6,442 research outputs found
Efficiency considerations and the allocation of new deal funds: an examination of the public goods explanation of expenditure patterns
The uneven state-level distribution of New Deal spending has been frequently studied and a variety of economic and political models have been developed. In their article, “Does the Distribution of New Deal Spending Reflect an Optimal Provision of Public Goods?,†(Economics Bulletin, Vol. 8, No. 3, 2007. pp 1-5) Bateman and Taylor propose that much of the disparity in state-level New Deal expenditures can be explained if the creation of public goods and the spillover effects are included in economic models. Using the available wealth of data on New Deal programs, expenditures by agencies within the New Deal are examined and correlation statistics provided to test this hypothesis against the 1930 US census population density figures.New Deal, public good, spillover effects, Public Works Administration, PWA, Civil Works Administration, CWA
Possible Observational Criteria for Distinguishing Brown Dwarfs from Planets
The difference in formation process between binary stars and planetary
systems is reflected in their composition as well as their orbital
architecture, particularly orbital eccentricity as a function of orbital
period. It is suggested here that this difference can be used as an
observational criterion to distinguish between brown dwarfs and planets.
Application of the orbital criterion suggests that with three possible
exceptions, all of the recently-discovered substellar companions discovered to
date may be brown dwarfs and not planets. These criterion may be used as a
guide for interpretation of the nature of sub-stellar mass companions to stars
in the future.Comment: LaTeX, 11 pages including 2 figures, accepted for publication in the
Astrophysical Journal Letter
Physical Activity Belief Scales for Diabetes Risk: Development and Psychometric Testing
This article describes the development and psychometric evaluation of behavioral belief, normative belief, and
control belief scales, derived from the theory of planned behavior to predict physical activity intentions of persons at risk for diabetes. In Study 1, belief statements from interviews were categorized, ranked, and evaluated for item construction. Content validity was established by 96. 1 % agreement among a five-member expert panel. In Study 2, items developed from the belief statements were administered to 106 adults at risk for diabetes. Psychometric analyses provided evidence of construct validity and reliability of the three scales. Internal consistency was sufficient (α = .76-.95), and test-retest evaluations indicated scale stability (r = .79-
.91). Factor analyses and confirmatory factor analysis using structural equation modeling provided evidence that the items were appropriately grouped under each construct. Researchers and practitioners can use these measures to assess behavioral, normative, and control beliefs about physical activity among persons at risk for diabetes
Mating failure shapes the patterns of sperm precedence in an insect
Funding: University of St Andrews PhD Apprenticeship (VLB); Laidlaw Scholarship Programme (DB).Estimates of last male sperm precedence (P2) are often used to infer mechanisms of sperm competition, a form of post-copulatory sexual selection. However, high levels of mating failure (i.e. copulations resulting in no offspring) in a population can lead to misinterpretations of sperm competition mechanisms. Through simulations, GarcĂa-González (2004) illustrated how mating failure could cause bimodal distributions of paternity with peaks at P2 = 0 and 1, under a random sperm mixing mechanism. Here, we demonstrate this effect empirically with the seed bug Lygaeus simulans, a species known to exhibit high levels of mating failure (40–60%), using a morphological marker to estimate paternity. Contrary to previous findings in a sister species, we did not find strong evidence for last male sperm precedence. There was a tendency towards last male precedence (P2 = 0.58) but within the expected range for random sperm mixing. Instead, P2 was highly variable, with a bimodal distribution, as predicted by GarcĂa-González (2004). After taking mating failure into account, the strongest driver of paternity outcome was copulation duration. Furthermore, we found evidence that mating failure could partly be a female-associated trait. Some doubly-mated females were more likely to produce no offspring or produce offspring from two different sires than expected by chance. Therefore, some females are more prone to experience mating failure than others, a result that mirrors an earlier result in male L. simulans. Our results confirm that mating failure needs to be considered when interrogating mechanisms of post-copulatory sexual selection.Publisher PDFPeer reviewe
Development and Validation of a Computational Model for Predicting the Behavior of Plumes from Large Solid Rocket Motors
Exhaust plumes from large solid rocket motors fired at ATK's Promontory test site carry particulates to high altitudes and typically produce deposits that fall on regions downwind of the test area. As populations and communities near the test facility grow, ATK has become increasingly concerned about the impact of motor testing on those surrounding communities. To assess the potential impact of motor testing on the community and to identify feasible mitigation strategies, it is essential to have a tool capable of predicting plume behavior downrange of the test stand. A software package, called PlumeTracker, has been developed and validated at ATK for this purpose. The code is a point model that offers a time-dependent, physics-based description of plume transport and precipitation. The code can utilize either measured or forecasted weather data to generate plume predictions. Next-Generation Radar (NEXRAD) data and field observations from twenty-three historical motor test fires at Promontory were collected to test the predictive capability of PlumeTracker. Model predictions for plume trajectories and deposition fields were found to correlate well with the collected dataset
Planetary astronomy
The authors profile the field of astronomy, identify some of the key scientific questions that can be addressed during the decade of the 1990's, and recommend several facilities that are critically important for answering these questions. Scientific opportunities for the 1990' are discussed. Areas discussed include protoplanetary disks, an inventory of the solar system, primitive material in the solar system, the dynamics of planetary atmospheres, planetary rings and ring dynamics, the composition and structure of the atmospheres of giant planets, the volcanoes of IO, and the mineralogy of the Martian surface. Critical technology developments, proposed projects and facilities, and recommendations for research and facilities are discussed
Recommended from our members
Activated Bone Marrow-Derived Macrophages Eradicate Alzheimer's-Related Aβ42 Oligomers and Protect Synapses.
