607 research outputs found
Stellar Forensics II: Millisecond Pulsar Binaries
We use the grid of models described in paper~I to analyse those millisecond
pulsar binaries whose secondaries have been studied optically. In particular,
we find cooling ages for these binary systems that range from to
. Comparison of cooling ages and characteristic spin down ages
allows us to constrain the initial spin periods and spin-up histories for
individual systems, showing that at least some millisecond pulsars had
sub-Eddington accretion rates and long magnetic field decay times.Comment: Latex, 14 pages, and 15 postscript figures. Accepted by Monthly
Notice
The Pulsar Kick Velocity Distribution
We analyse the sample of pulsar proper motions, taking detailed account of
the selection effects of the original surveys. We treat censored data using
survival statistics. From a comparison of our results with Monte Carlo
simulations, we find that the mean birth speed of a pulsar is 250-300 km/s,
rather than the 450 km/s foundby Lyne & Lorimer (1994). The resultant
distribution is consistent with a maxwellian with dispersion . Despite the large birth velocities, we find that the pulsars with long
characteristic ages show the asymmetric drift, indicating that they are
dynamically old. These pulsars may result from the low velocity tail of the
younger population, although modified by their origin in binaries and by
evolution in the galactic potential.Comment: Latex, 10 pages, and 11 postscript figures. Accepted by Monthly
Notice
La Freccia Rossa: An IR-dark cloud hosting the Milky Way intermediate-mass black hole candidate
The dynamics of the high-velocity compact molecular cloud CO-0.40-0.22 have
been interpreted as evidence for a black hole within 60
pc of Sgr A*. Recently, Oka et al. have identified a compact
millimetre-continuum source, CO-0.40-0.22*, with this candidate black hole.
Here we present a collation of radio and infrared data at this location. ATCA
constraints on the radio spectrum, and the detection of a mid-infrared
counterpart, are in tension with an Sgr A*-like model for CO-0.40-0.22* despite
the comparable bolometric to Eddington luminosity ratios under the IMBH
interpretation. A protostellar-disk scenario is, however, tenable.
CO-0.40-0.22(*) is associated with an arrowhead-shaped infrared-dark cloud
(which we call the Freccia Rossa). Radio-continuum observations reveal a
candidate HII region associated with the system. If the
km s systemic velocity of CO-0.40-0.22 is common to the entire Freccia
Rossa system, we hypothesise that it is the remnant of a high-velocity cloud
that has plunged into the Milky Way from the Galactic halo.Comment: 6 pages, 3 figures, submitted to MNRAS Letter
LEAN Government Initiatives and the Origins of Administrative Reforms
Government has both tremendous power and responsibility in modern American society. Throughout history, the role of government has shifted with the emergence of new programs and policies. Beginning in the late 1800’s, the role of government expanded with the mass production of railroads and rapid economic development. With this expansion of government, scholars such as Woodrow Wilson turned their attention to the performance of our national bureaucracy, arguing that administration of public policies could be more successful if reforms were instituted. The trend of administrative expansion accelerated into the 20th Century while conducting two major wars and in responding to the Great Depression. The expansion of the administrative state meant that scholars, policymakers, and citizens now had to respond to a more powerful national government that was expensive to maintain. Conservatives adopted a narrative, most successfully advanced by the Reagan Administration, that American government had grown too large and inefficient, causing confidence in the federal government to diminish among American citizens. This lack of confidence still poses significant challenges to policymakers who seek to use government in more positive ways. Recognizing that Republicans were capitalizing politically on the American electorate’s lack of confidence in the federal government, Bill Clinton, a “New Democrat,” responded by adopting many of the administrative reform proposals that were part of the “reinventing government” movement. This movement ultimately influenced a practice known as the LEAN government initiative. In 2015, Governor Gina Raimondo (D-RI) issued an executive order adopting LEAN across Rhode Island state government. This paper provides an overview of administrative reforms and the reinventing government movement as precursors to the current LEAN government initiatives. From here I will answer: What explains the translation of these past policies into adoption of LEAN in Rhode Island? I hypothesize that this could be explained through theories of policy diffusion. Not only do I discover what led to LEAN in Rhode Island, but I demonstrate how LEAN may affect Rhode Island politics and public policymaking in the future
Psycholinguistics Applied to Reading Instruction
Teachers who are doing their homework in the way of professional reading are meeting with increased frequency the word, psycholinguistics, especially as it relates to reading. One might assume that the very appearance of the word connotes some abstract body of knowledge having meaning only to language theoreticians. On the other hand it is possible that once understood, the word may be a label for a developing body of knowledge that has far-reaching implications for reading teachers. In fact, one might discover that for the most part psycholinguistic thinking puts into a new context much that has been accepted and applied by reading teachers
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