Evaluating the Effectiveness of tutorial dialogue instruction in a Explotary learning context

[Proceedings of] ITS 2006, 8th International Conference on Intelligent Tutoring Systems, 26-30 June 2006, Jhongli, Taoyuan County, TaiwanIn this paper we evaluate the instructional effectiveness of tutorial dialogue agents in an exploratory learning setting. We hypothesize that the creative nature of an exploratory learning environment creates an opportunity for the benefits of tutorial dialogue to be more clearly evidenced than in previously published studies. In a previous study we showed an advantage for tutorial dialogue support in an exploratory learning environment where that support was administered by human tutors [9]. Here, using a similar experimental setup and materials, we evaluate the effectiveness of tutorial dialogue agents modeled after the human tutors from that study. The results from this study provide evidence of a significant learning benefit of the dialogue agentsThis project is supported by ONR Cognitive and Neural Sciences Division, Grant number N000140410107proceedingPublicad

Utilising highly characterised peats to remove cadmium from aqueous solutions

This research investigated the biosorption of cadmium (Cd) from aqueous solutions by six highly characterised peats. Samples of the peats were tested both in unaltered condition and after treatment with hydrochloric acid (HCl) to free up any occupied exchange sites. Other factors tested were sample dose, contact time, mixing temperature, and the concentration and pH of the Cd solution. Desorption studies were also performed, and tests were done to determine whether the peats could be re-used for Cd biosorption. The results indicate that all six peats biosorb Cd from aqueous solution well (36−100 % removal) and that their Cd removal capacities are affected by the various factors that were manipulated. The three factors that had the greatest effects on the Cd removal capacities of the peats were sample dose and the concentration and pH of the Cd solution. The percentage of Cd removed increased as the sample dose increased (16−31 % increase) and as the pH of the Cd solution increased (16−57 % increase). As the concentration of the Cd solution increased, the percentage of Cd removed increased slightly for two of the six peats (1−2 % increase) and decreased for three peats (19−23 % decrease). As the mixing temperature increased, the percentage of Cd removed increased slightly for three of the peats (1−12 % increase) and decreased slightly for the other three (1−5 % decrease). The desorption results showed a 34−71 % Cd recovery rate. Re-used peats were also highly effective at removing Cd, whether or not they had gone through desorption. Two of the six peats were slightly better at Cd removal after treatment with HCl (4−7 % better than untreated peats), while the other four peats worked better in their unaltered states (3−18 % better). As all of the peat types tested can be repeatedly re-used for additional Cd biosorption cycles, their disposal should not create a hazardous waste problem. On the other hand, using peat for any industrial purpose is increasingly disfavoured nowadays, for sustainability reasons. Thus, the results of this study might be used to identify and/or develop materials with properties similar to those of the most effective peats (i.e. artificial peats) for use as biosorbents of Cd. These materials could be agricultural waste products such as soybean or rice hulls, constructed wetlands with living plants similar to those found in the tested peats, or possibly biochar of these living plants

Young star clusters in M31

In our study of M31's globular cluster system with MMT/Hectospec, we have obtained high-quality spectra of 85 clusters with ages less than 1 Gyr. With the exception of Hubble V, the young cluster in NGC 205, we find that these young clusters have kinematics and spatial distribution consistent with membership in M31's young disk. Preliminary estimates of the cluster masses and structural parameters, using spectroscopically derived ages and HST imaging, confirms earlier suggestions that M31 has clusters similar to the LMC's young populous clusters.Comment: 4 pages, 1 figure, contributed talk at "Galaxies in the Local Volume" conference in Sydney, July 200

Global Properties of fp-Shell Interactions in Many-nucleon Systems

Spectral distribution theory, which can be used to compare microscopic interactions over a broad range of nuclei, is applied in an analysis of two modern effective interactions based on the realistic CD-Bonn potential for $0\hbar\Omega$ no-core shell model calculations in the fp shell, as well as in a comparison of these with the realistic shell-model GXPF1 interaction. In particular, we explore the ability of these interaction to account for the development of isovector pairing correlations and collective rotational motion in the fp shell. Our findings expose the similarities of these two-body interactions, especially as this relates to their pairing and rotational characteristics. Further, the GXPF1 interaction is used to determine the strength parameter of a quadrupole term that can be used to augment an isovector-pairing model interaction with Sp(4) dynamical symmetry, which in turn is shown to yield reasonable agreement with the low-lying energy spectra of $^{58}$Ni and $^{58}$Cu.Comment: 21 pages, 3 figures, accepted in Nuclear Physics

The significance of 'the visit' in an English category-B prison: Views from prisoners, prisoners' families and prison staff

A number of claims have been made regarding the importance of prisoners staying in touch with their family through prison visits, firstly from a humanitarian perspective of enabling family members to see each other, but also regarding the impact of maintaining family ties for successful rehabilitation, reintegration into society and reduced re-offending. This growing evidence base has resulted in increased support by the Prison Service for encouraging the family unit to remain intact during a prisoner’s incarceration. Despite its importance however, there has been a distinct lack of research examining the dynamics of families visiting relatives in prison. This paper explores perceptions of the same event – the visit – from the families’, prisoners’ and prison staffs' viewpoints in a category-B local prison in England. Qualitative data was collected with 30 prisoners’ families, 16 prisoners and 14 prison staff, as part of a broader evaluation of the visitors’ centre. The findings suggest that the three parties frame their perspective of visiting very differently. Prisoners’ families often see visits as an emotional minefield fraught with practical difficulties. Prisoners can view the visit as the highlight of their time in prison and often have many complaints about how visits are handled. Finally, prison staff see visits as potential security breaches and a major organisational operation. The paper addresses the current gap in our understanding of the prison visit and has implications for the Prison Service and wider social policy

