Advanced composite aileron for L-1011 transport aircraft: Aileron manufacture

The fabrication activities of the Advanced Composite Aileron (ACA) program are discussed. These activities included detail fabrication, manufacturing development, assembly, repair and quality assurance. Five ship sets of ailerons were manufactured. The detail fabrication effort of ribs, spar and covers was accomplished on male tools to a common cure cycle. Graphite epoxy tape and fabric and syntactic epoxy materials were utilized in the fabrication. The ribs and spar were net cured and required no post cure trim. Material inconsistencies resulted in manufacturing development of the front spar during the production effort. The assembly effort was accomplished in subassembly and assembly fixtures. The manual drilling system utilized a dagger type drill in a hydraulic feed control hand drill. Coupon testing for each detail was done

Direct Measurement of the X-ray Time-Delay Transfer Function in Active Galactic Nuclei

The origin of the observed time lags, in nearby active galactic nuclei (AGN), between hard and soft X-ray photons is investigated using new XMM-Newton data for the narrow-line Seyfert I galaxy Ark 564 and existing data for 1H0707-495 and NGC 4051. These AGN have highly variable X-ray light curves that contain frequent, high peaks of emission. The averaged light curve of the peaks is directly measured from the time series, and it is shown that (i) peaks occur at the same time, within the measurement uncertainties, at all X-ray energies, and (ii) there exists a substantial tail of excess emission at hard X-ray energies, which is delayed with respect to the time of the main peak, and is particularly prominent in Ark 564. Observation (i) rules out that the observed lags are caused by Comptonization time delays and disfavors a simple model of propagating fluctuations on the accretion disk. Observation (ii) is consistent with time lags caused by Compton-scattering reverberation from material a few thousand light-seconds from the primary X-ray source. The power spectral density and the frequency-dependent phase lags of the peak light curves are consistent with those of the full time series. There is evidence for non-stationarity in the Ark 564 time series in both the Fourier and peaks analyses. A sharp `negative' lag (variations at hard photon energies lead soft photon energies) observed in Ark 564 appears to be generated by the shape of the hard-band transfer function and does not arise from soft-band reflection of X-rays. These results reinforce the evidence for the existence of X-ray reverberation in type I AGN, which requires that these AGN are significantly affected by scattering from circumnuclear material a few tens or hundreds of gravitational radii in extent.Comment: Accepted for publication in Ap

Improving accuracy and efficiency of mutual information for multi-modal retinal image registration using adaptive probability density estimation

Mutual information (MI) is a popular similarity measure for performing image registration between different modalities. MI makes a statistical comparison between two images by computing the entropy from the probability distribution of the data. Therefore, to obtain an accurate registration it is important to have an accurate estimation of the true underlying probability distribution. Within the statistics literature, many methods have been proposed for finding the 'optimal' probability density, with the aim of improving the estimation by means of optimal histogram bin size selection. This provokes the common question of how many bins should actually be used when constructing a histogram. There is no definitive answer to this. This question itself has received little attention in the MI literature, and yet this issue is critical to the effectiveness of the algorithm. The purpose of this paper is to highlight this fundamental element of the MI algorithm. We present a comprehensive study that introduces methods from statistics literature and incorporates these for image registration. We demonstrate this work for registration of multi-modal retinal images: colour fundus photographs and scanning laser ophthalmoscope images. The registration of these modalities offers significant enhancement to early glaucoma detection, however traditional registration techniques fail to perform sufficiently well. We find that adaptive probability density estimation heavily impacts on registration accuracy and runtime, improving over traditional binning techniques. © 2013 Elsevier Ltd

Change and Continuity in Student Achievement from Grades 3 to 5: A Policy Dilemma

