2,847 research outputs found
Saving Souls and Securing the Socioeconomic Status Quo: A Consideration of Billy Sunday and the Pacific Garden Mission
With these words, professional baseball player-turned-evangelist Billy Sunday placed himself outside the mainstream of middle-class America\u27s growing urban culture. However, as historian Laurence Moore notes, outsiderhood is a characteristic way of inventing one\u27s Americanness. Indeed, as Sunday\u27s fiery blend of evangelism and vaudeville antics reached into the furthest recesses of the nation\u27s religious consciousness, the revivalist found himself at the forefront of the early twentieth century fundamentalist movement. Emerging from his conversion at Chicago\u27s Pacific Garden Mission, Sunday attained the pinnacle of his success between 1908 and 1920. Little interested in developing a comprehensive theology, both Sunday and Pacific Garden Mission came to perceive themselves as metaphorical lighthouses, moral beacons that could lead sinners through the turbulent seas of sin to safe harbor In Jesus Christ. Despite attempting to address social ills through evangelism, the message of Sunday and the Mission tacitly endorsed the socioeconomic status quo by overwhelmingly emphasizing personal spiritual conversion as the sole means of meaningful reform
The Biology of fun: Do birds just want to have a good time?
The intention of this research project was to delve into the ecological study of playfulness and what appears to be fun in a broad range of bird species. (1) Do all birds exhibit playfulness and use fun? And if so, (2) how have these behaviors contributed to their evolutionary success? Past research has already been underway to biological define what constitutes both “fun” and “play” in animal species. In the past the majority of all test subjects have been mammals, however in the past decade (and especially in the past five years) other vertebrate species such as birds are beginning to be observed as well. The research is still in progress but it seems very obvious from studies so far have concluded that various aviary species do in fact exhibit playful behavior and have fun. Recent hypotheses regarding play in birds, how common it is among various species, and what species have yet to be studied were topics covered in the research. In essence a variety of species of birds are already confirmed to exhibit play behaviors and are used primarily to establish social connects, social hierarchies, and hone predatory and other survival skills.https://scholarscompass.vcu.edu/uresposters/1195/thumbnail.jp
Quantifying and mitigating bias in inference on gravitational wave source populations
When using incorrect or inaccurate signal models to perform parameter
estimation on a gravitational wave signal, biased parameter estimates will in
general be obtained. For a single event this bias may be consistent with the
posterior, but when considering a population of events this bias becomes
evident as a sag below the expected diagonal line of the P-P plot showing the
fraction of signals found within a certain significance level versus that
significance level. It would be hoped that recently proposed techniques for
accounting for model uncertainties in parameter estimation would, to some
extent, alleviate this problem. Here we demonstrate that this is indeed the
case. We derive an analytic approximation to the P-P plot obtained when using
an incorrect signal model to perform parameter estimation. This approximation
is valid in the limit of high signal-to-noise ratio and nearly correct waveform
models. We show how the P-P plot changes if a Gaussian process likelihood that
allows for model errors is used to analyse the data. We demonstrate
analytically and using numerical simulations that the bias is always reduced in
this way. These results provide a way to quantify bias in inference on
populations and demonstrate the importance of utilising methods to mitigate
this bias.Comment: 11 pages, 1 figure, to appear in Phys. Rev. D; v2 includes minor
changes for consistency with accepted versio
Testing the "no-hair" property of black holes with X-ray observations of accretion disks
Accretion disks around black holes radiate a significant fraction of the rest
mass of the accreting material in the form of thermal radiation from within a
few gravitational radii of the black hole (). In
addition, the accreting matter may also be illuminated by hard X-rays from the
surrounding plasma which adds fluorescent transition lines to the emission.
This radiation is emitted by matter moving along geodesics in the metric,
therefore the strong Doppler and gravitational redshifts observed in the
emission encode information about the strong gravitational field around the
black hole. In this paper the possibility of using the X-ray emission as a
strong field test of General Relativity is explored by calculating the spectra
for both the transition line and thermal emission from a thin accretion disk in
a series of parametrically deformed Kerr metrics. In addition the possibility
of constraining a number of known black hole spacetimes in alternative theories
of gravity is considered.Comment: 20 pages, 11 figures, accepted for publication in Physical Review
Novel Method for Incorporating Model Uncertainties into Gravitational Wave Parameter Estimates
Posterior distributions on parameters computed from experimental data using
Bayesian techniques are only as accurate as the models used to construct them.
In many applications these models are incomplete, which both reduces the
prospects of detection and leads to a systematic error in the parameter
estimates. In the analysis of data from gravitational wave detectors, for
example, accurate waveform templates can be computed using numerical methods,
but the prohibitive cost of these simulations means this can only be done for a
small handful of parameters. In this work a novel method to fold model
uncertainties into data analysis is proposed; the waveform uncertainty is
analytically marginalised over using with a prior distribution constructed by
using Gaussian process regression to interpolate the waveform difference from a
small training set of accurate templates. The method is well motivated, easy to
implement, and no more computationally expensive than standard techniques. The
new method is shown to perform extremely well when applied to a toy problem.
