6,702 research outputs found
The Effects of a Modified Cover, Copy, Compare on Spelling Third Grade Core Words for a Student with Autism
Since cover copy compare CCC has not been widely implemented for students with autism one purpose of this study was to evaluate the effectiveness of modified CCC on spelling third grade core words for an elementary school student with autism ASD This study adds to the literature by having the participant trace the first time she wrote a word using CCC the form on which the student wrote her words was modified so she could not view her previous performance The present case report provides a replication of employing CCC with a student with autism This intervention required the student to trace the spelling word copy it cover it write it from memory then compare the copied word to the original correct model The effectiveness of CCC was assessed using a non-concurrent multiple-baseline across word sets The results indicated that the intervention was successful for teaching spelling words to a single student with autism in a self-contained special education classroom setting The use of a modified CCC with students with autism was discusse
Unusual glitch activity in the RRAT J1819-1458: an exhausted magnetar?
We present an analysis of regular timing observations of the
high-magnetic-field Rotating Radio Transient (RRAT) J18191458 obtained using
the 64-m Parkes and 76-m Lovell radio telescopes over the past five years.
During this time, the RRAT has suffered two significant glitches with
fractional frequency changes of and .
Glitches of this magnitude are a phenomenon displayed by both radio pulsars and
magnetars. However, the behaviour of J18191458 following these glitches is
quite different to that which follows glitches in other neutron stars, since
the glitch activity resulted in a significant long-term net decrease in the
slow-down rate. If such glitches occur every 30 years, the spin-down rate, and
by inference the magnetic dipole moment, will drop to zero on a timescale of a
few thousand years. There are also significant increases in the rate of pulse
detection and in the radio pulse energy immediately following the glitches.Comment: accepted for publication in MNRAS, 7 pages, 7 figures, 1 tabl
Pulsar J1411+2551: A Low Mass New Double Neutron Star System
In this work, we report the discovery and characterization of PSR J1411+2551,
a new binary pulsar discovered in the Arecibo 327 MHz Drift Pulsar Survey. Our
timing observations of the radio pulsar in the system span a period of about
2.5 years. This timing campaign allowed a precise measurement of its spin
period (62.4 ms) and its derivative (9.6 0.7) ; from these, we derive a characteristic age of Gyr and a
surface magnetic field strength of 2.5 G. These numbers
indicate that this pulsar was mildly recycled by accretion of matter from the
progenitor of the companion star. The system has an eccentric ()
2.61 day orbit. This eccentricity allows a highly significant measurement of
the rate of advance of periastron, . Assuming general relativity accurately models the
orbital motion, this implies a total system mass M = . The minimum companion mass is and the maximum
pulsar mass is . The large companion mass and the orbital
eccentricity suggest that PSR J1411+2551 is a double neutron star system; the
lightest known to date including the DNS merger GW 170817. Furthermore, the
relatively low orbital eccentricity and small proper motion limits suggest that
the second supernova had a relatively small associated kick; this and the low
system mass suggest that it was an ultra-stripped supernova.Comment: Accepted for publication in APJ letter
K-Shell Photoabsorption Studies of the Carbon Isonuclear Sequence
K-shell photoabsorption cross sections for the isonuclear C I - C IV ions
have been computed using the R-matrix method. Above the K-shell threshold, the
present results are in good agreement with the independent-particle results of
Reilman & Manson (1979). Below threshold, we also compute the strong 1s -> np
absorption resonances with the inclusion of important spectator Auger
broadening effects. For the lowest 1s -> 2p, 3p resonances, comparisons to
available C II, C III, and C IV experimental results show good agreement in
general for the resonance strengths and positions, but unexplained
discrepancies exist. Our results also provide detailed information on the C I
K-shell photoabsorption cross section including the strong resonance features,
since very limited laboratory experimental data exist. The resultant R-matrix
cross sections are then used to model the Chandra X-ray absorption spectrum of
the blazar Mkn 421
On the dc Magnetization, Spontaneous Vortex State and Specific Heat in the superconducting state of the weakly ferromagnetic superconductor RuSrGdCuO
Magnetic-field changes 0.2 Oe over the scan length in magnetometers that
necessitate sample movement are enough to create artifacts in the dc
magnetization measurements of the weakly ferromagnetic superconductor
RuSrGdCuO (Ru1212) below the superconducting transition
temperature 30 K. The observed features depend on the specific
magnetic-field profile in the sample chamber and this explains the variety of
reported behaviors for this compound below . An experimental procedure
that combines improvement of the magnetic-field homogeneity with very small
scan lengths and leads to artifact-free measurements similar to those on a
stationary sample has been developed. This procedure was used to measure the
mass magnetization of Ru1212 as a function of the applied magnetic field H (-20
Oe H 20 Oe) at and discuss, in conjunction with
