Art, Artists and Pedagogy

This volume has been brought together to generate new ideas and provoke discussion about what constitutes arts education in the twenty-first century, both within the institution and beyond. Art, Artists and Pedagogy is intended for educators who teach the arts from early childhood to tertiary level, artists working in the community, or those studying arts in education from undergraduate to Masters or PhD level

High-Redshift Galaxies in Cold Dark Matter Models

We use hydrodynamic cosmological simulations to predict the star formation properties of high-redshift galaxies (z=2-6) in five variants of the inflationary cold dark matter scenario, paying particular attention to z=3, the redshift of the largest "Lyman-break galaxy" (LBG) samples. Because we link the star formation timescale to the local gas density, the rate at which a galaxy forms stars is governed mainly by the rate at which it accretes cooled gas from the surrounding medium. At z=3, star formation in most of the simulated galaxies is steady on 200 Myr timescales, and the instantaneous star formation rate (SFR) is correlated with total stellar mass. However, there is enough scatter in this correlation that a sample selected above a given SFR threshold may contain galaxies with a fairly wide range of masses. The redshift history and global density of star formation in the simulations depend mainly on the amplitude of mass fluctuations in the underlying cosmological model. The three models whose mass fluctuation amplitudes agree with recent analyses of the Lyman-alpha forest also reproduce the observed luminosity function of LBGs reasonably well, though the dynamic range of the comparison is small and the theoretical and observational uncertainties are large. The models with higher and lower amplitudes appear to predict too much and too little star formation, respectively, though they are not clearly ruled out. The intermediate amplitude models predict SFR ~ 30-40 Msun/yr for galaxies with a surface density 1 per arcmin^2 per unit redshift at z=3. They predict much higher surface densities at lower SFR, and significant numbers of galaxies with SFR > 10 Msun/yr at z >= 5.Comment: Submitted to ApJ. 31 pages including 10 ps figures. Full resolution version of Fig 2 available at http://www.astronomy.ohio-state.edu/~dhw/Sph/zgal.fig2.ps.g

Scale-dependent bias from primordial non-Gaussianity in general relativity

In this note we examine the derivation of scale-dependent bias due to primordial non-Gaussianity of the local type in the context of general relativity. We justify the use of the Poisson equation in general relativistic perturbation theory and thus the derivation of scale-dependent bias as a test of primordial non-Gaussianity, using the spherical collapse model. The corollary is that the form of scale-dependent bias does not receive general relativistic corrections on scales larger than the Hubble radius. This leads to a formally divergent correlation function for biased tracers of the mass distribution which we discuss.Comment: 6 pages; v2: added discussion of bias and spherical collapse in the longitudinal gauge; matches version accepted to PR

The Halo Occupation Distribution: Towards an Empirical Determination of the Relation Between Galaxies and Mass

We investigate galaxy bias in the framework of the ``Halo Occupation Distribution'' (HOD), which defines the bias of a population of galaxies by the conditional probability P(N|M) that a dark matter halo of virial mass M contains N galaxies, together with prescriptions that specify the relative spatial and velocity distributions of galaxies and dark matter within halos. By populating the halos of a cosmological N-body simulation using a variety of HOD models, we examine the sensitivity of different galaxy clustering statistics to properties of the HOD. The galaxy correlation function responds to different aspects of P(N|M) on different scales. Obtaining the observed power-law form of xi(r) requires rather specific combinations of HOD parameters, implying a strong constraint on the physics of galaxy formation; the success of numerical and semi-analytic models in reproducing this form is entirely non-trivial. Other clustering statistics such as the galaxy-mass correlation function, the bispectrum, the void probability function, the pairwise velocity dispersion, and the group multiplicity function are sensitive to different combinations of HOD parameters and thus provide complementary information about galaxy bias. We outline a strategy for determining the HOD empirically from redshift survey data. This method starts from an assumed cosmological model, but we argue that cosmological and HOD parameters will have non-degenerate effects on galaxy clustering, so that a substantially incorrect cosmological model will not reproduce the observations for any choice of HOD. Empirical determinations of the HOD as a function of galaxy type from the 2dF and SDSS redshift surveys will provide a detailed target for theories of galaxy formation, insight into the origin of galaxy properties, and sharper tests of cosmological models.Comment: 60 pages + 21 eps figures. Replaced with accepted ApJ version. Minor changes + added reference

Energy and Charged Particle Flow in 10.8 A GeV/c Au+Au Collisions

Experimental results and a detailed analysis are presented of the transverse energy and charged particle azimuthal distributions measured by the E877 collaboration for different centralities of Au+Au collisions at a beam momentum of 10.8 A GeV/c. The anisotropy of these distributions is studied with respect to the reaction plane reconstructed on an event-by-event basis using the transverse energy distribution measured by calorimeters. Results are corrected for the reaction plane resolution. For semicentral events we observe directed flow signals of up to ten percent. We observe a stronger anisotropy for slow charged particles. For both the charged particle and transverse energy distributions we observe a small but non zero elliptic anisotropy with the major axis pointing into the reaction plane. Combining the information on transverse energy and charged particle flow we obtain information on the flow of nucleons and pions. The data are compared to event generators and the need to introduce a mean field or nucleon-nucleon potential is discussed.Comment: RevTex, 25 pages, 13 figures included as one Postscript file, submitted to Phys. Rev.

