year age range (at ages 6 months, 1.0, 1.5 and 2.0 years) and at annual intervals from ages 3–20 (one-quarter of the children at age 3, another at age 4, etc). This strategy allows investigation of cognitive development and of the relationship between environmental influences and development at each age. It also allows introduction of new domains of function when age-appropriate. As far as possible, tests are used that will provide a rich source of both longitudinal and cross-sectional data. The testing strategy allows the introduction of novel tests and new domains as well as piloting of tests when the test burden is relatively light. In addition to the recommended tests for each age and domain, alternative tests are described. Assessment methodology and knowledge about child cognitive development will change over the next 20 years, and strategies are suggested for altering the proposed test schedule as appropriate

    Noncanonical Quantization of Gravity. I. Foundations of Affine Quantum Gravity

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    The nature of the classical canonical phase-space variables for gravity suggests that the associated quantum field operators should obey affine commutation relations rather than canonical commutation relations. Prior to the introduction of constraints, a primary kinematical representation is derived in the form of a reproducing kernel and its associated reproducing kernel Hilbert space. Constraints are introduced following the projection operator method which involves no gauge fixing, no complicated moduli space, nor any auxiliary fields. The result, which is only qualitatively sketched in the present paper, involves another reproducing kernel with which inner products are defined for the physical Hilbert space and which is obtained through a reduction of the original reproducing kernel. Several of the steps involved in this general analysis are illustrated by means of analogous steps applied to one-dimensional quantum mechanical models. These toy models help in motivating and understanding the analysis in the case of gravity.Comment: minor changes, LaTeX, 37 pages, no figure

    Further Evidence for Seed Size Variation in the Genus Zostera: Exploratory Studies with Z. japonica and Z. asiatica

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    Recent studies found seed size variation within the seagrass Zostera marina, one of nine species in the genus Zostera. The objectives of this study were to determine if variation also exists in the seeds of two other species Zostera japonica and Zostera asiatica within this genus. Results indicate that: (1) length and weight varied between two populations (one indigenous population from Akkeshi-Ko, Japan, and one exotic population from Willapa Bay, Washington, USA) of the small-bodied intertidal seagrass species Z. japonica, and (2) seed-size classes were discernable. Preliminary investigations were also initiated with a Japanese population of Z. asiatica, a large-bodied subtidal seagrass species. Z. japonica seeds from the exotic population were significantly (P \u3c 0.00 1) longer and heavier when compared to those from the indigenous population, a finding which may help explain both the process of the earlier introduction and the recent expansion of this exotic in the northeastern Pacific. Also, preliminary results indicate that Z. asiatica seeds are heavier than both those of Z. marina and Z. japonica, which suggests that larger seeds may be associated with large-bodied plants in this genus, an observation that should direct future seed ecology studies within the genus. These findings demonstrate that, similar to the study of terrestrial angiosperms, investigations designed to describe the comparative ecology of marine seed-bearing plants should include an evaluation of seed size

    A note on the cylindrical collapse of counter-rotating dust

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    We find analytical solutions describing the collapse of an infinitely long cylindrical shell of counter-rotating dust. We show that--for the classes of solutions discussed herein--from regular initial data a curvature singularity inevitably develops, and no apparent horizons form, thus in accord with the spirit of the hoop conjecture.Comment: 8 pages, LaTeX, ijmpd macros (included), 1 eps figure; accepted for publication in Int. J. Mod. Phys.

    The Unruh-deWitt Detector and the Vacuum in the General Boundary formalism

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    We discuss how to formulate a condition for choosing the vacuum state of a quantum scalar field on a timelike hyperplane in the general boundary formulation (GBF) using the coupling to an Unruh-DeWitt detector. We explicitly study the response of an Unruh-DeWitt detector for evanescent modes which occur naturally in quantum field theory in the presence of the equivalent of a dielectric boundary. We find that the physically correct vacuum state has to depend on the physical situation outside of the boundaries of the spacetime region considered. Thus it cannot be determined by general principles pertaining only to a subset of spacetime.Comment: Version as published in CQ

    DBCollab: Automated feedback for face-to-face group database design

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    © 2017 Asia-Pacific Society for Computers in Education. All rights reserved. Developing effective teamwork and collaboration skills is regarded as a key graduate attribute for employability. As a result, higher education institutions are striving to help students foster these skills through authentic learning scenarios. Although face-to-face (f2f) group tasks are common in most classrooms, it is challenging to collect evidence about the group processes. As a result, to date, it is difficult to assess group tasks in ways other than through teachers' direct observations and students' self-reports, or by measuring the quality of their final product. However, there are other critical aspects of group-work that students need to receive feedback on, for example, interaction dynamics or the collaboration processes. This paper explores the potential of using interactive surfaces and sensors to track key indicators of group-work, to provide automated feedback about epistemic and social aspects. We conducted a pilot study in an authentic classroom, in the context of database design. The contributions of this paper are: 1) the operationalisation of the DBCollab tool as a means for supporting group database design and collecting multimodal traces of the activity using interactive surfaces and sensors; and 2) empirical evidence that points at the potential of presenting these traces to group members in order to provoke immediate and post-hoc productive reflection about their activity

    Multimodal collaborative workgroup dataset and challenges

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    © 2017, CEUR-WS. All rights reserved. This work presents a multimodal dataset of 17 workgroup sessions in a collaborative learning activity. Workgroups were conformed of two or three students using a tabletop application in a co-located space. The dataset includes time-synchronized audio, video and tabletop system's logs. Some challenges were identified during the collection of the data, such as audio participation identification, and user traces identification. Future work should explore how to overcome the aforementioned difficulties

    Cell Type Impacts Accessibility of mRNA to Silencing by RNA Interference

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    RNA interference (RNAi) is a potent mechanism that silences mRNA and protein expression in all cells and tissue types. RNAi is known to exert many of its functional effects in the cytoplasm, and thus, the cellular localization of target mRNA may impact observed potency. Here, we demonstrate that cell identity has a profound impact on accessibility of apolipoprotein E (ApoE) mRNA to RNAi. We show that, whereas both neuronal and glial cell lines express detectable ApoE mRNA, in neuronal cells, ApoE mRNA is not targetable by RNAi. Screening of a panel of thirty-five chemically modified small interfering RNAs (siRNAs) did not produce a single hit in a neuronal cell line, whereas up to fifteen compounds showed strong efficacy in glial cells. Further investigation of the cellular localization of ApoE mRNA demonstrates that ApoE mRNA is partially spliced and preferentially localized to the nucleus ( approximately 80%) in neuronal cells, whereas more than 90% of ApoE mRNA is cytoplasmic in glial cells. Such an inconsistency in intracellular localization and splicing might provide an explanation for functional differences in RNAi compounds. Thus, cellular origin might have an impact on accessibility of mRNA to RNAi and should be taken into account during the screening process
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