4,772 research outputs found
Using Evolutionary Strategies for the Real-Time Learning of Controllers for Autonomous Agents in Xpilot-AI
Real-time learning is the process of an artificial intelligence agent learning behavior(s) at the same pace as it operates in the real world. Video games tend to be an excellent locale for testing real-time learning agents, as the action happens at real speeds with a good visual feedback mechanism, coupled with the possibility of comparing human performance to that of the agent\u27s. In addition, players want to be competing against a consistently challenging opponent. This paper is a discussion of a controller for an agent in the space combat game Xpilot and the evolution of said controller using two different methods. The controller is a multilayer neural network, which controls all facets of the agent\u27s behavior that are not created in the initial set-up. The neural network is evolved using 1-to-1 evolutionary strategies in one method and genetic algorithms in the other method. Using three independent trials per methodology, it was shown that evolutionary strategies learned faster, while genetic algorithms learned more consistently, leading to the idea that genetic algorithms may be superior when there is ample time before use, but evolutionary strategies are better when pressed for learning time as in real-time learning
Predictors of Non-use of Intrauterine Contraception among women aged 18-49 years in a General practice setting in the UK
Objectives:
Our research examined the barriers to the uptake of Intrauterine Contraception (IUC) by women in a general practice setting in the UK. This paper reports predictors of non-use of IUC in this context.
Design:
We used a mixed method QUAL/Quant approach in which initial qualitative research provides a framework for subsequent larger quantitative surveys. Utilising findings derived from 30 qualitative interviews, a quantitative survey was developed and distributed to a pragmatic sample of 1195 women, aged 18-49 years, who were recruited through 32 participating GP practices in an area of England, UK. Outcome measures were percentage of attributes or responses in the sample and use or non-use of IUC. Results were analysed using descriptive statistical analysis and binary logistic regression, using Use/Non-Use as a binary response variable.
Results:
Attitudinal variables which were the strongest predictors of non-use of IUC were; an adverse opinion on long acting aspect of IUC (OR=8.34), disliking the thought of IUC inside the body (OR=3.138), concerns about IUC causing difficulties becoming pregnant in the future (OR=2.587), concerns about womb damage (OR=2.224), having heard adverse opinions about levonorgestrel - releasing IUS (Mirena®) (OR= 2.551), having an adverse opinion of having light, irregular periods (OR=2.382) and having an adverse opinion of having no periods (OR=2.018).
Conclusions:
Concerns about the long-acting nature of IUC and persisting concerns about the safety of IUC may act as barriers to its use. Information for women, tailored to specifically address these concerns, is needed
The Masses and Shapes of Dark Matter Halos from Galaxy-Galaxy Lensing in the CFHTLS
We present the first galaxy-galaxy weak lensing results using early data from
the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). These results are
based on ~22 sq. deg. of i' data. From this data, we estimate the average
velocity dispersion for an L* galaxy at a redshift of 0.3 to be 137 +- 11 km/s,
with a virial mass, M_{200}, of 1.1 +- 0.2 \times 10^{12} h^{-1} Msun and a
rest frame R-band mass-to-light ratio of 173 +- 34 h Msun/Lsun. We also
investigate various possible sources of systematic error in detail.
Additionally, we separate our lens sample into two sub-samples, divided by
apparent magnitude, thus average redshift. From this early data we do not
detect significant evolution in galaxy dark matter halo mass-to-light ratios
from a redshift of 0.45 to 0.27. Finally, we test for non-spherical galaxy dark
matter halos. Our results favor a dark matter halo with an ellipticity of ~0.3
at the 2-sigma level when averaged over all galaxies. If the sample of
foreground lens galaxies is selected to favor ellipticals, the mean halo
ellipticity and significance of this result increase.Comment: 12 pages, 11 figures, accepted to ApJ, uses emulateap
A Method For Sorting Bottom Fauna Samples By Elutriation
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109814/1/lno1961640462.pd
Provider-based barriers to provision of intrauterine contraception in general practice
Objectives: Intrauterine contraception (IUC) is highly effective, safe and long-lasting, but is not a popular method of contraception among British women. This study examined barriers to the uptake of IUC in general practice in England.