While we use the application to gravitational wave data analysis to motivate
and illustrate the technique, it can be applied in any context where model
uncertainties exist.Comment: 6 pages, 3 figures, accepted for publication in Physical Review
Letter
Acquisition Challenge: The Importance of Incompressibility in Comparing Learning Curve Models
The Department of Defense (DoD) cost estimating methodology currently employs T. P. Wrights 75-plus-year-old learning curve formula. The goal of this research was to examine alternative learning curve models and determine if a more reliable and valid cost estimation method exists, which could be incorporated within the DoD acquisition environment. This study tested three alternative learning models (the Stanford-B model, DeJong\u27s learning formula, and the S-Curve model) to compare predicted against actual costs for the F-15 A-E jet fighter platform. The results indicate that the S-Curve and DeJong models offer improvement over current estimation techniques, but more importantly and unexpectedly highlight the importance of incompressibility (the amount of a process that is automated) in learning curve estimating
Validation of demographic equilibrium theory against tree-size distributions and biomass density in Amazonia
Predicting the response of forests to climate and land-use change depends on models that can simulate the time-varying distribution of different tree sizes within a forest – so-called forest demography models. A necessary condition for such models to be trustworthy is that they can reproduce the tree-size distributions that are observed within existing forests worldwide. In a previous study, we showed that demographic equilibrium theory (DET) is able to fit tree-diameter distributions for forests across North America, using a single site-specific fitting parameter (μ) which represents the ratio of the rate of mortality to growth for a tree of a reference size. We use a form of DET that assumes tree-size profiles are in a steady state resulting from the balance between a size-independent rate of tree mortality and tree growth rates that vary as a power law of tree size (as measured by either trunk diameter or biomass). In this study, we test DET against ForestPlots data for 124 sites across Amazonia, fitting, using maximum likelihood estimation, to both directly measured trunk diameter data and also biomass estimates derived from published allometric relationships. Again, we find that DET fits the observed tree-size distributions well, with best-fit values of the exponent relating growth rate to tree mass giving a mean of ϕ=0.71 (0.31 for trunk diameter). This finding is broadly consistent with exponents of ϕ=0.75 (ϕ=1/3 for trunk diameter) predicted by metabolic scaling theory (MST) allometry. The fitted ϕ and μ parameters also show a clear relationship that is suggestive of life-history trade-offs. When we fix to the MST value of ϕ=0.75, we find that best-fit values of μ cluster around 0.25 for trunk diameter, which is similar to the best-fit value we found for North America of 0.22. This suggests an as yet unexplained preferred ratio of mortality to growth across forests of very different types and locations
TCR hypervariable regions expressed by T cells that respond to effective tumor vaccines
A major goal of immunotherapy for cancer is the activation of T cell responses against tumor-associated antigens (TAAs). One important strategy for improving antitumor immunity is vaccination with peptide variants of TAAs. Understanding the mechanisms underlying the expansion of T cells that respond to the native tumor antigen is an important step in developing effective peptide-variant vaccines. Using an immunogenic mouse colon cancer model, we compare the binding properties and the TCR genes expressed by T cells elicited by peptide variants that elicit variable antitumor immunity directly ex vivo. The steady-state affinity of the natural tumor antigen for the T cells responding to effective peptide vaccines was higher relative to ineffective peptides, consistent with their improved function. Ex vivo analysis showed that T cells responding to the effective peptides expressed a CDR3β motif, which was also shared by T cells responding to the natural antigen and not those responding to the less effective peptide vaccines. Importantly, these data demonstrate that peptide vaccines can expand T cells that naturally respond to tumor antigens, resulting in more effective antitumor immunity. Future immunotherapies may require similar stringent analysis of the responding T cells to select optimal peptides as vaccine candidates. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00262-012-1217-5) contains supplementary material, which is available to authorized users
An exploratory randomised controlled trial of a premises-level intervention to reduce alcohol-related harm including violence in the United Kingdom
<b>Background</b><p></p>
To assess the feasibility of a randomised controlled trial of a licensed premises intervention to reduce severe intoxication and disorder; to establish effect sizes and identify appropriate approaches to the development and maintenance of a rigorous research design and intervention implementation.<p></p>
<b>Methods</b><p></p>
An exploratory two-armed parallel randomised controlled trial with a nested process evaluation. An audit of risk factors and a tailored action plan for high risk premises, with three month follow up audit and feedback. Thirty-two premises that had experienced at least one assault in the year prior to the intervention were recruited, match paired and randomly allocated to control or intervention group. Police violence data and data from a street survey of study premises’ customers, including measures of breath alcohol concentration and surveyor rated customer intoxication, were used to assess effect sizes for a future definitive trial. A nested process evaluation explored implementation barriers and the fidelity of the intervention with key stakeholders and senior staff in intervention premises using semi-structured interviews.<p></p>
<b>Results</b><p></p>
The process evaluation indicated implementation barriers and low fidelity, with a reluctance to implement the intervention and to submit to a formal risk audit. Power calculations suggest the intervention effect on violence and subjective intoxication would be raised to significance with a study size of 517 premises.<p></p>
<b>Conclusions</b><p></p>
It is methodologically feasible to conduct randomised controlled trials where licensed premises are the unit of allocation. However, lack of enthusiasm in senior premises staff indicates the need for intervention enforcement, rather than voluntary agreements, and on-going strategies to promote sustainability
- …