In this article, we examine student performance on mandated tests in grades 3, 4, and 5 in one state. We focus on this interval, which we term "the fourth grade window," based on our hypothesis that students in grade four are particularly vulnerable to decrements in achievement. The national focus on the third grade as the critical benchmark in student performance has distracted researchers and policy makers from recognition that the fourth grade transition is essential to our understanding of how to promote complex thinking and reasoning that are built upon a foundation of basic skills that may be necessary, but are not sufficient, for the more nuanced learning expected in subsequent grades. We hypothesized that the basic skills that define a successful third grade performance do not predict successful performance in subsequent years. We examined student performance over time using two measures of student success: the Arizona Instrument to Measure Standards (AIMS), a standards based test; and the Stanford 9 (SAT9), a norm-referenced test. Three groups of schools were included in these analyses. Schools were individually matched to the original sample of interest, which were schools serving students of poverty that received state funding to implement Comprehensive School Reform (CSR) models that emphasize continuity across grade levels. The first comparison sample includes schools that also serve students of poverty but did not receive CSR funding, "nonCSR" schools. The second comparison sample includes schools individually matched on all variables except economic status. These schools, which we term "ow poverty" schools, are the wealthiest public schools in the state, with less than 10% of attending students receiving free or reduced lunch. Student test scores in math, reading, and writing (AIMS) or language (SAT9) were analyzed for the years 2000-2003. These intervals allowed the analysis of two cohorts of the fourth grade window. Our results suggest that the reliance on third grade performance to label students and schools is untenable

Sensitivity of the ocean state to the vertical distribution of internal-tide-driven mixing

Author Posting. © American Meteorological Society, 2013. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 43 (2013): 602–615, doi:10.1175/JPO-D-12-055.1.The ocean interior stratification and meridional overturning circulation are largely sustained by diapycnal mixing. The breaking of internal tides is a major source of diapycnal mixing. Many recent climate models parameterize internal-tide breaking using the scheme of St. Laurent et al. While this parameterization dynamically accounts for internal-tide generation, the vertical distribution of the resultant mixing is ad hoc, prescribing energy dissipation to decay exponentially above the ocean bottom with a fixed-length scale. Recently, Polzin formulated a dynamically based parameterization, in which the vertical profile of dissipation decays algebraically with a varying decay scale, accounting for variable stratification using Wentzel–Kramers–Brillouin (WKB) stretching. This study compares two simulations using the St. Laurent and Polzin formulations in the Climate Model, version 2G (CM2G), ocean–ice–atmosphere coupled model, with the same formulation for internal-tide energy input. Focusing mainly on the Pacific Ocean, where the deep low-frequency variability is relatively small, the authors show that the ocean state shows modest but robust and significant sensitivity to the vertical profile of internal-tide-driven mixing. Therefore, not only the energy input to the internal tides matters, but also where in the vertical it is dissipated.This work is a component of the Internal- Wave Driven Mixing Climate Process Team funded by the National Science Foundation Grant OCE-0968721 and the National Oceanic and Atmospheric Administration, U.S. Department of Commerce, Award NA08OAR4320752.2013-09-0

Self-Modification of Policy and Utility Function in Rational Agents

Any agent that is part of the environment it interacts with and has versatile actuators (such as arms and fingers), will in principle have the ability to self-modify -- for example by changing its own source code. As we continue to create more and more intelligent agents, chances increase that they will learn about this ability. The question is: will they want to use it? For example, highly intelligent systems may find ways to change their goals to something more easily achievable, thereby `escaping' the control of their designers. In an important paper, Omohundro (2008) argued that goal preservation is a fundamental drive of any intelligent system, since a goal is more likely to be achieved if future versions of the agent strive towards the same goal. In this paper, we formalise this argument in general reinforcement learning, and explore situations where it fails. Our conclusion is that the self-modification possibility is harmless if and only if the value function of the agent anticipates the consequences of self-modifications and use the current utility function when evaluating the future.Comment: Artificial General Intelligence (AGI) 201

Pressure injury prevalence in a private health service : risks and recommendations

A pressure injury point prevalence was conducted by a private healthcare service (PHS) to determine the prevalence of pressure injuries in inpatients and to provide statistics for use in future comparison studies. The survey was conducted as part of the quality improvement programme of the PHS and the survey instrument was a modified version of a widely used existing tool. On the day of the survey, data collectors, working in pairs, performed skin inspections and completed the survey. Data were then collated and analysed. The overall pressure injury prevalence was 28.2% but with the exclusion of stage one injuries, decreased to 9.9%. Multivariate analysis revealed that the main risk factors for pressure injury development were the inability to reposition independently, older age and having a diagnosis of cancer. The major recommendations for practice change included the provision of pressure relieving devices to all patients unable to reposition independently, alteration of the Braden Scale risk score used on admission to identify older patients at risk from 16 to 18 in accordance with published literature and provision of further education to nurses about use of the Braden Scale and of pressure relieving devices. This study has also highlighted the need for further investigation into the reasons for patient non-participation in research and the direct and indirect relationships between surgery and acquisition of pressure injuries.\u