669 research outputs found
An Introduction to Convolutional Neural Networks
The field of machine learning has taken a dramatic twist in recent times,
with the rise of the Artificial Neural Network (ANN). These biologically
inspired computational models are able to far exceed the performance of
previous forms of artificial intelligence in common machine learning tasks. One
of the most impressive forms of ANN architecture is that of the Convolutional
Neural Network (CNN). CNNs are primarily used to solve difficult image-driven
pattern recognition tasks and with their precise yet simple architecture,
offers a simplified method of getting started with ANNs.
This document provides a brief introduction to CNNs, discussing recently
published papers and newly formed techniques in developing these brilliantly
fantastic image recognition models. This introduction assumes you are familiar
with the fundamentals of ANNs and machine learning.Comment: 10 pages, 5 figure
Computer Vision for Carriers: PATRIOT
Deck tracking performed on carriers currently involves a team of sailors
manually identifying aircraft and updating a digital user interface called the
Ouija Board. Improvements to the deck tracking process would result in
increased Sortie Generation Rates, and therefore applying automation is seen as
a critical method to improve deck tracking. However, the requirements on a
carrier ship do not allow for the installation of hardware-based location
sensing technologies like Global Positioning System (GPS) sensors. PATRIOT
(Panoramic Asset Tracking of Real-Time Information for the Ouija Tabletop) is a
research effort and proposed solution to performing deck tracking with passive
sensing and without the need for GPS sensors. PATRIOT is a prototype system
which takes existing camera feeds, calculates aircraft poses, and updates a
virtual Ouija board interface with the current status of the assets. PATRIOT
would allow for faster, more accurate, and less laborious asset tracking for
aircraft, people, and support equipment. PATRIOT is anticipated to benefit the
warfighter by reducing cognitive workload, reducing manning requirements,
collecting data to improve logistics, and enabling an automation gateway for
future efforts to improve efficiency and safety. The authors have developed and
tested algorithms to perform pose estimations of assets in real-time including
OpenPifPaf, High-Resolution Network (HRNet), HigherHRNet (HHRNet), Faster
R-CNN, and in-house developed encoder-decoder network. The software was tested
with synthetic and real-world data and was able to accurately extract the pose
of assets. Fusion, tracking, and real-world generality are planned to be
improved to ensure a successful transition to the fleet.Comment: 8 pages, 18 figures. Published in the Proceedings of the ASNE 2023
Technology, Systems & Ships Symposium. Reproduced with permission from the
American Society of Naval Engineers. Distribution Statement A: Approved for
public release; distribution is unlimited, as submitted under NAVAIR Public
Release Authorization 2023-01
Assurance for Deployed Continual Learning Systems
The future success of the Navy will depend, in part, on artificial
intelligence. In practice, many artificially intelligent algorithms, and in
particular deep learning models, rely on continual learning to maintain
performance in dynamic environments. The software requires adaptation to
maintain its initial level of performance in unseen situations. However, if not
monitored properly, continual learning may lead to several issues including
catastrophic forgetting in which a trained model forgets previously learned
tasks when being retrained on new data. The authors created a new framework for
safely performing continual learning with the goal of pairing this safety
framework with a deep learning computer vision algorithm to allow for safe and
high-performing automatic deck tracking on carriers and amphibious assault
ships. The safety framework includes several features, such as an ensemble of
convolutional neural networks to perform image classification, a manager to
record confidences and determine the best answer from the ensemble, a model of
the environment to predict when the system may fail to meet minimum performance
metrics, a performance monitor to log system and domain performance and check
against requirements, and a retraining component to update the ensemble and
manager to maintain performance. The authors validated the proposed method
using extensive simulation studies based on dynamic image classification. The
authors showed the safety framework could probabilistically detect out of
distribution data. The results also show the framework can detect when the
system is no longer performing safely and can significantly extend the working
