11,382 research outputs found
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(How) did attack advertisements increase affordable care act enrollments?
We examine the effects of exposure to negative information in attack advertisements in the context of Affordable Care Act (ACA) and Common Core (CC) education standards and show that they lead to an increase in the ACA enrollments and support of the CC standards. To explain this effect, we rely on the knowledge-gap theory and show that individuals who were exposed to more attack advertisements were also more likely to independently seek information, become more knowledgeable, and consequently support these subjects. In addition to an observational study, to test our hypotheses on the link between exposure to negative information, curiosity, and shifts in knowledge and support levels, we design and conduct a randomized experiment using a sample of 300 unique individuals. Our multi-methods research contributes to marketing literature by documenting a rare occasion in which exposure to attack advertisements leads to increased demand and unveiling the mechanisms through which this effect takes place
Blade planform for a quiet helicopter
The effects of blade planform and tip speed on noise and performance for a Hughes 500 C rotor system were studied. A cursory examination of the effects of such planform shapes as regular, inverse, and no taper on the noise and performance of the rotor was conducted. It was found that a constant width wide chord planform at tower tip speed provided the best performance and lowest noise. The tapered planforms had lower performance figures due to the reduced solidity. However, some noise reductions were achieved
Central limit theorem for exponentially quasi-local statistics of spin models on Cayley graphs
Central limit theorems for linear statistics of lattice random fields
(including spin models) are usually proven under suitable mixing conditions or
quasi-associativity. Many interesting examples of spin models do not satisfy
mixing conditions, and on the other hand, it does not seem easy to show central
limit theorem for local statistics via quasi-associativity. In this work, we
prove general central limit theorems for local statistics and exponentially
quasi-local statistics of spin models on discrete Cayley graphs with polynomial
growth. Further, we supplement these results by proving similar central limit
theorems for random fields on discrete Cayley graphs and taking values in a
countable space but under the stronger assumptions of {\alpha}-mixing (for
local statistics) and exponential {\alpha}-mixing (for exponentially
quasi-local statistics). All our central limit theorems assume a suitable
variance lower bound like many others in the literature. We illustrate our
general central limit theorem with specific examples of lattice spin models and
statistics arising in computational topology, statistical physics and random
networks. Examples of clustering spin models include quasi-associated spin
models with fast decaying covariances like the off-critical Ising model, level
sets of Gaussian random fields with fast decaying covariances like the massive
Gaussian free field and determinantal point processes with fast decaying
kernels. Examples of local statistics include intrinsic volumes, face counts,
component counts of random cubical complexes while exponentially quasi-local
statistics include nearest neighbour distances in spin models and Betti numbers
of sub-critical random cubical complexes.Comment: Minor changes incorporated based on suggestions by referee
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Process Parameters Optimization for Ultrasonically Consolidated Fiber-Reinforced Metal Matrix Composites
As an emerging rapid prototyping technology, Ultrasonic Consolidation (UC) has
been used to successfully fabricate metal matrix composites (MMC). The intent of this
study is to identify the optimum combination of processing parameters, including
oscillation amplitude, welding speed, normal force, operating temperature and fiber
orientation, for manufacture of long fiber-reinforced MMCs. The experiments were
designed using the Taguchi method, and an L25 orthogonal array was utilized to
determine the influences of each parameter. SiC fibers of 0.1mm diameter were
successfully embedded into an Al 3003 metal matrix. Two methods were employed to
characterize the bonding between the fiber and matrix material: optical/electron
microscopy and push-out tests monitored by an acoustic emission (AE) sensor. SEM
images and data from push-out tests were analyzed and optimum combinations of
parameters were achieved.Mechanical Engineerin
Computational screening of magnetocaloric alloys
An exciting development over the past few decades has been the use of
high-throughput computational screening as a means of identifying promising
candidate materials for a variety of structural or functional properties.
