2,150 research outputs found
Why Beggar Thy Indian Neighbor? The Case for Tribal Primacy in Taxation in Indian Country
This report presents legal, practical, and moral arguments to demonstrate that as a legal and economic matter, Indian tax policy is deeply flawed and must be changed
Sprouty1 regulates reversible quiescence of a self-renewing adult muscle stem cell pool during regeneration.
Satellite cells are skeletal muscle stem cells capable of self-renewal and differentiation after transplantation, but whether they contribute to endogenous muscle fiber repair has been unclear. The transcription factor Pax7 marks satellite cells and is critical for establishing the adult satellite cell pool. By using a lineage tracing approach, we show that after injury, quiescent adult Pax7(+) cells enter the cell cycle; a subpopulation returns to quiescence to replenish the satellite cell compartment, while others contribute to muscle fiber formation. We demonstrate that Sprouty1 (Spry1), a receptor tyrosine kinase signaling inhibitor, is expressed in quiescent Pax7(+) satellite cells in uninjured muscle, downregulated in proliferating myogenic cells after injury, and reinduced as Pax7(+) cells re-enter quiescence. We show that Spry1 is required for the return to quiescence and homeostasis of the satellite cell pool during repair. Our results therefore define a role for Spry1 in adult muscle stem cell biology and tissue repair
Play Your Cards Right: Creating a Library Orientation Game (poster)
A team of four librarians and staff drew upon previous experience with game-based learning to develop an orientation activity for transfer students. Apples to Apples -style cards were created using a free online card generator. The game exposed transfer students to information about the campus library system in a low-key way that allowed players with different knowledge levels to socialize and compete against one another on an equal basis
Apple Slices: A Card-Matching Party Game about the Library
Inspired by the popular party games Apples to Apples and Cards Against Humanity, this is a fun and flexible small group activity developed for use in library orientation sessions
Building the Deck: Creating a Library Card Game for Outreach to Transfer Students (poster)
University librarians and staff drew upon previous experience with game-based learning to develop an orientation activity for transfer students. A card game was selected due to the large number of students expected and lack of computers in the available space. Apples to Apples-style cards were created using a free online card generator. Multiple decks were printed to accommodate up to 150 players. The game exposed transfer students to information about the campus library system in a low-key way that allowed players with different knowledge levels to socialize and compete against one another on an equal basis
An analysis of defect densities found during software inspections
Software inspection is a technical evaluation process for finding and removing defects in requirements, design, code, and tests. Detailed data was collected during the first three years of experience at JPL on 203 inspections. Statistics are discussed for this set of inspections. Included, on a per inspection basis, are averages of: staff time expended, pages covered, major defects found, minor defects found, and inspection team size. Analysis of variance showed a significantly higher density of defects during requirements inspections. It was also observed, that the defect densities found decreased exponentially as the work products approached the coding phase. Increasing the pace of the inspection meeting decreased the density of defects found. This relationship was observed to hold for both major and minor defect densities, although it was more pronounced for minor defects. Guidelines are provided for conducting successful software inspections based upon three years of JPL experience
A new method for obtaining the star formation law in galaxies
We present a new observational method to evaluate the star formation law as
formulated by Schmidt: the power-law expression assumed to relate the rate of
star formation in a volume of space to the local total gas volume density.
Volume densities in the clouds surrounding an OB association are determined
with a simple model which considers atomic hydrogen as a photodissociation
product on cloud surfaces. The photodissociating flux incident on the cloud is
computed from the far-UV luminosity of the OB association and the geometry. We
have applied this "PDR Method" to a sample of star-forming regions in M33 using
VLA 21-cm data for the HI and GALEX imagery in the far-UV. It provides an
estimate of the total volume density of hydrogen (atomic + molecular) in the
gas clouds surrounding the young star cluster. A logarithmic graph of the
cluster UV luminosity versus the surrounding gas density is a direct measure of
the star formation law. However, this plot is severely affected by
observational selection, rendering large areas of the diagram inaccessible to
the data. An ordinary least-squares regression fit therefore gives a strongly
biased result. Its slope primarily reflects the boundary defined when the 21-cm
line becomes optically thick, no longer reliably measuring the HI column
density. We use a maximum-likelihood statistical approach which can deal with
truncated and skewed data, taking into account the large uncertainties in the
derived total gas densities. The exponent we obtain for the Schmidt law in M33
is 1.4 \pm 0.2.Comment: Accepted for publication in Ap
CELLO: A fast algorithm for Covariance Estimation
We present CELLO (Covariance Estimation and Learning through Likelihood Optimization), an algorithm for predicting the covariances of measurements based on any available informative features. This algorithm is intended to improve the accuracy and reliability of on-line state estimation by providing a principled way to extend the conventional fixed-covariance Gaussian measurement model. We show that in experiments, CELLO learns to predict measurement covariances that agree with empirical covariances obtained by manually annotating sensor regimes. We also show that using the learned covariances during filtering provides substantial quantitative improvement to the overall state estimate. © 2013 IEEE.United States. National Aeronautics and Space AdministrationSiemens Corporate ResearchUnited States. Office of Naval Research. Multidisciplinary University Research InitiativeMicro Autonomous Consortium Systems and Technolog
The Photometric Period and Variability of the Cataclysmic Variable V849 Herculis (PG 1633+115)
We report time-resolved photometry of the cataclysmic variable V849 Her, and
measure a period of 0.1414 \pm 0.0030 days (3.394 \pm 0.072 hours). We also
present photometry taken over several weeks in 2010 and 2011, as well as light
curves from 1995 to 2011 by the American Association of Variable Star
Observers. The spectra, absolute magnitude derived from infrared magnitudes,
and variability all suggest that V849 Her is a nova-like variable. The shallow
(0.5-magnitude) low states we observe resemble the erratic low states of the VY
Sculptoris stars, although they may recur quasi-periodically over an average
cycle of 12.462 \pm 0.074 days.Comment: 18 pages, 9 figures, accepted for publication in New Astronom
- …