Critical Reflection and Imaginative Engagement: Towards an Integrated Theory of Transformative Learning

Based on a review of the literature, we propose an integrated approach to transformative learning that recognizes the importance of both the rational and affective, as well as the personal and the social dimensions in fostering self-understanding

Maximum Entropy Analysis of Flow Networks: Theoretical Foundation and Applications

The concept of a “flow network”—a set of nodes and links which carries one or more flows—unites many different disciplines, including pipe flow, fluid flow, electrical, chemical reaction, ecological, epidemiological, neurological, communications, transportation, financial, economic and human social networks. This Feature Paper presents a generalized maximum entropy framework to infer the state of a flow network, including its flow rates and other properties, in probabilistic form. In this method, the network uncertainty is represented by a joint probability function over its unknowns, subject to all that is known. This gives a relative entropy function which is maximized, subject to the constraints, to determine the most probable or most representative state of the network. The constraints can include “observable” constraints on various parameters, “physical” constraints such as conservation laws and frictional properties, and “graphical” constraints arising from uncertainty in the network structure itself. Since the method is probabilistic, it enables the prediction of network properties when there is insufficient information to obtain a deterministic solution. The derived framework can incorporate nonlinear constraints or nonlinear interdependencies between variables, at the cost of requiring numerical solution. The theoretical foundations of the method are first presented, followed by its application to a variety of flow networks

Clinical reasoning: What do nurses, physicians, and students reason about.

Clinical reasoning is a core ability in the health professions, but the term is conceptualised in multiple ways within and across professions. For interprofessional teamwork it is indispensable to recognise the differences in understanding between professions. Therefore, our aim was to investigate how nurses, physicians, and medical and nursing students define clinical reasoning. We conducted 43 semi-structured interviews with an interprofessional group from six countries and qualitatively analysed their definitions of clinical reasoning based on a coding guide. Our results showed similarities across professions, such as the emphasis on clinical skills as part of clinical reasoning. But we also revealed differences, such as a more patient-centered view and a broader understanding of the clinical reasoning concept in nurses and nursing students. The explicit sharing and discussion of differences in the understanding of clinical reasoning across health professions can provide valuable insights into the perspectives of different team members on clinical practice and education. This understanding may lead to improved interprofessional collaboration, and our study's categories and themes can serve as a basis for such discussions

Group finding in the stellar halo using M-giants in 2MASS: An extended view of the Pisces Overdensity?

A density based hierarchical group-finding algorithm is used to identify stellar halo structures in a catalog of M-giants from the Two Micron All Sky Survey (2MASS). The intrinsic brightness of M-giant stars means that this catalog probes deep into the halo where substructures are expected to be abundant and easy to detect. Our analysis reveals 16 structures at high Galactic latitude (greater than 15 degree), of which 10 have been previously identified. Among the six new structures two could plausibly be due to masks applied to the data, one is associated with a strong extinction region and one is probably a part of the Monoceros ring. Another one originates at low latitudes, suggesting some contamination from disk stars, but also shows protrusions extending to high latitudes, implying that it could be a real feature in the stellar halo. The last remaining structure is free from the defects discussed above and hence is very likely a satellite remnant. Although the extinction in the direction of the structure is very low, the structure does match a low temperature feature in the dust maps. While this casts some doubt on its origin, the low temperature feature could plausibly be due to real dust in the structure itself. The angular position and distance of this structure encompass the Pisces overdensity traced by RR Lyraes in Stripe 82 of the Sloan Digital Sky Survey (SDSS). However, the 2MASS M-giants indicate that the structure is much more extended than what is visible with the SDSS, with the point of peak density lying just outside Stripe 82. The morphology of the structure is more like a cloud than a stream and reminiscent of that seen in simulations of satellites disrupting along highly eccentric orbits.Comment: Accepted for publication in Ap

Lifting the Dusty Veil With Near- and Mid-Infrared Photometry: III. Two-Dimensional Extinction Maps of the Galactic Midplane Using the Rayleigh-Jeans Color Excess Method

