426 research outputs found
Self-Assessment and Planned Change of Placement and Career Services Center
In the 1990s, college and university career services and placement units face many challenges which may influence their success including (a) increased budgetary constraints, (b) changing student demographics, (c) increased availability of computer technologies, (d) new service delivery models, and (e) changing employer recruitment practices. In an effort to address these issues and examine its role within the university (Roth, 1994), the Placement and Career Information Center (PCIC) at Central Michigan University undertook a program of applied research, self-assessment and planned change. The purpose of this article is to briefly report our experiences in conducting this program of applied research. The assessment strategy is presented in the first part of this report. Next, the methods used to collect data and assessment, sampling procedures and response rates are described. Following this, highlights of the assessment results are presented including a summary of some changes already made and those planned for the future. The results of this study are presented in detail in Adams, et at. (1994)
A maximum-likelihood method for improving faint source flux and color estimates
Flux estimates for faint sources or transients are systematically biased high
because there are far more truly faint sources than bright. Corrections which
account for this effect are presented as a function of signal-to-noise ratio
and the (true) slope of the faint-source number-flux relation. The corrections
depend on the source being originally identified in the image in which it is
being photometered. If a source has been identified in other data, the
corrections are different; a prescription for calculating the corrections is
presented. Implications of these corrections for analyses of surveys are
discussed; the most important is that sources identified at signal-to-noise
ratios of four or less are practically useless.Comment: 9 pp., accepted for publication in PAS
Handwriting and Metacognition: The Relationship Between Self-Reflection and Penmanship
The majority of school-based occupational therapy (OT) referrals are for handwriting. In fact, fine motor and handwriting concerns affecting educational performance make up 80-85% of OT referrals in schools. Occupational therapists use an abundance of interventions for remediating handwriting difficulties, but there is scant evidence of why specific strategies or combinations of strategies are effective.
Cognitive interventions have shown to be successful in the treatment of handwriting. Metacognitive skill, a component of cognition, allows a child to self-monitor and self-reflect on his or her handwriting skills to correct mistakes and generate goals for improvement. Therefore, a child’s ability to self-reflect on handwriting is likely an important factor when strengthening the learning and use of handwriting. Having insight into a child’s reflection of his or her handwriting abilities will also assist occupational therapists in creating an appropriate and effective handwriting intervention. This study aims to contribute to the evidence regarding the development and treatment of handwriting skill in elementary school-aged children.https://scholar.dominican.edu/ug-student-posters/1010/thumbnail.jp
The Correlation Between Galaxy HI Linewidths and K' Luminosities
The relationship between galaxy luminosities and rotation rates is studied
with total luminosities in the K' band. Extinction problems are essentially
eliminated at this band centered at 2.1 micron. A template luminosity-linewidth
relation is derived based on 65 galaxies drawn from two magnitude-limited
cluster samples. The zero-point is determined using 4 galaxies with accurately
known distances. The calibration is applied to give the distance to the Pisces
Cluster (60 Mpc) at a redshift in the CMB frame of 4771 km/s. The resultant
value of the Hubble Constant is 81 km/s/Mpc. The largest sources of uncertainty
arises from the small number of zero-point calibrators at this time at K' and
present application to only one cluster.Comment: 13 pages including 5 figures and 2 tables. Accepted for publication
in Astrophysical Journa
The Motions of Clusters of Galaxies and the Dipoles of the Peculiar Velocity Field
In preceding papers of this series, TF relations for galaxies in 24 clusters
with radial velocities between 1000 and 9200 km/s (SCI sample) were obtained, a
Tully-Fisher (TF) template relation was constructed and mean offsets of each
cluster with respect to the template obtained. Here, an estimate of the
line-of-sight peculiar velocities of the clusters and their associated errors
are given. It is found that cluster peculiar velocities in the Cosmic Microwave
Background reference frame do not exceed 600 k/ms and that their distribution
has a line-of-sight dispersion of 300 k/ms, suggesting a more quiescent cluster
peculiar velocity field than previously reported. When measured in a reference
frame in which the Local Group is at rest, the set of clusters at cz > 3000
km/s exhibits a dipole moment in agreement with that of the CMB, both in
amplitude and apex direction. It is estimated that the bulk flow of a sphere of
6000 km/s radius in the CMB reference frame is between 140 and 320 km/s. These
results are in agreement with those obtained from an independent sample of
field galaxies (Giovanelli et al. 1998; see astro-ph/9807274)Comment: 9 pages, 2 tables, 7 figures, uses AAS LaTex; to appear in A
Biases in Virial Black Hole Masses: An SDSS Perspective
We compile black hole (BH) masses for quasars in the redshift
range included in the Fifth Data Release of the
Sloan Digital Sky Survey (SDSS), using virial BH mass estimators based on the