Molecular dynamics simulation of the order-disorder phase transition in solid NaNO2_2

We present molecular dynamics simulations of solid NaNO$_2$ using pair potentials with the rigid-ion model. The crystal potential surface is calculated by using an \emph{a priori} method which integrates the \emph{ab initio} calculations with the Gordon-Kim electron gas theory. This approach is carefully examined by using different population analysis methods and comparing the intermolecular interactions resulting from this approach with those from the \emph{ab initio} Hartree-Fock calculations. Our numerics shows that the ferroelectric-paraelectric phase transition in solid NaNO$_2$ is triggered by rotation of the nitrite ions around the crystallographical c axis, in agreement with recent X-ray experiments [Gohda \textit{et al.}, Phys. Rev. B \textbf{63}, 14101 (2000)]. The crystal-field effects on the nitrite ion are also addressed. Remarkable internal charge-transfer effect is found.Comment: RevTeX 4.0, 11 figure

First-principles study of the ferroelastic phase transition in CaCl_2

First-principles density-functional calculations within the local-density approximation and the pseudopotential approach are used to study and characterize the ferroelastic phase transition in calcium chloride (CaCl_2). In accord with experiment, the energy map of CaCl_2 has the typical features of a pseudoproper ferroelastic with an optical instability as ultimate origin of the phase transition. This unstable optic mode is close to a pure rigid unit mode of the framework of chlorine atoms and has a negative Gruneisen parameter. The ab-initio ground state agrees fairly well with the experimental low temperature structure extrapolated at 0K. The calculated energy map around the ground state is interpreted as an extrapolated Landau free-energy and is successfully used to explain some of the observed thermal properties. Higher-order anharmonic couplings between the strain and the unstable optic mode, proposed in previous literature as important terms to explain the soft-phonon temperature behavior, are shown to be irrelevant for this purpose. The LAPW method is shown to reproduce the plane-wave results in CaCl_2 within the precision of the calculations, and is used to analyze the relative stability of different phases in CaCl_2 and the chemically similar compound SrCl_2.Comment: 9 pages, 6 figures, uses RevTeX

A Parametric Study of Erupting Flux Rope Rotation. Modeling the "Cartwheel CME" on 9 April 2008

The rotation of erupting filaments in the solar corona is addressed through a parametric simulation study of unstable, rotating flux ropes in bipolar force-free initial equilibrium. The Lorentz force due to the external shear field component and the relaxation of tension in the twisted field are the major contributors to the rotation in this model, while reconnection with the ambient field is of minor importance. Both major mechanisms writhe the flux rope axis, converting part of the initial twist helicity, and produce rotation profiles which, to a large part, are very similar in a range of shear-twist combinations. A difference lies in the tendency of twist-driven rotation to saturate at lower heights than shear-driven rotation. For parameters characteristic of the source regions of erupting filaments and coronal mass ejections, the shear field is found to be the dominant origin of rotations in the corona and to be required if the rotation reaches angles of order 90 degrees and higher; it dominates even if the twist exceeds the threshold of the helical kink instability. The contributions by shear and twist to the total rotation can be disentangled in the analysis of observations if the rotation and rise profiles are simultaneously compared with model calculations. The resulting twist estimate allows one to judge whether the helical kink instability occurred. This is demonstrated for the erupting prominence in the "Cartwheel CME" on 9 April 2008, which has shown a rotation of \approx 115 degrees up to a height of 1.5 R_sun above the photosphere. Out of a range of initial equilibria which include strongly kink-unstable (twist Phi=5pi), weakly kink-unstable (Phi=3.5pi), and kink-stable (Phi=2.5pi) configurations, only the evolution of the weakly kink-unstable flux rope matches the observations in their entirety.Comment: Solar Physics, submitte

Naked Singularity Formation In f(R) Gravity

We study the gravitational collapse of a star with barotropic equation of state $p=w\rho$ in the context of $f({\mathcal R})$ theories of gravity. Utilizing the metric formalism, we rewrite the field equations as those of Brans-Dicke theory with vanishing coupling parameter. By choosing the functionality of Ricci scalar as $f({\mathcal R})=\alpha{\mathcal R}^{m}$, we show that for an appropriate initial value of the energy density, if $\alpha$ and $m$ satisfy certain conditions, the resulting singularity would be naked, violating the cosmic censorship conjecture. These conditions are the ratio of the mass function to the area radius of the collapsing ball, negativity of the effective pressure, and the time behavior of the Kretschmann scalar. Also, as long as parameter $\alpha$ obeys certain conditions, the satisfaction of the weak energy condition is guaranteed by the collapsing configuration.Comment: 15 pages, 4 figures, to appear in GR