1,584 research outputs found
Crowdsourcing Multiple Choice Science Questions
We present a novel method for obtaining high-quality, domain-targeted
multiple choice questions from crowd workers. Generating these questions can be
difficult without trading away originality, relevance or diversity in the
answer options. Our method addresses these problems by leveraging a large
corpus of domain-specific text and a small set of existing questions. It
produces model suggestions for document selection and answer distractor choice
which aid the human question generation process. With this method we have
assembled SciQ, a dataset of 13.7K multiple choice science exam questions
(Dataset available at http://allenai.org/data.html). We demonstrate that the
method produces in-domain questions by providing an analysis of this new
dataset and by showing that humans cannot distinguish the crowdsourced
questions from original questions. When using SciQ as additional training data
to existing questions, we observe accuracy improvements on real science exams.Comment: accepted for the Workshop on Noisy User-generated Text (W-NUT) 201
Machine-learning techniques can enhance dairy cow estrus detection using location and acceleration data
© 2020 by the authors. Licensee MDPI, Basel, Switzerland. The aim of this study was to assess combining location, acceleration and machine learning technologies to detect estrus in dairy cows. Data were obtained from 12 cows, which were monitored continuously for 12 days. A neck mounted device collected 25,684 records for location and acceleration. Four machine-learning approaches were tested (K-nearest neighbor (KNN), back-propagation neural network (BPNN), linear discriminant analysis (LDA), and classification and regression tree (CART)) to automatically identify cows in estrus from estrus indicators determined by principal component analysis (PCA) of twelve behavioral metrics, which were: duration of standing, duration of lying, duration of walking, duration of feeding, duration of drinking, switching times between activity and lying, steps, displacement, average velocity, walking times, feeding times, and drinking times. The study showed that the neck tag had a static and dynamic positioning accuracy of 0.25 ± 0.06 m and 0.45 ± 0.15 m, respectively. In the 0.5-h, 1-h, and 1.5-h time windows, the machine learning approaches ranged from 73.3 to 99.4% for sensitivity, from 50 to 85.7% for specificity, from 77.8 to 95.8% for precision, from 55.6 to 93.7% for negative predictive value (NPV), from 72.7 to 95.4% for accuracy, and from 78.6 to 97.5% for F1 score. We found that the BPNN algorithm with 0.5-h time window was the best predictor of estrus in dairy cows. Based on these results, the integration of location, acceleration, and machine learning methods can improve dairy cow estrus detection
Thermal disc emission from a rotating black hole: X-ray polarization signatures
Thermal emission from the accretion disc around a black hole can be
polarized, due to Thomson scattering in a disc atmosphere. In Newtonian space,
the polarization angle must be either parallel or perpendicular to the
projection of the disc axis on the sky. As first pointed out by Stark and
Connors in 1977, General Relativity effects strongly modify the polarization
properties of the thermal radiation as observed at infinity. Among these
effects, the rotation of the polarization angle with energy is particularly
useful as a diagnostic tool.
In this paper, we extend the Stark and Connors calculations by including the
spectral hardening factor, several values of the optical depth of the
scattering atmosphere and rendering the results to the expected performances of
planned X-ray polarimeters. In particular, to assess the perspectives for the
next generation of X-ray polarimeters, we consider the expected sensitivity of
the detectors onboard the planned POLARIX and IXO missions. We assume the two
cases of a Schwarzschild and an extreme Kerr black hole with a standard thin
disc and a scattering atmosphere. We compute the expected polarization degree
and the angle as functions of the energy as they could be measured for
different inclinations of the observer, optical thickness of the atmosphere and
different values of the black hole spin. We assume the thermal emission
dominates the X-ray band. Using the flux level of the microquasar GRS 1915+105
in the thermal state, we calculate the observed polarization.Comment: 8 pages, 7 figures, accepted by MNRA
Fast Automatic Vehicle Annotation for Urban Traffic Surveillance
Automatic vehicle detection and annotation for streaming video data with complex scenes is an interesting but challenging task for intelligent transportation systems. In this paper, we present a fast algorithm: detection and annotation for vehicles (DAVE), which effectively combines vehicle detection and attributes annotation into a unified framework. DAVE consists of two convolutional neural networks: a shallow fully convolutional fast vehicle proposal network (FVPN) for extracting all vehicles' positions, and a deep attributes learning network (ALN), which aims to verify each detection candidate and infer each vehicle's pose, color, and type information simultaneously. These two nets are jointly optimized so that abundant latent knowledge learned from the deep empirical ALN can be exploited to guide training the much simpler FVPN. Once the system is trained, DAVE can achieve efficient vehicle detection and attributes annotation for real-world traffic surveillance data, while the FVPN can be independently adopted as a real-time high-performance vehicle detector as well. We evaluate the DAVE on a new self-collected urban traffic surveillance data set and the public PASCAL VOC2007 car and LISA 2010 data sets, with consistent improvements over existing algorithms
When Do Flat Minima Optimizers Work?
Recently, flat-minima optimizers, which seek to find parameters in low-loss neighborhoods, have been shown to improve a neural network's generalization performance over stochastic and adaptive gradient-based optimizers. Two methods have received significant attention due to their scalability: 1. Stochastic Weight Averaging (SWA), and 2. Sharpness-Aware Minimization (SAM). However, there has been limited investigation into their properties and no systematic benchmarking of them across different domains. We fill this gap here by comparing the loss surfaces of the models trained with each method and through broad benchmarking across computer vision, natural language processing, and graph representation learning tasks. We discover several surprising findings from these results, which we hope will help researchers further improve deep learning optimizers, and practitioners identify the right optimizer for their problem
The non-dipolar magnetic fields of accreting T Tauri stars
Models of magnetospheric accretion on to classical T Tauri stars often assume
that stellar magnetic fields are simple dipoles. Recently published surface
magnetograms of BP Tau and V2129 Oph have shown, however, that their fields are
more complex. The magnetic field of V2129 Oph was found to be predominantly
octupolar. For BP Tau the magnetic energy was shared mainly between the dipole
and octupole field components, with the dipole component being almost four
times as strong as that of V2129 Oph. From the published surface maps of the
photospheric magnetic fields we extrapolate the coronal fields of both stars,
and compare the resulting field structures with that of a dipole. We consider
different models where the disc is truncated at, or well-within, the Keplerian
corotation radius. We find that although the structure of the surface magnetic
field is particularly complex for both stars, the geometry of the larger scale
field, along which accretion is occurring, is somewhat simpler. However, the
larger scale field is distorted close to the star by the stronger field
regions, with the net effect being that the fractional open flux through the
stellar surface is less than would be expected with a dipole magnetic field
model. Finally, we estimate the disc truncation radius, assuming that this
occurs where the magnetic torque from the stellar magnetosphere is comparable
to the viscous torque in the disc.Comment: 14 pages, 8 figures. Figures are reduced resolutio
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