1,635 research outputs found
Exploration of Sensemaking in the Education of Novices to the Complex Cognitive Work Domain of Air Traffic Control
Many current complex business and industry jobs consist primarily of cognitive work; however, current approaches to training may be inadequate for this type of work (Hoffman, Feltovich, Fiore, Klein, & Ziebell, 2009). To try and improve training and education for cognitive work, Klein and Baxter (2006) have proposed cognitive transformation theory (CTT), a learning theory that claims that sensemaking activities are essential for acquiring expertise that is adaptive and thus well suited for cognitive work domains. In the present research, cognitive task analysis methods were used to identify and assess sensemaking support in the instruction and learning of complex concepts by two experienced air traffic control professors and seven of their students. The goal of this research was to compare instructional strategies used in an academic setting with the predictions of CTT to gain insight into strategies for the application of CTT. Cognitive task analysis methods employed included course observation, artifact examination, and knowledge elicitation sessions with two professors and seven of their students. Knowledge elicitation transcriptions were coded using categories derived from CTT and the data/frame theory of sensemaking (e.g. Klein, Moon, & Hoffman, 2006; Sieck, Klein, Peluso, Smith, & Harris-Thompson, 2007) to assess theoretical and applied implications for learning and instruction in a complex domain. Findings are represented by synthesizing theory driven predictions with grounded training strategies and technologies. In addition, recommendations are advanced for applying CTT to training and educational systems in order to provide sensemaking support during early phases of learning from which expertise may be developed
Fractal Bubble Cosmology: A concordant cosmological model?
The Fractal Bubble model has been proposed as a viable cosmology that does
not require dark energy to account for cosmic acceleration, but rather
attributes its observational signature to the formation of structure. In this
paper it is demonstrated that, in contrast to previous findings, this model is
not a good fit to cosmological supernovae data; there is significant tension in
the best fit parameters obtained from different samples, whereas LCDM is able
to fit all datasets consistently. Furthermore, the concordance between galaxy
clustering scales and data from the cosmic microwave background is not achieved
with the most recent supernova compilations. The validity of the FB formalism
as a sound cosmological model is further challenged as it is shown that
previous studies of this model achieve concordance by requiring a value for the
present day Hubble constant that is derived from supernovae data containing an
arbitrary distance normalisation.Comment: 6 pages, 3 figures, revised version published in MNRAS letter
Imaging the Near Field
In an earlier paper we introduced the concept of the perfect lens which
focuses both near and far electromagnetic fields, hence attaining perfect
resolution. Here we consider refinements of the original prescription designed
to overcome the limitations of imperfect materials. In particular we show that
a multi-layer stack of positive and negative refractive media is less sensitive
to imperfections. It has the novel property of behaving like a fibre-optic
bundle but one that acts on the near field, not just the radiative component.
The effects of retardation are included and minimized by making the slabs
thinner. Absorption then dominates image resolution in the near-field. The
deleterious effects of absorption in the metal are reduced for thinner layers.Comment: RevTeX, (9 pages, 8 figures
Charged Dilaton Black Holes with a Cosmological Constant
The properties of static spherically symmetric black holes, which are either
electrically or magnetically charged, and which are coupled to the dilaton in
the presence of a cosmological constant, are considered. It is shown that such
solutions do not exist if the cosmological constant is positive (in arbitrary
spacetime dimension >= 4). However, asymptotically anti-de Sitter black hole
solutions with a single horizon do exist if the cosmological constant is
negative. These solutions are studied numerically in four dimensions and the
thermodynamic properties of the solutions are derived. The extreme solutions
are found to have zero entropy and infinite temperature for all non-zero values
of the dilaton coupling constant.Comment: 12 pages, epsf, phyzzx, 4 in-text figures incl. (minor typos fixed, 1
reference added
Team Interaction Dynamics during Collaborative Problem Solving
The need for better understanding collaborative problem solving (CPS) is rising in prominence as many organizations are increasingly addressing complex problems requiring the combination of diverse sets of individual expertise to address novel situations. This research draws from theoretical and empirical work that describes the knowledge coordination arising from team communications during CPS and builds from this by incorporating methods to study interaction dynamics. Interaction between team members in such contexts is inherently dynamic and exhibits nonlinear patterns not accounted for by extant research methods. To redress this gap, the present study draws from methods designed to study social and team interaction as a nonlinear dynamical system. CPS was examined by studying knowledge building and interaction processes of 43 dyads working to solve NASA’s Moonbase Alpha simulation. Specifically, frame-differencing, an automated video analysis technique, was used to capture the bodily movements of participants and content coding was applied to the teams’ communications to characterize their CPS processes. A combination of linear and nonlinear analytic and modeling techniques were applied to quantify and predict CPS performance based on the observed interaction dynamics and other individual differences. We hypothesized that teams exhibiting synchronization in their bodily movements and complementarity in their communications would produce better problem solving outcomes. The present research advances theory and empirical knowledge on effective team interaction during CPS and provides practical guidance on methods that can be used to observe and quantify interaction dynamics during CPS in complex work domains
