Measuring Effective Tax Rates on Human Capital: Methodology and an Application to Canada

This paper examines the impacts of a wide range of tax provisions on the incentive to invest in human capital, and shows how these effects can be quantified using effective tax rates, or ETRs. For individuals with median earnings, ETRs on the human capital formed in first-degree university study are sizeable, although not as large as those estimated by previous authors for physical capital in Canada. When the expenditure side and its direct subsidies are also taken into account, the net effective tax rate on human capital becomes negative. The taxation of human capital is far from uniform. ETRs vary by income level, gender, part-time vs. full-time study, whether students have loans, number of dependants, and use of RESPs. The most significant differences are those related to income level. Workers at higher percentile levels of the earnings distribution throughout life may face ETRs three times as high as those for low-income workers – a result of our progressive income tax system.

Overlooked examples of cloud self-organization at the mesoscale

Stratocumulus clouds are common in the tropical and subtropical marine boundary layer, and understanding these clouds is important due to their significant impact on the earth's radiation budget. Observations show that the marine boundary layer contains complex, but poorly understood processes, which, from time to time, result in the observable self-organization of cloud structures at scales ranging from a few to a few thousand kilometers. Such shallow convective cloud features, typically observed as hexagonal cells, are known generally as mesoscale cellular convection (MCC). Actinoform clouds are rarer, but visually more striking forms of MCC, which possess a radial structure. Because mesoscale cloud features are typically too large to be observed from the ground, observations of hexagonal cells historically date only to the beginning of satellite meteorology. Examples of actinoform clouds were shown in the venerable “Picture of the Month” series in Monthly Weather Review in the early 1960s, but these clouds were generally forgotten as research focused on hexagonal cells. Recent high-resolution satellite images have, in a sense, “rediscovered” actinoform clouds, and they appear to be much more prevalent than had been previously suspected. We show a number of examples of actinoform clouds from a variety of locations worldwide. In addition, we have conducted a detailed case study of an actinoform cloud system using data from the Multiangle Imaging SpectroRadiometer (MISR) and the Geostationary Operational Environmental Satellite (GOES), including analysis of cloud heights, radiative properties, and the time-evolution of the cloud system. We also examine earlier theories regarding actinoform clouds in light of the new satellite data

Optical/near-infrared colours of early-type galaxies and constraints on their star formation histories

(abridged) We introduce and discuss the properties of a theoretical (B-K)-(J-K) integrated colour diagram for single-age, single-metallicity stellar populations. This combination of integrated colours is able to largely disentangle the well known age-metallicity degeneracy when the age of the population is greater than ~300 Myr. We discuss in detail the effect on this colour-colour diagram of alpha-enhanced metal abundance ratios, the presence of blue horizontal branch stars unaccounted for in the theoretical calibration, and of statistical colour fluctuations in low mass stellar systems. In the case of populations with multiple stellar generations, the luminosity-weighted mean age obtained from this diagram is shown to be heavily biased towards the youngest stellar components. We apply this method to several datasets for which optical and near-IR photometry are available in the literature. For the two Local Group dwarf galaxies NGC185 and NGC6822, the mean ages derived from the integrated colours are consistent with the star formation histories inferred independently from photometric observations of their resolved stellar populations. A sample of bright field and Virgo cluster elliptical galaxies is found to exhibit a range of luminosity-weighted mean ages from 3 to 14 Gyr, with a mean of 8 Gyr, independent of environment, and mean metallicities at or just above the solar value. Colour gradients are found in all of the galaxies studied, in the sense that central regions are redder. Aperture data for five Virgo early-type dwarf galaxies show that these galaxies appear to be shifted to lower mean metallicities and lower mean ages (range 1 to 6 Gyr) than their higher luminosity counterparts.Comment: (1) Liverpool John Moores University, UK; (2) University of Cardiff, UK; (3) University of Bristol, UK; (4) INAF-Osservatorio Astronomico di Collurania, I; 12 pages, 9 figures, MNRAS in pres

