680 research outputs found

    Is it Time to Move On? Reflections on a Research Agenda for Self-Directed Learning in the 21st Century

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    Self-directed learning has been one of the most studied areas of adult education over the past three decades. Instead of abandoning this line of inquiry, more research is needed that explores the topic from new perspective

    Double bracket dissipation in kinetic theory for particles with anisotropic interactions

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    We derive equations of motion for the dynamics of anisotropic particles directly from the dissipative Vlasov kinetic equations, with the dissipation given by the double bracket approach (Double Bracket Vlasov, or DBV). The moments of the DBV equation lead to a nonlocal form of Darcy's law for the mass density. Next, kinetic equations for particles with anisotropic interaction are considered and also cast into the DBV form. The moment dynamics for these double bracket kinetic equations is expressed as Lie-Darcy continuum equations for densities of mass and orientation. We also show how to obtain a Smoluchowski model from a cold plasma-like moment closure of DBV. Thus, the double bracket kinetic framework serves as a unifying method for deriving different types of dynamics, from density--orientation to Smoluchowski equations. Extensions for more general physical systems are also discussed.Comment: 19 pages; no figures. Submitted to Proc. Roy. Soc.

    Reframing the Meaning of Self-Directed Learning: An Updated Modeltt

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    Over the past several decades, self-directed learning (SDL) has been one of the most active areas of inquiry within adult education and learning. Several studies have identified trends in this body of knowledge (e.g., Brockett, Stockdale, Fogerson, Cox, Canipe, Chuprina, Donaghy, & Chadwell, 2001; Conner, Carter, Dieffenderfer, & Brockett, 2009; Kirk, Shih, Holt, Smeltzer, & Brockett, 2012). Since 1987, an international symposium has been held annually to share the latest thinking about SDL theory, research, and practice. In 2002 the International Journal of Self-Directed Learning also began publication

    Control of trapped-ion quantum states with optical pulses

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    We present new results on the quantum control of systems with infinitely large Hilbert spaces. A control-theoretic analysis of the control of trapped ion quantum states via optical pulses is performed. We demonstrate how resonant bichromatic fields can be applied in two contrasting ways -- one that makes the system completely uncontrollable, and the other that makes the system controllable. In some interesting cases, the Hilbert space of the qubit-harmonic oscillator can be made finite, and the Schr\"{o}dinger equation controllable via bichromatic resonant pulses. Extending this analysis to the quantum states of two ions, a new scheme for producing entangled qubits is discovered.Comment: Submitted to Physical Review Letter

    Beyond The Inquiring Mind: Cyril Houle’s Connection to Self-Directed Learning

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    This paper examines the early development of self-directed learning as an area of study and practice using Cyril Houle as the point of departure. Through a variety of sources, a perspective is offered on how self-directed learning gained a foothold as a viable area of inquiry in adult education

    Is there a Place at the Adult Education Table for Positive Psychology?: Theorizing from the Literature

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    The purpose of this paper is to address the potential relationship that could be established between adult education and positive psychology by understanding the foundation, possible contradictions, and concerns of positive psychology

    Revitalizing the Study of Self-Directed Adult Learning

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    Self-directed learning has been an important research area in adult education for the past three decades, and holds much potential for future scholarship. Three areas for possible future inquiry are examined

    A cautionary note on methods of comparing programmatic efficiency between two or more groups of DMUs in data envelopment analysis

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    In some applications of data envelopment analysis (DEA) there may be doubt as to whether all the DMUs form a single group with a common efficiency distribution. The Mann-Whitney rank statistic has been used to evaluate if two groups of DMUs come from a common efficiency distribution under the assumption of them sharing a common frontier and to test if the two groups have a common frontier. These procedures have subsequently been extended using the Kruskal-Wallis rank statistic to consider more than two groups. This technical note identifies problems with the second of these applications of both the Mann-Whitney and Kruskal-Wallis rank statistics. It also considers possible alternative methods of testing if groups have a common frontier, and the difficulties of disaggregating managerial and programmatic efficiency within a non-parametric framework. © 2007 Springer Science+Business Media, LLC

    The relationship between subchondral bone cysts and cartilage health in the Tibiotalar joint: A finite element analysis

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    Background: Subchondral bone cysts are a common presentation in ankle haemarthropathy. The relationship with ankle joint health has however not previously been investigated. The aim of this study was to assess the influence of subchondral bone cysts of differing shapes, volumes and depths on joint health. Methods: Chronologically sequential Magnetic Resonance imaging scans of four hemophilic ankles with subchondral bone cysts present (N = 18) were used to build patient specific finite element models under two cystic conditions to assess their influence on cartilage contact pressures. Variables such as location, volume and depth were considered individually, to investigate whether certain cystic conditions may be more detrimental to cartilage health. Findings: Significant quantifiable contact redistribution was seen in the presence of subchondral bone cysts and this redistribution reflected the shape and size of the cysts, however, with the presence of cysts in both bones in 10 of the 18 cases a direct relationship to volume could not be correlated. Interpretation: This work demonstrated a redistribution of contact pressures in the presence of subchondral bone cysts. This alteration to loading history could be linked to cartilage degeneration due to the biological response to abnormal loading

    Morphological variation of the hemophilic talus

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    Flattening of the trochlear tali is clinically observed as structural and functional changes advance in patients with hemarthropathy of the ankle. However, the degree of this flattening has not yet been quantified, and distribution of the morphological changes across the talus not yet defined. Chronologically sequential MR images of both a hemophilic patient group (N = 5) and a single scan from a nondiseased, sex-matched, control group (N = 11) were used to take four measurements of the trochlear talus morphology at three locations (medial, central and lateral) along the sagittal plane. Three ratios of interest were defined from these to assess whether the talar dome flattens with disease. The control group MRI measurements were validated against literature data obtained from CT scans or planar X-Rays. The influence of disease on talar morphology was assessed by direct comparison of the hemophilic cases with the control group. The values for all three ratios, in all locations, differed between the control and the hemophilic group. Flattening was indicated in the hemophilic group in the medial and lateral talus, but differences in the central talus were not statistically significant. This work demonstrates that morphological assessment of the talus from MR images is similar to that from CT scans or planar X-Rays. Talar flattening does occur with hemarthropathy, especially at the medial and lateral edges of the joint surface. General flattening of the trochlear talus was confirmed in this small patient sample, however the degree and rate of change is unique to each ankle
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