628 research outputs found
Winners and Losers: Formula versus Competitive Funding of Agricultural Research
Research and Development/Tech Change/Emerging Technologies, O3, O4, Q16,
Red and Blue Shifted Broad Lines in Luminous Quasars
We have observed a sample of 22 luminous quasars, in the range 2.0<z<2.5, at
1.6 microns with the near-infrared (NIR) spectrograph FSPEC on the Multiple
Mirror Telescope. Our sample contains 13 radio-loud and 9 radio-quiet objects.
We have measured the systemic redshifts z_(sys) directly from the strong [O
III]5007 line emitted from the narrow-line-region. From the same spectra, we
have found that the non-resonance broad H lines have a systematic mean
redward shift of 520+/-80 km/s with respect to systemic. Such a shift was not
found in our identical analysis of the low-redshift sample of Boroson & Green.
The amplitude of this redshift is comparable to half the expected gravitational
redshift and transverse Doppler effects, and is consistent with a correlation
between redshift differences and quasar luminosity. From data in the
literature, we confirm that the high-ionization rest-frame ultraviolet broad
lines are blueshifted ~550-1050 km/s from systemic, and that these velocity
shifts systematically increase with ionization potential. Our results allow us
to quantify the known bias in estimating the ionizing flux from the
inter-galactic-medium J_(IGM) via the Proximity Effect. Using redshift
measurements commonly determined from strong broad line species, like Ly\alpha
or CIV1549, results in an over-estimation of J_(IGM) by factors of ~1.9-2.3.
Similarly, corresponding lower limits on the density of baryon Omega_b will be
over-estimated by factors of ~1.4-1.5. However, the low-ionization MgII2798
broad line is within ~50 km/s of systemic, and thus would be the line of choice
for determining the true redshift of 1.0<z<2.2 quasars without NIR
spectroscopy, and z>3.1 objects using NIR spectroscopy.Comment: 12 pages, Latex, 2 figures, 2 tables, Accepted for publication in ApJ
Letter
Hard X-ray emitting Active Galactic Nuclei selected by the Chandra Multi-wavelength Project
We present X-ray and optical analysis of 188 AGN identified from 497 hard
X-ray (f (2.0-8.0 keV) > 2.7x10^-15 erg cm^-2 s^-1) sources in 20 Chandra
fields (1.5 deg^2) forming part of the Chandra Multi-wavelength Project. These
medium depth X-ray observations enable us to detect a representative subset of
those sources responsible for the bulk of the 2-8 keV Cosmic X-ray Background.
Brighter than our optical spectroscopic limit, we achieve a reasonable degree
of completeness (77% of X-ray sources with counter-parts r'< 22.5 have been
classified): broad emission line AGN (62%), narrow emission line galaxies
(24%), absorption line galaxies (7%), stars (5%) or clusters (2%). We find that
most X-ray unabsorbed AGN (NH<10^22 cm^-2) have optical properties
characterized by broad emission lines and blue colors, similiar to
optically-selected quasars from the Sloan Digital Sky Survey but with a slighly
broader color distribution. However, we also find a significant population of
redder (g'-i'>1.0) AGN with broad optical emission lines. Most of the X-ray
absorbed AGN (10^22<NH<10^24 cm^-2) are associated with narrow emission line
galaxies, with red optical colors characteristically dominated by luminous,
early type galaxy hosts rather than from dust reddening of an AGN. We also find
a number of atypical AGN; for instance, several luminous AGN show both strong
X-ray absorption (NH>10^22 cm^-2) and broad emission lines. Overall, we find
that 81% of X-ray selected AGN can be easily interpreted in the context of
current AGN unification models. Most of the deviations seem to be due to an
optical contribution from the host galaxies of the low luminosity AGN.Comment: 26 pages; 13 figures (7 color); accepted for publication in the
Astrophysical Journa
Occurrence and Global Properties of Narrow CIV lambda 1549 Absorption Lines in Moderate-Redshift Quasars
A statistical study is presented of (a) the frequency of narrow CIV lambda
1549 absorption lines in 1.5 <~ z <~ 3.6 radio-quiet and radio-loud quasars,
and of (b) the UV and radio properties of the absorbed quasars. The quasar
sample is unbiased with respect to absorption properties and the radio-quiet
and radio-loud subsamples are well matched in redshift and luminosity. A
similarly high incidence (>~50%) of narrow CIV absorbers is detected for the
radio-quiet and radio-loud quasars, and a constant ~25% of all the quasars,
irrespective of radio type display associated CIV absorbers stronger than a
rest equivalent width of 0.5A. Both radio-quiet and radio-loud quasars with
narrow absorption lines have systematically redder continua, especially
strongly absorbed objects. There is evidence of inclination dependent dust
reddening and absorption for the radio quasars. An additional key result is
that the most strongly absorbed radio quasars have the largest radio source
extent. This result is in stark contrast to a recent study of the low-frequency
selected Molonglo survey in which a connection between the strength of the
narrow absorbers and the (young) age of the radio source has been proposed. The