Virtual patient design : exploring what works and why : a grounded theory study

Objectives: Virtual patients (VPs) are online representations of clinical cases used in medical education. Widely adopted, they are well placed to teach clinical reasoning skills. International technology standards mean VPs can be created, shared and repurposed between institutions. A systematic review has highlighted the lack of evidence to support which of the numerous VP designs may be effective, and why. We set out to research the influence of VP design on medical undergraduates. Methods: This is a grounded theory study into the influence of VP design on undergraduate medical students. Following a review of the literature and publicly available VP cases, we identified important design properties. We integrated them into two substantial VPs produced for this research. Using purposeful iterative sampling, 46 medical undergraduates were recruited to participate in six focus groups. Participants completed both VPs, an evaluation and a 1-hour focus group discussion. These were digitally recorded, transcribed and analysed using grounded theory, supported by computer-assisted analysis. Following open, axial and selective coding, we produced a theoretical model describing how students learn from VPs. Results: We identified a central core phenomenon designated ‘learning from the VP’. This had four categories: VP Construction; External Preconditions; Student–VP Interaction, and Consequences. From these, we constructed a three-layer model describing the interactions of students with VPs. The inner layer consists of the student's cognitive and behavioural preconditions prior to sitting a case. The middle layer considers the VP as an ‘encoded object’, an e-learning artefact and as a ‘constructed activity’, with associated pedagogic and organisational elements. The outer layer describes cognitive and behavioural change. Conclusions: This is the first grounded theory study to explore VP design. This original research has produced a model which enhances understanding of how and why the delivery and design of VPs influence learning. The model may be of practical use to authors, institutions and researchers

Primary accumulation in the Soviet transition

The Soviet background to the idea of primary socialist accumulation is presented. The mobilisation of labour power and of products into public sector investment from outside are shown to have been the two original forms of the concept. In Soviet primary accumulation the mobilisation of labour power was apparently more decisive than the mobilisation of products. The primary accumulation process had both intended and unintended results. Intended results included bringing most of the economy into the public sector, and industrialisation of the economy as a whole. Unintended results included substantial economic losses, and the proliferation of coercive institutions damaging to attainment of the ultimate goal - the building of a communist society

Low Luminosity States of the Black Hole Candidate GX~339--4. II. Timing Analysis

Here we present timing analysis of a set of eight Rossi X-ray Timing Explorer (RXTE) observations of the black hole candidate GX 339-4 that were taken during its hard/low state. On long time scales, the RXTE All Sky Monitor data reveal evidence of a 240 day periodicity, comparable to timescales expected from warped, precessing accretion disks. On short timescales all observations save one show evidence of a persistent f approximately equal to 0.3 Hz QPO. The broad band (10^{-3}-10^2 Hz) power appears to be dominated by two independent processes that can be modeled as very broad Lorentzians with Q approximately less than 1. The coherence function between soft and hard photon variability shows that if these are truly independent processes, then they are individually coherent, but they are incoherent with one another. This is evidenced by the fact that the coherence function between the hard and soft variability is near unity between 0.005-10 Hz but shows evidence of a dip at f approximately equal to 1 Hz. This is the region of overlap between the broad Lorentzian fits to the PSD. Similar to Cyg X-1, the coherence also drops dramatically at frequencies approximately greater than 10 Hz. Also similar to Cyg X-1, the hard photon variability is seen to lag the soft photon variability with the lag time increasing with decreasing Fourier frequency. The magnitude of this time lag appears to be positively correlated with the flux of GX 339-4. We discuss all of these observations in light of current theoretical models of both black hole spectra and temporal variability.Comment: To Appear in the AStrophysical Journa

Interactions of asbestos-activated macrophages with an experimental fibrosarcoma

Supernatants from in vivo asbestos-activated macrophages failed to show any cytostatic activity against a syngeneic fibrosarcoma cell line in vitro. UICC chrysotile-induced peritoneal exudate cells also failed to demonstrate any growth inhibitory effect on the same cells in Winn assays of tumor growth. Mixing UICC crocidolite with inoculated tumor cells resulted in a dose-dependent inhibition of tumor growth; this could, however, be explained by a direct cytostatic effect on the tumor cells of high doses of crocidolite, which was observed in vitro

A Survey for Planetary Nebulae in M31 Globular Clusters

We report the results of an [O III] 5007 spectroscopic survey for planetary nebulae (PNe) located within the star clusters of M31. By examining R ~ 5000 spectra taken with the WIYN+Hydra spectrograph, we identify 3 PN candidates in a sample of 274 likely globular clusters, 2 candidates in objects which may be globular clusters, and 5 candidates in a set of 85 younger systems. The possible PNe are all faint, between ~2.5 and ~6.8 mag down the PN luminosity function, and, partly as a consequence of our selection criteria, have high excitation, with [O III] 5007 to H-beta ratios ranging from 2 to ~12. We discuss the individual candidates, their likelihood of cluster membership, and the possibility that they were formed via binary interactions within the clusters. Our data are consistent with the suggestion that PN formation within globular clusters correlates with binary encounter frequency, though, due to the small numbers and large uncertainties in the candidate list, this study does not provide sufficient evidence to confirm the hypothesis.Comment: Accepted for publication in the Astrophysical Journal. 54 pages, including 9 figures and 4 table