4,336 research outputs found
Common Graphics Library (CGL). Volume 1: LEZ user's guide
Users are introduced to and instructed in the use of the Langley Easy (LEZ) routines of the Common Graphics Library (CGL). The LEZ routines form an application independent graphics package which enables the user community to view data quickly and easily, while providing a means of generating scientific charts conforming to the publication and/or viewgraph process. A distinct advantage for using the LEZ routines is that the underlying graphics package may be replaced or modified without requiring the users to change their application programs. The library is written in ANSI FORTRAN 77, and currently uses a CORE-based underlying graphics package, and is therefore machine independent, providing support for centralized and/or distributed computer systems
Examining Community-Based Research as an Application for Public Health Training
The University of Michigan School of Public Health provided community-based research (CBR) opportunities to masters-level students through week-long field experiences in two communities in Mississippi through interdisciplinary collaboration with Delta State University. This article examines the learning outcomes of those field experiences in the context of CBR and the value that those experiences added to their public health proficiency. Quantitative and qualitative data from post-deployment evaluations were examined to determine strengths and weaknesses of this approach to the public health learning process. Overall, students found this approach to provide a rich context for research, help put a face to the numbers, and broaden their perspective of how research is of value to communities and community organizations
Compensatory effects in the PI3K/PTEN/AKT signaling network following receptor tyrosine kinase inhibition
Overcoming de novo and acquired resistance to anticancer drugs that target signaling networks is a formidable challenge for drug design and effective cancer therapy. Understanding the mechanisms by which this resistance arises may offer a route to addressing the insensitivity of signaling networks to drug intervention and restore the efficacy of anticancer therapy. Extending our recent work identifying PTEN as a key regulator of Herceptin sensitivity, we present an integrated theoretical and experimental approach to study the compensatory mechanisms within the PI3K/PTEN/AKT signaling network that afford resistance to receptor tyrosine kinase (RTK) inhibition by anti-HER2 monoclonal antibodies. In a computational model representing the dynamics of the signaling network, we define a single control parameter that encapsulates the balance of activities of the enzymes involved in the PI3K/PTEN/AKT cycle. By varying this control parameter we are able to demonstrate both distinct dynamic regimes of behavior of the signaling network and the transitions between those regimes. We demonstrate resistance, sensitivity, and suppression of RTK signals by the signaling network. Through model analysis we link the sensitivity-to-resistance transition to specific compensatory mechanisms within the signaling network. We study this transition in detail theoretically by variation of activities of PTEN, PI3K, AKT enzymes, and use the results to inform experiments that perturb the signaling network using combinatorial inhibition of RTK, PTEN, and PI3K enzymes in human ovarian carcinoma cell lines. We find good alignment between theoretical predictions and experimental results. We discuss the application of the results to the challenges of hypersensitivity of the signaling network to RTK signals, suppression of drug resistance, and efficacy of drug combinations in anticancer therapy
Detection of bacterial spores with lanthanide-macrocycle binary complexes
The detection of bacterial spores via dipicolinate-triggered lanthanide luminescence has been improved in terms of detection limit, stability, and susceptibility to interferents by use of lanthanide−macrocycle binary complexes. Specifically, we compared the effectiveness of Sm, Eu, Tb, and Dy complexes with the macrocycle 1,4,7,10-tetraazacyclododecane-1,7-diacetate (DO2A) to the corresponding lanthanide aquo ions. The Ln(DO2A)^+ binary complexes bind dipicolinic acid (DPA), a major constituent of bacterial spores, with greater affinity and demonstrate significant improvement in bacterial spore detection. Of the four luminescent lanthanides studied, the terbium complex exhibits the greatest dipicolinate binding affinity (100-fold greater than Tb^(3+) alone, and 10-fold greater than other Ln(DO2A)^+ complexes) and highest quantum yield. Moreover, the inclusion of DO2A extends the pH range over which Tb−DPA coordination is stable, reduces the interference of calcium ions nearly 5-fold, and mitigates phosphate interference 1000-fold compared to free terbium alone. In addition, detection of Bacillus atrophaeus bacterial spores was improved by the use of Tb(DO2A)^+, yielding a 3-fold increase in the signal-to-noise ratio over Tb^(3+). Out of the eight cases investigated, the Tb(DO2A)^+ binary complex is best for the detection of bacterial spores
A Green Bank Telescope Survey of Large Galactic HII Regions
As part of our ongoing HII Region Discovery Survey (HRDS), we report the
Green Bank Telescope detection of 148 new angularly-large Galactic HII regions
in radio recombination line (RRL) emission. Our targets are located at a
declination greater than -45deg., which corresponds to 266deg. > l > -20deg. at
b = 0deg. All sources were selected from the WISE Catalog of Galactic HII
Regions, and have infrared angular diameters >260''. The Galactic distribution
of these "large" HII regions is similar to that of the previously-known sample
of Galactic HII regions. The large HII region RRL line width and peak line
intensity distributions are skewed toward lower values compared with that of
previous HRDS surveys. We discover 7 sources with extremely narrow RRLs <10
km/s. If half the line width is due to turbulence, these 7 sources have thermal
plasma temperatures <1100 K. These temperatures are lower than any measured for
Galactic HII regions, and the narrow line components may arise instead from
partially ionized zones in the HII region photo-dissociation regions. We
discover G039.515+00.511, one of the most luminous HII regions in the Galaxy.
