8,507 research outputs found
Stellar Populations in the Outskirts of the Small Magellanic Cloud: No Outer Edge Yet
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 33\arcmin CMDs, that the age
composition of the stellar population is similar at galactocentric distances of
4.7 kpc, 5.6 kpc, and 6.5 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
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
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
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
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
Proteolytic processing of platelet receptors
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
https://thekeep.eiu.edu/eiu_bulletin/1193/thumbnail.jp
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