Incorporating interactive 3-dimensional graphics in astronomy research papers

Most research data collections created or used by astronomers are intrinsically multi-dimensional. In contrast, all visual representations of data presented within research papers are exclusively 2-dimensional. We present a resolution of this dichotomy that uses a novel technique for embedding 3-dimensional (3-d) visualisations of astronomy data sets in electronic-format research papers. Our technique uses the latest Adobe Portable Document Format extensions together with a new version of the S2PLOT programming library. The 3-d models can be easily rotated and explored by the reader and, in some cases, modified. We demonstrate example applications of this technique including: 3-d figures exhibiting subtle structure in redshift catalogues, colour-magnitude diagrams and halo merger trees; 3-d isosurface and volume renderings of cosmological simulations; and 3-d models of instructional diagrams and instrument designs.Comment: 18 pages, 7 figures, submitted to New Astronomy. For paper with 3-dimensional embedded figures, see http://astronomy.swin.edu.au/s2plot/3dpd

Development of an Objective Structured Clinical Examination as a Component of Assessment for Initial Board Certification in Anesthesiology.

With its first administration of an Objective Structured Clinical Examination (OSCE) in 2018, the American Board of Anesthesiology (ABA) became the first US medical specialty certifying board to incorporate this type of assessment into its high-stakes certification examination system. The fundamental rationale for the ABA's introduction of the OSCE is to include an assessment that allows candidates for board certification to demonstrate what they actually "do" in domains relevant to clinical practice. Inherent in this rationale is that the OSCE will capture competencies not well assessed in the current written and oral examinations-competencies that will allow the ABA to judge whether a candidate meets the standards expected for board certification more properly. This special article describes the ABA's journey from initial conceptualization through first administration of the OSCE, including the format of the OSCE, the process for scenario development, the standardized patient program that supports OSCE administration, examiner training, scoring, and future assessment of reliability, validity, and impact of the OSCE. This information will be beneficial to both those involved in the initial certification process, such as residency graduate candidates and program directors, and others contemplating the use of high-stakes summative OSCE assessments

Dark Matter and Stellar Mass in the Luminous Regions of Disk Galaxies

We investigate the correlations among stellar mass (M_*), disk scale length (R_d), and rotation velocity at 2.2 disk scale lengths (V_2.2) for a sample of 81 disk-dominated galaxies (disk/total >= 0.9) selected from the SDSS. We measure V_2.2 from long-slit H-alpha rotation curves and infer M_* from galaxy i-band luminosities (L_i) and g-r colors. We find logarithmic slopes of 2.60+/-0.13 and 3.05+/-0.12 for the L_i-V_2.2 and M_*-V_2.2 relations, somewhat shallower than most previous studies, with intrinsic scatter of 0.13 dex and 0.16 dex. Our direct estimates of the total-to-stellar mass ratio within 2.2R_d, assuming a Kroupa IMF, yield a median ratio of 2.4 for M_*>10^10 Msun and 4.4 for M_*=10^9-10^10 Msun, with large scatter at a given M_* and R_d. The typical ratio of the rotation speed predicted for the stellar disk alone to the observed rotation speed at 2.2R_d is ~0.65. The distribution of R_d at fixed M_* is broad, but we find no correlation between disk size and the residual from the M_*-V_2.2 relation, implying that this relation is an approximately edge-on view of the disk galaxy fundamental plane. Independent of the assumed IMF, this result implies that stellar disks do not, on average, dominate the mass within 2.2R_d. We discuss our results in the context of infall models of disk formation in cold dark matter halos. A model with a disk-to-halo mass ratio m_d=0.05 provides a reasonable match to the R_d-M_* distribution for spin parameters \lambda ranging from ~0.04-0.08, and it yields a reasonable match to the mean M_*-V_2.2 relation. A model with m_d=0.1 predicts overly strong correlations between disk size and M_*-V_2.2 residual. Explaining the wide range of halo-to-disk mass ratios within 2.2R_d requires significant scatter in m_d values, with systematically lower m_d for galaxies with lower $M_*$.Comment: 18 pages, 2 tables, 7 figures, Accepted to ApJ, Table 1 updated, otherwise minor change