We also detect the RRL emission from three HII regions with diameters >100 pc,
making them some of the physically largest known HII regions in the Galaxy.
This survey completes the HRDS HII region census in the Northern sky, where we
have discovered 887 HII regions and more than doubled the previously-known
census of Galactic HII regions.Comment: Accepted in ApJ
High-Mass Star Formation in the Outer Scutum-Centaurus Arm
The Outer Scutum-Centaurus (OSC) spiral arm is the most distant molecular
spiral arm in the Milky Way, but until recently little was known about this
structure. Discovered by Dame and Thaddeus (2011), the OSC lies 15 kpc
from the Galactic Center. Due to the Galactic warp, it rises to nearly
4 above the Galactic Plane in the first Galactic quadrant, leaving it
unsampled by most Galactic plane surveys. Here we observe HII region candidates
spatially coincident with the OSC using the Very Large Array to image radio
continuum emission from 65 targets and the Green Bank Telescope to search for
ammonia and water maser emission from 75 targets. This sample, drawn from the
WISE Catalog of Galactic HII Regions, represents every HII region candidate
near the longitude-latitude (l,v) locus of the OSC. Coupled with their
characteristic mid-infrared morphologies, detection of radio continuum emission
strongly suggests that a target is a bona fide HII region. Detections of
associated ammonia or water maser emission allow us to derive a kinematic
distance and determine if the velocity of the region is consistent with that of
the OSC. Nearly 60% of the observed sources were detected in radio continuum,
and over 20% have ammonia or water maser detections. The velocities of these
sources mainly place them beyond the Solar orbit. These very distant high-mass
stars have stellar spectral types as early as O4. We associate high-mass star
formation at 2 new locations with the OSC, increasing the total number of
detected HII regions in the OSC to 12.Comment: 14 pages text and tables + 10 pages supplemental figure
An Error-Components Three-Stage Least-Squares Model of Investment Allocation by Farm Households
This paper is an assessment of patterns of investment by farm households via an econometric model adapted from a land allocation approach of Holt (1999). This analysis will shed light on the importance of different classes of assets to farm household well-being, and show the reaction of farm households to a variety of market, international and government effects.Farm Management,
Low-speed aerodynamic characteristics of a twin-engine general aviation configuration with aft-fuselage-mounted pusher propellers
An investigation was conducted to determine the aerodynamic characteristics of an advanced turboprop aircraft model with aft-pylon-mounted pusher propellers. Tests were conducted through an angle-of-attack range of -8 to 28 degrees, and an angle-of-sideslip range of -20 to 20 degrees at free-stream conditions corresponding to Reynolds numbers of 0.55 to 2.14 x 10 to the 6th power based on mean aerodynamic chord. Test results show that for the unpowered configurations the maximum lift coefficients for the cruise, takeoff, and landing configurations are 1.45, 1.90, and 2.10, respectively. Nacelle installation results in a drag coefficient increase of 0.01. Increasing propeller thrust results in a significant increase in lift for angles of attack above stall and improves the longitudinal stability. The cruise configuration remains longitudinally stable to an angle of attack 5 degrees beyond the stall angle, the takeoff configuration is stable 4 degrees beyond stall angle, and the landing configuration is stable 3 degrees beyond stall angle. The predominant effect of symmetric thrust on the lateral-directional aerodynamic characteristics is in the post-stall region, where additional rudder control is available with power on
Complexity, Tunneling and Geometrical Symmetry
It is demonstrated in the context of the simple one-dimensional example of a
barrier in an infinite well, that highly complex behavior of the time evolution
of a wave function is associated with the almost degeneracy of levels in the
process of tunneling. Degenerate conditions are obtained by shifting the
position of the barrier. The complexity strength depends on the number of
almost degenerate levels which depend on geometrical symmetry. The presence of
complex behavior is studied to establish correlation with spectral degeneracy.Comment: 9 revtex pages, 6 Postscript figures (uuencoded
The three species monomer-monomer model in the reaction-controlled limit
We study the one dimensional three species monomer-monomer reaction model in
the reaction controlled limit using mean-field theory and dynamic Monte Carlo
simulations. The phase diagram consists of a reactive steady state bordered by
three equivalent adsorbing phases where the surface is saturated with one
monomer species. The transitions from the reactive phase are all continuous,
while the transitions between adsorbing phases are first-order. Bicritical
points occur where the reactive phase simultaneously meets two adsorbing
phases. The transitions from the reactive to an adsorbing phase show directed
percolation critical behaviour, while the universal behaviour at the bicritical
points is in the even branching annihilating random walk class. The results are
contrasted and compared to previous results for the adsorption-controlled limit
of the same model.Comment: 12 pages using RevTeX, plus 4 postscript figures. Uses psfig.sty.
accepted to Journal of Physics
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