Experimentally, it is often found that the highest-performing materials contain
substantial atomic site disorder. These are frequently overlooked in
high-throughput computational searches however, due to difficulties in dealing
with materials that do not possess simple, well-defined crystallographic unit
cells. Here we demonstrate that the screening of magnetocaloric materials with
the help of the density functional theory-based magnetic deformation proxy can
be extended to systems with atomic site disorder. This is accomplished by
thermodynamic averaging of the magnetic deformation for ordered supercells
across a solid solution. We show that the highly non-monotonic magnetocaloric
properties of the disordered solid solutions Mn(CoFe)Ge and
(MnNi)CoGe are successfully captured using this method.Comment: Main text: 8 pages, 6 figures. Supplemental Material: 2 pages, 2
figure
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Multi-Material Ultrasonic Consolidation
Ultrasonic consolidation (UC) is a recently developed direct metal solid freeform
fabrication process. While the process has been well-demonstrated for part fabrication in Al alloy
3003 H18, including with intricate cooling channels, some of the potential strengths of the
process have not been fully exploited. One of them is its flexibility with build materials and the
other is its suitability for fabrication of multi-material and functionally graded material parts with
enhanced functional or mechanical properties. Capitalizing on these capabilities is critical for
broadening the application range and commercial utilization of the process. In the current work,
UC was used to investigate ultrasonic bonding of a broad range of engineering materials, which
included stainless steels, Ni-base alloys, brass, Al alloys, and Al alloy composites. UC multimaterial part fabrication was examined using Al alloy 3003 as the bulk part material and the
above mentioned materials as performance enhancement materials. Studies were focused on
microstructural aspects to evaluate interface characteristics between dissimilar material layers.
The results showed that most of these materials can be successfully bonded to Al alloy 3003 and
vice versa using the ultrasonic consolidation process. Bond formation and interface
characteristics between various material combinations are discussed based on oxide layer
characteristics, material properties, and others.Mechanical Engineerin
Environmental triage decisions during a drought
The Murray Darling Basin Current is currently in drought. There are low water levels in most dams, and increased uncertainty about future rainfall. As a result management of the ecosystems in the basin that depend on river flows involves some hard decisions about what assets to save and what assets to let go. This paper models this triage problem using a stochastic and dynamic programming approach. This model is used to identify how optimal management is affected by hysteretic and irreversible effects of drought on ecosystem assets and uncertainty about future climate.Triage, irreversibility, climate change, Environmental Economics and Policy,
Factor VIIa administration in traumatic brain injury: an AAST-MITC propensity score analysis.
Background:Recombinant factor VIIa (rFVIIa) has been used off-label as an adjunct in the reversal of warfarin therapy and management of hemorrhage after trauma. Only a handful of these reports are rigorous studies, from which results regarding safety and effectiveness have been mixed. There remains no clear consensus as to the role of rFVIIa in traumatic brain injury (TBI). Methods:Eleven level 1 trauma centers provided clinical data and head CT scans of patients with a Glasgow Coma Scale (GCS) score of ≤13 and radiographic evidence of TBI. A propensity score (PS) to receive rFVIIa in those surviving ≥2 days was calculated for each patient based on patient demographics, comorbidities, physiology, Injury Severity Score, admission GCS score, and treatment center. Patients receiving rFVIIa within 24 hours of admission were matched to patients who did not receive rFVIIa for outcomes assessment. Subgroup analysis evaluated patients with primary head injury with PS matching. Results:There were 4284 patient observations; 129 received rFVIIa. Groups were comparable after matching. No differences in mortality or morbidity were found. Improvement in GCS score from admission to discharge was less among those receiving rFVIIa (5.5 vs. 2.4; P value 0.001); however, there was no difference in average GCS score at discharge. No significant differences in outcomes were identified in patients with isolated TBI receiving rFVIIa. Discussion:rFVIIa in early management of TBI is not associated with a decreased risk of mortality or morbidity, and may negatively impact recovery and functional status at discharge in the severely injured patient with polytrauma. Level of evidence:Level III. Study type:Therapeutic/care management
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