Adult Thyroglossal Duct Carcinoma of Thyroid Epithelial Origin: A Retrospective Observational Study
Thyroglossal duct or cyst carcinoma (TGDCCa) is uncommon. Current treatments follow those of thyroid cancer but controversy exists over the extent of thyroid and lymph node surgery. Our aim was to study the presentation, treatment strategies and clinical outcomes in patients presenting with TGDCCa. Of 637 patients diagnosed with thyroid cancer over 15-years, 4 patients (0.6 %) with TGDCCa were identified. Two patients were diagnosed outside this time period. Details of demographics, presentation, diagnosis, management and outcomes of all 6 patients were reviewed. 5 females and 1 male with a median (range) age of 41 (21–70) years were treated for TGDCCa. Five patients were diagnosed after initial surgery for thyroglossal cyst—cyst excision (n = 2) and Sistrunk’s procedure (n = 3). This was followed by a total thyroidectomy (TT) in 4 of these patients. One patient underwent Sistrunk’s operation, total thyroidectomy and central neck dissection at the first operation. I131 therapy was used in patients who had TT. Three patients had additional tumour foci in the thyroid. However, lymph node recurrence occurred in 2 patients at 6 and 16 months. At a median follow up of 55 months, all 6 patients were disease free. All patients had papillary TGDCCa and did well with conventional treatment as for thyroid cancer. The extent of treatment required is debatable as half the patients had additional thyroid foci and no patient had clinically or radiologically involved lymph nodes at presentation. A systematic review of published cases will help summarise the existing knowledge base
Dynamical coherent states and physical solutions of quantum cosmological bounces
A new model is studied which describes the quantum behavior of transitions
through an isotropic quantum cosmological bounce in loop quantum cosmology
sourced by a free and massless scalar field. As an exactly solvable model even
at the quantum level, it illustrates properties of dynamical coherent states
and provides the basis for a systematic perturbation theory of loop quantum
gravity. The detailed analysis is remarkably different from what is known for
harmonic oscillator coherent states. Results are evaluated with regard to their
implications in cosmology, including a demonstration that in general quantum
fluctuations before and after the bounce are unrelated. Thus, even within this
solvable model the condition of classicality at late times does not imply
classicality at early times before the bounce without further assumptions.
Nevertheless, the quantum state does evolve deterministically through the
bounce.Comment: 30 pages, 3 figure
Similarity solutions of an equation describing ice sheet dynamics
This paper focus's upon the derivation of the similarity solutions of a free boundary problem arising in glaciology. With reference to shallow ice sheet flow we present a potential symmetry analysis of the second order non-linear degenerate parabolic equation that describe non-Newtonian ice sheet dynamics in the isothermal case. A full classical and also a non-classical symmetry analysis is presented. A particular example of a similarity solution to a problem formulated with Cauchy boundary conditions is described. This demonstrates the existence of a free moving boundary and also an accumulation-ablation function with realistic physical properties
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Quantifying the relative importance of land cover change from climate and land use in the representative concentration pathways
Climate change is projected to cause substantial alterations in vegetation distribution, but these have been given little attention in comparison to land-use in the Representative Concentration Pathway (RCP) scenarios. Here we assess the climate-induced land cover changes (CILCC) in the RCPs, and compare them to land-use land cover change (LULCC). To do this, we use an ensemble of simulations with and without LULCC in earth system model HadGEM2-ES for RCP2.6, RCP4.5 and RCP8.5. We find that climate change causes an expansion poleward of vegetation that affects more land area than LULCC in all of the RCPs considered here. The terrestrial carbon changes from CILCC are also larger than for LULCC. When considering only forest, the LULCC is larger, but the CILCC is highly variable with the overall radiative forcing of the scenario. The CILCC forest increase compensates 90% of the global anthropogenic deforestation by 2100 in RCP8.5, but just 3% in RCP2.6. Overall, bigger land cover changes tend to originate from LULCC in the shorter term or lower radiative forcing scenarios, and from CILCC in the longer term and higher radiative forcing scenarios. The extent to which CILCC could compensate for LULCC raises difficult questions regarding global forest and biodiversity offsetting, especially at different timescales. This research shows the importance of considering the relative size of CILCC to LULCC, especially with regard to the ecological effects of the different RCPs
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