We provide new, high-resolution A(Ks) extinction maps of the heavily reddened Galactic midplane based on the Rayleigh-Jeans Color Excess ("RJCE") method. RJCE determines star-by-star reddening based on a combination of near- and mid-infrared photometry. The new RJCE-generated maps have 2 x 2 arcmin pixels and span some of the most severely extinguished regions of the Galaxy -- those covered with Spitzer+IRAC imaging by the GLIMPSE-I, -II, -3D, and Vela-Carina surveys, from 256<l<65 deg and, in general, for |b| <= 1-1.5 deg (extending up to |b|<=4 deg in the bulge). Using RJCE extinction measurements, we generate dereddened color-magnitude diagrams and, in turn, create maps based on main sequence, red clump, and red giant star tracers, each probing different distances and thereby providing coarse three-dimensional information on the relative placement of dust cloud structures. The maps generated from red giant stars, which reach to ~18-20 kpc, probe beyond most of the Milky Way extinction in most directions and provide close to a "total Galactic extinction" map -- at minimum they provide high angular resolution maps of lower limits on A(Ks). Because these maps are generated directly from measurements of reddening by the very dust being mapped, rather than inferred on the basis of some less direct means, they are likely the most accurate to date for charting in detail the highly patchy differential extinction in the Galactic midplane. We provide downloadable FITS files and an IDL tool for retrieving extinction values for any line of sight within our mapped regions.Comment: 23 pages, 5 figures, accepted for publication in ApJ

The Connection Between Diffuse Light and Intracluster Planetary Nebulae in the Virgo Cluster

We compare the distribution of diffuse intracluster light detected in the Virgo Cluster via broadband imaging with that inferred from searches for intracluster planetary nebulae (IPNe). We find a rough correspondence on large scales (~ 100 kpc) between the two, but with very large scatter (~ 1.3 mag/arcsec^2). On smaller scales (1 -- 10 kpc), the presence or absence of correlation is clearly dependent on the underlying surface brightness. On these scales, we find a correlation in regions of higher surface brightness (mu_V < ~27) which are dominated by the halos of large galaxies such as M87, M86, and M84. In those cases, we are likely tracing PNe associated with galaxies rather than true IPNe. In true intracluster fields, at lower surface brightness, the correlation between luminosity and IPN candidates is much weaker. While a correlation between broadband light and IPNe is expected based on stellar populations, a variety of statistical, physical, and methodological effects can act to wash out this correlation and explain the lack of a strong correlation at lower surface brightness found here. [abridged

Proper Motions in Kapteyn Selected Area 103: A Preliminary Orbit for the Virgo Stellar Stream

We present absolute proper motions in Kapteyn Selected Area (SA) 103. This field is located 7 degrees west of the center of the Virgo Stellar Stream (VSS, Duffau et al. 2006), and has a well-defined main sequence representing the stream. In SA 103 we identify one RR Lyrae star as a member of the VSS according to its metallicity, radial velocity and distance. VSS candidate turnoff stars and subgiant stars have proper motions consistent with that of the RR Lyrae star. The 3D velocity data imply an orbit with a pericenter of 11 kpc and an apocenter of ~90 kpc. Thus, the VSS comprises tidal debris found near the pericenter of a highly destructive orbit. Examining the six globular clusters at distances larger than 50 kpc from the Galactic center, and the proposed orbit of the VSS, we find one tentative association, NGC 2419. We speculate that NGC 2419 is possibly the nucleus of a disrupted system of which the VSS is a part.Comment: ApJL accepte

The Extended Star Formation History of the Andromeda Spheroid at 35 Kpc on the Minor Axis