possible origin of these discrepant results is discussed and may be related to
the higher source luminosity for the quasars studied here.Comment: 28 pages, including 10 figures and 8 tables. To appear in ApJ, 599,
December 200
An Orientation Program for Vertical Transfers in Engineering and Engineering Technology
This paper reports on a scholarship program funded by the National Science Foundation that focuses on students who transfer at the 3rd -year level from 2-year schools to the engineering and engineering technology BS programs at our university. The objectives of the program are to: (i) expand and diversify the engineering/technology workforce of the future, (ii) develop linkages and articulations with 2-year schools and their S-STEM (Scholarships in Science, Technology, Engineering and Mathematics) programs, (iii) provide increased career opportunities and job placement rates through mandatory paid co-op experiences, and (iv) serve as a model for other universities to provide vertical transfer students access to the baccalaureate degree. The program is in its third year. It recruited its first group of 25 students in Fall 2017, and another group of 27 students in Fall 2018. We hope to recruit 26 more students in Fall 2019 for a total of 78 vertical transfers. The goal is to retain and graduate at least 95% of these scholars. To enhance the success of these scholars, a zero-credit six-week orientation course was developed in Fall 2017 focusing on four dimensions of student wellness: academic, financial, social, and personal. This paper describes the development of this course, its content, and the modifications that were made to the course for Fall 2018. The paper will also address the research conducted in order to generate knowledge about the program elements that will be essential for the success of vertical transfer programs at other universities. Two research instruments are described: an online survey and a focus group interview that were developed, and administered to the transfer scholars in their first year. Initial findings concerning studentsâ experiences at their 2-year schools, their reason for transferring, their experience in transferring as well as their initial conceptions of what life at a 4-year institution will be like are presented
Scholarship Programs for Vertical Transfers in Engineering and Engineering Technology
This paper introduces two scholarship projects funded by the National Science Foundation that focus on students who transfer at the 3rd year level from 2-year schools to the engineering and engineering technology BS programs at our university. The objectives of both the projects are: (i) to expand and diversify the engineering/technology workforce of the future, (ii) to develop linkages and articulations with 2-year schools and their S-STEM programs, (iii) to provide increased career opportunities and job placement rates through mandatory paid co-op experiences, and (iv) to serve as a model for other universities to provide vertical transfer students access to the baccalaureate degree. The Transfer Pipeline (TiPi) project awarded 25 new scholarships per year from 2012 to 2014 to a total of 75 engineering and engineering technology transfer students. By the end of Fall 2017, 66 (88%) scholars have graduated, 5 (7%) are in process of completing their degrees, and only 4 (5%) left our university, for a 95% retention rate. The paper describes our successes and challenges. The Vertical Transfer Access to the Baccalaureate (VTAB) project recruited its first group of 25 students in Fall 2017 with the goal of recruiting a total of 78 vertical transfers over the next three years. An additional goal of the VTAB project is to conduct research and generate knowledge about the VTAB project elements that will be essential for the success of vertical transfer programs at other universities. The paper describes the research instruments, and the results from an online survey and a focus group interview of the first cohort of VTAB scholars
Phase One Research Results from a Project on Vertical Transfer Students in Engineering and Engineering Technology
This paper reports on the first phase of research on a scholarship program VTAB (Vertical Transfersâ Access to the Baccalaureate) funded by a five-year grant from the National Science Foundation (NSF) that focuses on students who transfer at the 3rd year level from 2-year schools to the engineering and engineering technology BS programs at our university. The goals of the program are: (i) to expand and diversify the engineering/technology workforce of the future, (ii) to develop linkages and articulations with 2-year schools and their S-STEM programs, (iii) to recruit, retain, and graduate 78 low-income students, and place them in industry or graduate schools, (iv) to generate knowledge about the program elements that can help other universities, and (v) to serve as a model for other universities to provide vertical transfer students access to the baccalaureate degree
Application of latent semantic analysis for open-ended responses in a large, epidemiologic study
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