\hbeta, \MgII, and \CIV emission lines. We find that: (1) within our sample,
the widths of the three lines follow log-normal distributions, with means and
dispersions that do not depend strongly on luminosity or redshift;(2) the
\MgII- and \hbeta-estimated BH masses are consistent with one another; and (3)
the \CIV BH mass estimator may be more severely affected by a disk wind
component than the \MgII and \hbeta estimators, giving a positive bias in mass
correlated with the \CIV-\MgII blueshift. Most SDSS quasars have virial BH
masses in the range . There is a clear upper mass limit of
for active BHs at , decreasing at lower
redshifts. Making the reasonable assumptions that the underlying BH mass
distribution decreases with mass and that the Eddington ratio distribution at
fixed BH mass has non-zero width, we show that the measured virial BH mass
distribution and Eddington ratio distribution are subject to Malmquist bias. A
radio quasar subsample (with ) has mean virial BH
mass larger by dex than the whole sample. A broad absorption line
(BAL) quasar subsample (with ) has identical virial
mass distribution as the nonBAL sample, with no mean offset. (Abridged)Comment: Updated virial mass measurements; improved presentation of the MC
simulation; added new discussion sections; conclusions unchanged. The full
table1 is available at
http://www.astro.princeton.edu/~yshen/BH_mass/datafile1.txt.tar.g
An Unbiased Estimate of the Global Hubble Constant in the Region of Pisces-Perseus
We obtain an unbiased estimate of the global Hubble constant H0 in the volume
of cz<12000km/s in the region of Pisces-Perseus. The Tully-Fisher (TF) relation
is applied to a magnitude limited sample of 441 spirals selected from the
Arecibo 21cm catalog. The photometry data were calibrated with CCD observations
and we achieve 0.13mag for the photometric internal error. We use a maximum
likelihood method for the TF analysis. Monte-Carlo simulations demonstrate that
our method reproduces a given H0 at the 95% confidence level. By applying the
method to our sample galaxies, we obtain the unbiased global Hubble constant
H0=65+-2(+20,-14) km/s/Mpc; the first and the second terms represent the
internal random error and the external errors, respectively. We also find a
good agreement for our H0 with those recently obtained via Cepheid observation,
the TF relation and supernovae. Hubble velocities of the spirals inferred from
our H0 show no significant systematic difference from those given in the Mark
III catalog. The same analysis for H0 is carried out using r-band photometry
data of the Pisces-Perseus region given by Willick et al.(1997). We obtain a
global H0 which is consistent with that obtained from our B-band analysis. A
bulk motion in the Pisces-Perseus region is briefly discussed, based on our
calibration of H0. Our r-band TF analysis supports the notion of a coherent
streaming motion of the Pisces-Perseus ridge with -200km/s with respect to the
CMB, in agreement with most modern studies.Comment: 40 pages, 27 postscript figures, to appear in Ap.J. Figures are
included in the tex
Avoiding selection bias in gravitational wave astronomy
When searching for gravitational waves in the data from ground-based
gravitational wave detectors it is common to use a detection threshold to
reduce the number of background events which are unlikely to be the signals of
interest. However, imposing such a threshold will also discard some real
signals with low amplitude, which can potentially bias any inferences drawn
from the population of detected signals. We show how this selection bias is
naturally avoided by using the full information from the search, considering
both the selected data and our ignorance of the data that are thrown away, and
considering all relevant signal and noise models. This approach produces
unbiased estimates of parameters even in the presence of false alarms and
incomplete data. This can be seen as an extension of previous methods into the
high false rate regime where we are able to show that the quality of parameter
inference can be optimised by lowering thresholds and increasing the false
alarm rate.Comment: 13 pages, 2 figure
Supermassive Black Hole Mass Estimates Using Sloan Digital Sky Survey Quasar Spectra at 0.7 < z < 2
We present MgII-based black hole mass estimates for 27,602 quasars with
rest-frame UV spectra available in the Sloan Digital Sky Survey Data Release
Three. This estimation is possible due to the existence of an empirical
correlation between the radius of the broad line region and the continuum
luminosity at 3000 Angstroms. We regenerate this correlation by applying our
measurement method to UV spectra of low-redshift quasars in the HST/IUE
databases which have corresponding reverberation mapping estimates of the Hbeta
broad line region's radius. Our mass estimation method uses the line dispersion
rather than the full width at half maximum of the low-ionization MgII emission
line. We measure MgII line dispersions for quasars whose spectra have been
reconstructed using the most significant eigenspectra produced through
Principal Component Analysis. We have tested the reliability of using
reconstructed spectra in black hole mass estimation using a Monte Carlo
simulation and by comparing the results from original and reconstructed Data
Release Three spectra. We show that using reconstructed spectra not only makes
bias-free mass estimation possible for quasars with low spectroscopic
signal-to-noise ratio, but also reduces the intrinsic scatter of the
distribution of the black hole masses to lower than 0.15 dex.Comment: 38 Pages, 12 figures, 3 Tables, 1 hyperlink to catalogue data.
Accepted for publication in ApJ
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