Zero temperature phase diagram of the square-shoulder system

Particles that interact via a square-shoulder potential, consisting of an impenetrable hard core with an adjacent, repulsive, step-like corona, are able to self-organize in a surprisingly rich variety of rather unconventional ordered structures. Using optimization strategies that are based on ideas of genetic algorithms we encounter, as we systematically increase the pressure, the following archetypes of aggregates: low-symmetry cluster and columnar phases, followed by lamellar particle arrangements, until at high pressure values compact, high-symmetry lattices emerge. These structures are characterized in the NPT ensemble as configurations of minimum Gibbs free energy. Based on simple considerations, i.e., basically minimizing the number of overlapping coronae while maximizing at the same time the density, the sequence of emerging structures can easily be understood.Comment: Submitted to J. Chem. Phy

Designing Place-sensitive Professional Development: A Critical Ethnography of Teaching and Learning Argumentative Writing

The purpose of this dissertation was to investigate the experiences of teachers participating in a two-year professional development program designed by the National Writing Project and funded by a U.S. Department of Education Investing in Innovation (i3) grant. Informed by New Literacy Studies’ ideological model of literacy as a Social practice and rural literacies’ notion of pedagogies of sustainability, this study employs critical ethnography and discourse analysis to analyze the discourse of teachers participating in the College-Ready Writers Program (CRWP) in order to understand how professional development might be adjusted to re-empower teachers. Data sources included field notes, interviews, lesson plans, student writing samples, and reflective vignettes, collected between March of 2013 and January of 2016. Data were analyzed in order to examine how teachers’ identities and epistemologies of literacy influenced their resistance or appropriation of the argumentative writing practices targeted by the CRWP professional development series. Analysis resulted in the identification of three essential themes in the discourse: (1) participating teachers who identified as writers and believed in their own instructional efficacy were more likely to successfully integrate argumentative writing into their curricula than teachers who did not identify readily as writers or had a generally low sense of instructional efficacy; (2) teachers who identified themselves as agents of change articulated and acted on beliefs in the expectancy-value theory, resulting in higher goals and higher expectations for students’ writing; and (3) for English language arts teachers working from epistemologies of literacy shaped by the understanding of literacy as a state of grace, the argumentative writing focus of the CRWP was outside of their disciplinary content area, a positioning that made integration challenging. These findings provide supporting evidence for the argument that professional development should invest in teachers’ empowerment through the exploration of their identities and epistemologies as a foundational step in the professional learning process

Magnetic Fields in Star-Forming Molecular Clouds I. The First Polarimetry of OMC-3 in Orion A

The first polarimetric images of the OMC-3 region of the Orion A filamentary molecular cloud are presented. Using the JCMT, we have detected polarized thermal emission at 850 microns from dust along a 6' length of the dense filament. The polarization pattern is highly ordered and is aligned with the filament throughout most of the region. The plane-of-sky magnetic field direction is perpendicular to the measured polarization. The mean percentage polarization is 4.2% with a 1 sigma dispersion of 1%. This region is part of the integral-shaped filament, and active star formation is ongoing along its length. The protostellar outflow directions do not appear to be consistently correlated with the direction of the plane-of-sky field or the filament structure itself. Depolarization toward the filament center, previously detected in many other star-forming cores and protostars, is also evident in our data. (abstract abridged)Comment: 9 pages plus 2 figures (1 colour); accepted for publication in the March 10, 2000 issue (vol. 531 #2) of The Astrophysical Journa

The Causal Interpretation of Quantum Mechanics and The Singularity Problem in Quantum Cosmology

We apply the causal interpretation of quantum mechanics to homogeneous quantum cosmology and show that the quantum theory is independent of any time-gauge choice and there is no issue of time. We exemplify this result by studying a particular minisuperspace model where the quantum potential driven by a prescribed quantum state prevents the formation of the classical singularity, independently on the choice of the lapse function. This means that the fast-slow-time gauge conjecture is irrelevant within the framework of the causal interpretation of quantum cosmology.Comment: 18 pages, LaTe

Comments on the Quantum Potential Approach to a Class of Quantum Cosmological Models

In this comment we bring attention to the fact that when we apply the ontological interpretation of quantum mechanics, we must be sure to use it in the coordinate representation. This is particularly important when canonical tranformations that mix momenta and coordinates are present. This implies that some of the results obtained by A. B\l aut and J. Kowalski-Glikman are incorrect.Comment: 7 pages, LaTe

HST/STIS Imaging of the Host Galaxy of GRB980425/SN1998bw

We present HST/STIS observations of ESO 184-G82, the host galaxy of the gamma-ray burst GRB 980425 associated with the peculiar Type Ic supernova SN1998bw. ESO 184-G82 is found to be an actively star forming SBc sub-luminous galaxy. We detect an object consistent with being a point source within the astrometric uncertainty of 0.018 arcseconds of the position of the supernova. The object is located inside a star-forming region and is at least one magnitude brighter than expected for the supernova based on a simple radioactive decay model. This implies either a significant flattening of the light curve or a contribution from an underlying star cluster.Comment: 12 pages, 2 figures, AASTeX v5.02 accepted for publication in ApJ Letter

Ceramides: a new player in the inflammation-insulin resistance paradigm?

No abstract available