Impaired synaptic integrity and function due to accumulation of amyloid β-protein (Aβ42) oligomers is thought to be a major contributor to cognitive decline in Alzheimer's disease (AD). However, the exact role of Aβ42 oligomers in synaptotoxicity and the ability of peripheral innate immune cells to rescue synapses remain poorly understood due to the metastable nature of oligomers. Here, we utilized photo-induced cross-linking to stabilize pure oligomers and study their effects vs. fibrils on synapses and protection by Aβ-phagocytic macrophages. We found that cortical neurons were more susceptible to Aβ42 oligomers than fibrils, triggering additional neuritic arborization retraction, functional alterations (hyperactivity and spike waveform), and loss of VGluT1- and PSD95-excitatory synapses. Co-culturing neurons with bone marrow-derived macrophages protected synapses against Aβ42 fibrils; moreover, immune activation with glatiramer acetate (GA) conferred further protection against oligomers. Mechanisms involved increased Aβ42 removal by macrophages, amplified by GA stimulation: fibrils were largely cleared through intracellular CD36/EEA1+-early endosomal proteolysis, while oligomers were primarily removed via extracellular/MMP-9 enzymatic degradation. In vivo studies in GA-immunized or CD115+-monocyte-grafted APPSWE/PS1ΔE9-transgenic mice followed by pre- and postsynaptic analyses of entorhinal cortex and hippocampal substructures corroborated our in vitro findings of macrophage-mediated synaptic preservation. Together, our data demonstrate that activated macrophages effectively clear Aβ42 oligomers and rescue VGluT1/PSD95 synapses, providing rationale for harnessing macrophages to treat AD
Sandia Senior Design Collaboration: Vacuum Sensor Design
Sandia National Laboratories has requested a fully mechanical device to close a circuit after launch has occurred and the device enters a vacuum. Intended for applications in rockets and missiles, the device must fit in a 36 degree wedge with a 6.8 inch radius that is 6 inches in height and be ready to bolt onto a rocket. The pressure switch must be prevented from actuating until a launch acceleration ranging from 20 to 27g is detected. The pressure switch must close the circuit after a pressure of 10-1 Torr is reached and before a pressure of 10-6 Torr is reached. The switch must remain closed after the switch is actuated. The pressure switch is required to close a circuit carrying 30 VDC with a 15 ohm load for up to 15 seconds. The switch itself is allowed to have a maximum resistance of 0.2 ohms. The switch must be resettable for Sandia to conduct multiple test runs. Our contact at Sandia expressed interest in 3D printed components. This design detects the launch acceleration by separating a calibrated mass from a magnet. Before the acceleration sensor is tripped, it prevents the pressure switch from actuating. The pressure switch contains a substance which is a liquid at the temperatures and pressures experienced before the vacuum environment is reached and vaporizes in the vacuum environment. The phase change causes an expansion of the fluid container, which is used to move the actuator magnet near a reed switch and close the circuit. Thus, this project applies thermodynamics, system dynamics, numerical methods, material selection, and mechanical component design. A prototype of the design will be built and sent alongside a report to Sandia National Laboratories. Sandia will test the device on a sounding rocket. This project will provide Sandia with one of ten prototype devices to test. The switch provided will be used to detect when the rocket has left the atmosphere and has activated safety measures
MEF2C regulates outflow tract alignment and transcriptional control of Tdgf1
Congenital heart defects are the most common birth defects in
humans, and those that affect the proper alignment of the outflow
tracts and septation of the ventricles are a highly significant cause of
morbidity and mortality in infants. A late differentiating population of
cardiac progenitors, referred to as the anterior second heart field
(AHF), gives rise to the outflow tract and the majority of the right
ventricle and provides an embryological context for understanding
cardiac outflow tract alignment and membranous ventricular septal
defects. However, the transcriptional pathways controlling AHF
development and their roles in congenital heart defects remain
incompletely elucidated. Here, we inactivated the gene encoding the
transcription factor MEF2C in the AHF in mice. Loss of Mef2c function
in the AHF results in a spectrum of outflow tract alignment defects
ranging from overriding aorta to double-outlet right ventricle and
dextro-transposition of the great arteries. We identify Tdgf1, which
encodes a Nodal co-receptor (also known as Cripto), as a direct
transcriptional target of MEF2C in the outflow tract via an AHFrestricted
Tdgf1 enhancer. Importantly, both the MEF2C and TDGF1
genes are associated with congenital heart defects in humans. Thus,
these studies establish a direct transcriptional pathway between the
core cardiac transcription factor MEF2C and the human congenital
heart disease gene TDGF1. Moreover, we found a range of outflow
tract alignment defects resulting from a single genetic lesion,
supporting the idea that AHF-derived outflow tract alignment
defects may constitute an embryological spectrum rather than
distinct anomalies
- …