Using the HST ACS, we have obtained deep optical images reaching well below the oldest main sequence turnoff in fields on the southeast minor-axis of the Andromeda Galaxy, 35 kpc from the nucleus. These data probe the star formation history in the extended halo of Andromeda -- that region beyond 30 kpc that appears both chemically and morphologically distinct from the metal-rich, highly-disturbed inner spheroid. The present data, together with our previous data for fields at 11 and 21 kpc, do not show a simple trend toward older ages and lower metallicities, as one might expect for populations further removed from the obvious disturbances of the inner spheroid. Specifically, the mean ages and [Fe/H] values at 11 kpc, 21 kpc, and 35 kpc are 9.7 Gyr and -0.65, 11.0 Gyr and -0.87, and 10.5 Gyr and -0.98, respectively. In the best-fit model of the 35 kpc population, one third of the stars are younger than 10 Gyr, while only ~10% of the stars are truly ancient and metal-poor. The extended halo thus exhibits clear evidence of its hierarchical assembly, and the contribution from any classical halo formed via early monolithic collapse must be small.Comment: Accepted for publication in The Astrophysical Journal Letters. 4 pages, latex, 2 color figure

Lifting the Dusty Veil With Near- and Mid-Infrared Photometry: I. Description and Applications of the Rayleigh-Jeans Color Excess Method

The Milky Way (MW) remains a primary laboratory for understanding the structure and evolution of spiral galaxies, but typically we are denied clear views of MW stellar populations at low Galactic latitudes because of extinction by interstellar dust. However, the combination of 2MASS near-infrared (NIR) and Spitzer-IRAC mid-infrared (MIR) photometry enables a powerful method for determining the line of sight reddening to any star: the sampled wavelengths lie in the Rayleigh-Jeans part of the spectral energy distribution of most stars, where, to first order, all stars have essentially the same intrinsic color. Thus, changes in stellar NIR-MIR colors due to interstellar reddening are readily apparent, and (under an assumed extinction law) the observed colors and magnitudes of stars can be easily and accurately restored to their intrinsic values, greatly increasing their usefulness for Galactic structure studies. In this paper we explore this "Rayleigh-Jeans Color Excess" (RJCE) method and demonstrate that use of even a simple variant of the RJCE method based on a single reference color, (H-[4.5um]), can rather accurately remove dust effects from previously uninterpretable 2MASS color-magnitude diagrams of stars in fields along the heavily reddened Galactic mid-plane, with results far superior to those derived from application of other dereddening methods. We also show that "total" Galactic midplane extinction looks rather different from that predicted using 100um emission maps from the IRAS/ISSA and COBE/DIRBE instruments as presented by Schlegel et al. Instead, the Galactic mid-plane extinction strongly resembles the distribution of 13-CO (J=1->0) emission. Future papers will focus on refining the RJCE method and applying the technique to understand better not only dust and its distribution, but the distribution of stars intermixed with the dust in the low-latitude Galaxy.Comment: Accepted to ApJ; 21 pages, 17 figure

The nature of the dwarf population in Abell 868

We present the results of a study of the morphology of the dwarf galaxy population in Abell 868, a rich, intermediate redshift (z=0.154) cluster which has a galaxy luminosity function with a steep faint-end slope (alpha=-1.26 +/- 0.05). A statistical background subtraction method is employed to study the B-R colour distribution of the cluster galaxies. This distribution suggests that the galaxies contributing to the faint-end of the measured cluster LF can be split into three populations: dIrrs with B-R<1.4; dEs with 1.4<B-R<2.5; and contaminating background giant ellipticals (gEs) with B-R>2.5. The remvoal of the contribution of the background gEs from the counts only marginally lessens the faint-end slope (alpha=-1.22 +/- 0.16). However, the removal of the contribution of the dIrrs from the counts produces a flat LF (alpha=-0.91 +/- 0.16). The dEs and the dIrrs have similar spatial distributions within the cluster except that the dIrrs appear to be totally absent within a central projected radius of about 0.2 Mpc (Ho=75 km/s /Mpc). The number density of both dEs and dIrrs appear to fall off beyond a projected radius of about 0.35 Mpc. We suggest that the dE and dIrr populations of A868 have been associated with the cluster for similar timescales but that evolutionary processes such as `galaxy harassment' tend to fade the dIrr galaxies while having much less effect on the dE galaxies. The harassement would be expected to have the greatest effect on dwarfs residing in the central parts of the cluster.Comment: 6 pages, 6 figures To be published in The Monthly Notices of the Royal Astronomical Societ