envelope of an image classifier.Comment: 8 pages, 11 figures. Published in the Proceedings of the ASNE 2023
Technology, Systems & Ships Symposium. Reproduced with permission from the
American Society of Naval Engineers. Distribution Statement A: Approved for
public release; distribution is unlimited, as submitted under NAVAIR Public
Release Authorization 2023-02
The Gut Microbiota Composition in Dichorionic Triplet Sets Suggests a Role for Host Genetic Factors
peer-reviewedMonozygotic and dizygotic twin studies investigating the relative roles of host genetics and environmental factors in shaping gut microbiota composition have produced conflicting results. In this study, we investigated the gut microbiota composition of a healthy dichorionic triplet set. The dichorionic triplet set contained a pair of monozygotic twins and a fraternal sibling, with similar pre- and post-natal environmental conditions including feeding regime. V4 16S rRNA and rpoB amplicon pyrosequencing was employed to investigate microbiota composition, and the species and strain diversity of the culturable bifidobacterial population was also examined. At month 1, the monozygotic pair shared a similar microbiota distinct to the fraternal sibling. By month 12 however, the profile was more uniform between the three infants. Principal coordinate analysis (PCoA) of the microbiota composition revealed strong clustering of the monozygotic pair at month 1 and a separation of the fraternal infant. At months 2 and 3 the phylogenetic distance between the monozygotic pair and the fraternal sibling has greatly reduced and by month 12 the monozygotic pair no longer clustered separately from the fraternal infant. Pulse field gel electrophoresis (PFGE) analysis of the bifidobacterial population revealed a lack of strain diversity, with identical strains identified in all three infants at month 1 and 12. The microbiota of two antibiotic-treated dichorionic triplet sets was also investigated. Not surprisingly, in both triplet sets early life antibiotic administration appeared to be a major determinant of microbiota composition at month 1, irrespective of zygosity. By month 12, early antibiotic administration appeared to no longer exert such a strong influence on gut microbiota composition. We hypothesize that initially host genetics play a significant role in the composition of an individual’s gut microbiota, unless an antibiotic intervention is given, but by month 12 environmental factors are the major determinant.This study was performed as part of the INFANTMET project (10/RD/Infantmet/MFRC/705) and was funded by the Government of Ireland's Department of Agriculture Fisheries and in part by Alimentary Pharmabiotic Centre. KM is a Teagasc Walsh Fellow. CS, RPR and PWOT are members of The Alimentary Pharmabiotic Centre, which is a Centre for Science and Technology (CSET) funded by the Science Foundation Ireland (SFI), through the Irish Government’s National Development Plan (Grant no. 02/CE/B124 and 07/CE/B1368)
Structure and stereochemistry of the base excision repair glycosylase MutY reveal a mechanism similar to retaining glycosidases.
MutY adenine glycosylases prevent DNA mutations by excising adenine from promutagenic 8-oxo-7,8-dihydroguanine (OG):A mismatches. Here, we describe structural features of the MutY active site bound to an azaribose transition state analog which indicate a catalytic role for Tyr126 and approach of the water nucleophile on the same side as the departing adenine base. The idea that Tyr126 participates in catalysis, recently predicted by modeling calculations, is strongly supported by mutagenesis and by seeing close contact between the hydroxyl group of this residue and the azaribose moiety of the transition state analog. NMR analysis of MutY methanolysis products corroborates a mechanism for adenine removal with retention of stereochemistry. Based on these results, we propose a revised mechanism for MutY that involves two nucleophilic displacement steps akin to the mechanisms accepted for 'retaining' O-glycosidases. This new-for-MutY yet familiar mechanism may also be operative in related base excision repair glycosylases and provides a critical framework for analysis of human MutY (MUTYH) variants associated with inherited colorectal cancer
Coincident Learning for Unsupervised Anomaly Detection
Anomaly detection is an important task for complex systems (e.g., industrial
facilities, manufacturing, large-scale science experiments), where failures in
a sub-system can lead to low yield, faulty products, or even damage to
components. While complex systems often have a wealth of data, labeled
anomalies are typically rare (or even nonexistent) and expensive to acquire.
