8,507 research outputs found

    Stellar Populations in the Outskirts of the Small Magellanic Cloud: No Outer Edge Yet

    Full text link
    We report the detection of intermediate-age and old stars belonging to the SMC at 6.5 kpc from the SMC center in the southern direction. We show, from the analysis of three high quality 34\arcmin ×\times 33\arcmin CMDs, that the age composition of the stellar population is similar at galactocentric distances of ∼\thicksim4.7 kpc, ∼\thicksim5.6 kpc, and ∼\thicksim6.5 kpc. The surface brightness profile of the SMC follows an exponential law, with no evidence of truncation, all the way out to 6.5 kpc. These results, taken together, suggest that the SMC `disk' population is dominating over a possible old Milky Way-like stellar halo, and that the SMC may be significantly larger than previously thought.Comment: Accepted for publication in ApJ Letters. High resolution figures are available at ftp://ftp.iac.es/out/noe

    Reflections of Practicing School Principals on Ethical Leadership and Decision-Making: Confronting Social Injustice

    Get PDF
    The study objective was to identify leadership dilemmas of practicing school administrators and their own codes of ethics to inform understandings of ethical decision-making. Ethical decision-making underpins leadership practice, theory, and preparation. Existing models for ethical leadership underplay the importance of social justice ethics in decision-making. The research encompassed a qualitative study based upon the constructivist paradigm. Data were collected in the form of interviews, document analyses, and professional observations with practicing school administrators in public schools. Dilemmas reported were analyzed utilizing ethical leadership theories together with social justice constructs. Results indicate ways practicing school administrators, faculty preparing administrators, and other business or organizational leaders can utilize ethical decision-making and leadership for organizational improvement

    Theory of the Ramsey spectroscopy and anomalous segregation in ultra-cold rubidium

    Full text link
    The recent anomalous segregation experiment of Lewandowski et al. (PRL, 88, 070403, 2002) shows dramatic, rapid internal state segregation for two hyperfine levels of rubidium. We simulate an effective one dimensional model of the system for experimental parameters and find reasonable agreement with the data. The Ramsey frequency is found to be insensitive to the decoherence of the superposition, and is only equivalent to the interaction energy shift for a pure superposition. A Quantum Boltzmann equation describing collisions is derived using Quantum Kinetic Theory, taking into account the different scattering lengths of the internal states. As spin-wave experiments are likely to be attempted at lower temperatures we examine the effect of degeneracy on decoherence by considering the recent experiment of Lewandowski et al. where degeneracy is around 10%. We also find that the segregation effect is only possible when transport terms are included in the equations of motion, and that the interactions only directly alter the momentum distributions of the states. The segregation or spin wave effect is thus entirely due to coherent atomic motion as foreseen in the experimental reportComment: 26 pages, 4 figures, to be published in J. Phys.

    Single photon state generation from a continuous-wave non-degenerate optical parametric oscillator

    Full text link
    We present a theoretical treatment of conditional preparation of one-photon states from a continuous-wave non-degenerate optical parametric oscillator. We obtain an analytical expression for the output state Wigner function, and we maximize the one-photon state fidelity by varying the temporal mode function of the output state. We show that a higher production rate of high fidelity Fock states is obtained if we condition the outcome on dark intervals around trigger photo detection events.Comment: 9 pages, 9 figures, v2: published versio

    The True Meaning of Going Armed in the Statute of Northampton: A Response to Patrick J. Charles

    Get PDF
    In the debate over the meaning of the right to keep and bear arms guaranteed by the Second Amendment, some writers have argued that the prohibition in the 1328 English Statute of Northampton on going armed referred to carrying weapons, thus purportedly showing that regulation of carrying weapons was well known and established when the Second Amendment was adopted. For the first time, this Article reveals, through a thorough analysis of medieval royal proclamations and acts of parliament, well-regarded legal treatises, literature of the time, and English case law, that going armed did not refer to carrying weapons, but rather to wearing armor. Accordingly, the Statute of Northampton does not show that regulation of carrying weapons was established at the time of the adoption of the Second Amendment

    AFES Circular 127

    Get PDF

    Proteolytic processing of platelet receptors

    Get PDF
    Platelets have a major role in hemostasis and an emerging role in biological processes including inflammation and immunity. Many of these processes require platelet adhesion and localization at sites of tissue damage or infection and regulated platelet activation, mediated by platelet adheso-signalling receptors, glycoprotein (GP) Ib-IX-V and GPVI. Work from a number of laboratories has demonstrated that levels of these receptors are closely regulated by metalloproteinases of the A Disintegrin And Metalloproteinase (ADAM) family, primarily ADAM17 and ADAM10. It is becoming increasingly evident that platelets have important roles in innate immunity, inflammation, and in combating infection that extends beyond processes of hemostasis. This overview will examine the molecular events that regulate levels of platelet receptors and then assess ramifications for these events in settings where hemostasis, inflammation, and infection processes are triggered.This work was supported by funds from the National Health and Medical Research Council of Australia, the National Blood Authority and ACT Health

    Bulletin 97 - The Use of Modern Poetry with Children, Second Edition

    Get PDF
    https://thekeep.eiu.edu/eiu_bulletin/1193/thumbnail.jp
    • …
    corecore