Method: A sequential mixed-method approach to explore the views of practitioners regarding the provision of IUC. We e-surveyed 208 practitioners from 69 practices in a region of England and subsequently interviewed 14 practitioners from eight practices.
Results: Just under half of general practitioners (GPs) (46.8%; 58/124), and only 8.2% (4/49) of nurses reported being trained to fit IUC. Lack of knowledge of IUC was a barrier to fitting, and also to recommending IUC, especially by practitioners who were not trained to fit. There was discordance between reported knowledge of eligibility for IUC and the likelihood of recommending IUC. Respondents were less likely to recommend IUC to young, nulliparous women, women who had experienced a previous ectopic pregnancy, a recent sexually transmitted infection (STI), or an abnormal cervical smear. The qualitative data indicate that risk aversion and limited training, together with practitioners’ assessments that women are uninterested, may lead to IUC being precluded as a suitable method.
Conclusions: Increased practitioner education, for those not trained to fit IUC, may remove a barrier to the uptake of IUC in general practice. More research is required on the discordance between the practitioners’ views on the characteristics of women considered suitable for IUC, and the criteria set out in the UK Medical Eligibility Criteria (UKMEC) guidelines
Combining Real-Time fMRI Neurofeedback Training of the DLPFC with N-Back Practice Results in Neuroplastic Effects Confined to the Neurofeedback Target Region
In traditional fMRI, individuals respond to exogenous stimuli and are naïve to the effects of the stimuli on their neural activity patterns. Changes arising in the fMRI signal are analyzed post-hoc to elucidate the spatial and temporal activation of brain regions associated with the tasks performed. The advent of real-time fMRI has enabled a new method to systematically alter brain activity across space and time using neurofeedback training (NFT), providing a new tool to study internally-driven processes such as neuroplasticity. In this work, we combined n-back practice with fMRI-NFT of the left dorsolateral prefrontal cortex (DLPFC) to better understand the relationship between open- and closed-loop neuromodulation. FMRI data were acquired during both traditional n-back and NFT across five imaging sessions. Region-of-interest (ROI) and voxel-wise 2 × 2 within subjects ANOVAs were carried out to determine the effects of, and interaction between, training session and neuromodulation type. A main effect of training session was identified for only a single, highly focused cluster that shared spatial properties with the fMRI-NFT target region (left DLPFC). This finding indicates that combined open- and closed-loop neuroplastic enhancement techniques result in focal changes that are confined to the target area of NFT, and do not affect up- or down-stream network components that are normally engaged during working memory. Additionally, we identified a main effect of neuromodulation type for 15 clusters with significantly different activation between open- and closed-loop neuromodulation during training, 12 of which demonstrated higher activity during the open-loop neuromodulation. Our results, taken together with previous reports, indicate that fMRI-NFT combined with n-back practice leads to a highly focal volume exhibiting neuroplasticity without additional network effects
Searching for Faint Planetary Nebulae Using the Digital Sky Survey
Recent Halpha surveys such as SHS and IPHAS have improved the completeness of
the Galactic planetary nebula (PN) census. We now know of ~3,000 PNe in the
Galaxy, but this is far short of most estimates, typically ~25,000 or more for
the total population. The size of the Galactic PN population is required to
derive an accurate estimate of the chemical enrichment rates of nitrogen,
carbon, and helium. In addition, a high PN count (~20,000) is strong evidence
that most 1-8 Msun main sequence stars will go through a PN phase, while a low
count (<10,000) argues that special conditions (e.g., a close binary
interaction) are required to form a PN. We describe a technique for finding
hundreds more PNe using the existing data collections of the digital sky
surveys, thereby improving the census of Galactic PNe.Comment: 11 pages, 7 figures, accepted for publication in the Publications of
the Astronomical Society of Australia (PASA), full resolution paper available
at http://www.wiyn.org/jacoby_pasa.pd
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