Unsupervised approaches are therefore common and typically search for anomalies
either by distance or density of examples in the input feature space (or some
associated low-dimensional representation). This paper presents a novel
approach called CoAD, which is specifically designed for multi-modal tasks and
identifies anomalies based on \textit{coincident} behavior across two different
slices of the feature space. We define an \textit{unsupervised} metric,
, out of analogy to the supervised classification
statistic. CoAD uses to train an anomaly detection algorithm on
\textit{unlabeled data}, based on the expectation that anomalous behavior in
one feature slice is coincident with anomalous behavior in the other. The
method is illustrated using a synthetic outlier data set and a MNIST-based
image data set, and is compared to prior state-of-the-art on two real-world
tasks: a metal milling data set and a data set from a particle accelerator
The impact of the supersonic baryon-dark matter velocity difference on the z~20 21cm background
Recently, Tseliakhovich and Hirata (2010) showed that during the cosmic Dark
Ages the baryons were typically moving supersonically with respect to the dark
matter with a spatially variable Mach number. Such supersonic motion may source
shocks that heat the Universe. This motion may also suppress star formation in
the first halos. Even a small amount of coupling of the 21cm signal to this
motion has the potential to vastly enhance the 21cm brightness temperature
fluctuations at 15<z<40 as well as to imprint acoustic oscillations in this
signal. We present estimates for the size of this coupling, which we calibrate
with a suite of cosmological simulations. Our simulations, discussed in detail
in a companion paper, are initialized to self-consistently account for gas
pressure and the dark matter-baryon relative velocity, v_bc (in contrast to
prior simulations). We find that the supersonic velocity difference
dramatically suppresses structure formation at 10-100 comoving kpc scales, it
sources shocks throughout the Universe, and it impacts the accretion of gas
onto the first star-forming minihalos (even for halo masses as large as ~10^7
Msun). However, we find that the v_bc-sourced temperature fluctuations can
contribute only as much as ~10% of the fluctuations in the 21cm signal. We do
find that v_bc could source an O(1) component in the power spectrum of the 21cm
signal via the X-ray (but not ultraviolet) backgrounds produced once the first
stars formed. In a scenario in which ~10^6 Msun minihalos reheated the Universe
via their X-ray backgrounds, we find that the pre-reionization 21cm signal
would be larger than previously anticipated and exhibit significant acoustic
features. We show that structure formation shocks are unable to heat the
Universe sufficiently to erase a strong 21cm absorption trough at z ~ 20 that
is found in most models of the sky-averaged 21cm intensity.Comment: 17 pages, 11 figures, accepted to ApJ; for movies see
http://astro.berkeley.edu/~mmcquinn/firstligh
Expressive and receptive language skills in preschool children from a socially disadvantaged area
Purpose: Evidence suggests that children present with receptive language skills that are equivalent to or more advanced than expressive language skills. This profile holds true for typical and delayed language development. This study aimed to determine if such a profile existed for preschool children from an area of social deprivation and to investigate if particular language skills influence any differences found between expressive and receptive skills. Method: Data from 187 CELF P2 UK assessments conducted on preschool children from two socially disadvantaged areas in a city in southern Ireland. Result: A significant difference was found between Receptive Language Index (RLI) and Expressive Language Index (ELI) scores with Receptive scores found to be lower than Expressive scores. The majority (78.6%) of participants had a lower Receptive Language than Expressive score (RLI ELI), with very few (3.2%) having the same Receptive and Expressive scores (RLI = ELI). Scores for the Concepts and Following Directions (receptive) sub-test were significantly lower than for the other receptive sub tests, while scores for the Expressive Vocabulary sub-test were significantly higher than for the other expressive sub tests. Conclusion: The finding of more advanced expressive than receptive language skills in socially deprived preschool children is previously unreported and clinically relevant for speech-language pathologists in identifying the needs of this population
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