resistance and ac susceptibility measurements, the possibility of a spontaneous
vortex state (SVS) for this compound. Although the existence of a SVS can not
be excluded, an alternative interpretation of the results based on the granular
nature of the investigated sample is also possible. Specific-heat measurements
of SrGdRuO (Sr2116), the precursor for the preparation of Ru1212
and thus a possible impurity phase, show that it is unlikely that Sr2116 is
responsible for the specific-heat features observed for Ru1212 at .Comment: 17 pages, 6 figure
Discovery of the Optical Counterparts to Four Energetic Fermi Millisecond Pulsars
In the last few years, over 43 millisecond radio pulsars have been discovered
by targeted searches of unidentified gamma-ray sources found by the Fermi
Gamma-Ray Space Telescope. A large fraction of these millisecond pulsars are in
compact binaries with low-mass companions. These systems often show eclipses of
the pulsar signal and are commonly known as black widows and redbacks because
the pulsar is gradually destroying its companion. In this paper, we report on
the optical discovery of four strongly irradiated millisecond pulsar
companions. All four sources show modulations of their color and luminosity at
the known orbital periods from radio timing. Light curve modelling of our
exploratory data shows that the equilibrium temperature reached on the
companion's dayside with respect to their nightside is consistent with about
10-30% of the available spin-down energy from the pulsar being reprocessed to
increase the companion's dayside temperature. This value compares well with the
range observed in other irradiated pulsar binaries and offers insights about
the energetics of the pulsar wind and the production of gamma-ray emission. In
addition, this provides a simple way of estimating the brightness of irradiated
pulsar companions given the pulsar spin-down luminosity. Our analysis also
suggests that two of the four new irradiated pulsar companions are only
partially filling their Roche lobe. Some of these sources are relatively bright
and represent good targets for spectroscopic follow-up. These measurements
could enable, among other things, mass determination of the neutron stars in
these systems.Comment: 11 pages, 5 tables, 1 figure, 4 online tables. ApJ submitted and
referee
Quantum Hall Fluids on the Haldane Sphere: A Diffusion Monte Carlo Study
A generalized diffusion Monte Carlo method for solving the many-body
Schr\"odinger equation on curved manifolds is introduced and used to perform a
`fixed-phase' simulation of the fractional quantum Hall effect on the Haldane
sphere. This new method is used to study the effect of Landau level mixing on
the energy gap and the relative stability of spin-polarized and
spin-reversed quasielectron excitations.Comment: 13 pages, Revtex + psfig, figures include
Neutrino-nucleus interaction rates at a low-energy beta-beam facility
We compute the neutrino detection rates to be expected at a low-energy
beta-beam facility. We consider various nuclei as neutrino detectors and
compare the case of a small versus large storage ring.Comment: 6 pages, 3 figure
Coral Disease and Health Workshop: Coral Histopathology II
The health and continued existence of coral reef ecosystems are threatened by an increasing array of environmental and anthropogenic impacts. Coral disease is one of the prominent causes of increased mortality among reefs globally, particularly in the Caribbean. Although over 40 different coral diseases and syndromes have been reported
worldwide, only a few etiological agents have been confirmed; most pathogens remain unknown and the dynamics of disease transmission, pathogenicity and mortality are not
understood. Causal relationships have been documented for only a few of the coral diseases, while new syndromes continue to emerge. Extensive field observations by coral
biologists have provided substantial documentation of a plethora of new pathologies, but our understanding, however, has been limited to descriptions of gross lesions with names reflecting these observations (e.g., black band, white band, dark spot). To determine etiology, we must equip coral diseases scientists with basic biomedical knowledge and specialized training in areas such as histology, cell biology and pathology. Only through
combining descriptive science with mechanistic science and employing the synthesis epizootiology provides will we be able to gain insight into causation and become equipped to handle the pending crisis.
One of the critical challenges faced by coral disease researchers is to establish a framework to systematically study coral pathologies drawing from the field of diagnostic
medicine and pathology and using generally accepted nomenclature. This process began in April 2004, with a workshop titled Coral Disease and Health Workshop: Developing Diagnostic Criteria co-convened by the Coral Disease and Health Consortium (CDHC), a working group organized under the auspices of the U.S. Coral Reef Task Force, and the International Registry for Coral Pathology (IRCP). The workshop was hosted by the U.S. Geological Survey, National Wildlife Health Center (NWHC) in Madison, Wisconsin and was focused on gross morphology and disease signs observed in the field. A resounding recommendation from the histopathologists participating in the workshop was the urgent need to develop diagnostic criteria that are suitable to move from gross observations to morphological diagnoses based on evaluation of microscopic anatomy. (PDF contains 92 pages
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