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Robert C. Moore

Publications and source records attributed to Robert C. Moore.

2 recordsLinked to original sources

Indirectly Supervised English Sentence Break Prediction Using Paragraph Break Probability Estimates

This report explores the use of paragraph break probability estimates to help predict the location of sentence breaks in English natural language text. We show that a sentence break predictor based almost solely on paragraph break probability estimates can achieve high accuracy on this task. This sentence break predictor is trained almost entirely on a large amount of naturally occurring text without sentence break annotations, with only a small amount of annotated data needed to tune two hyperparameters. We also show that even better results can be achieved across in-domain and out-of-domain test data, if paragraph break probability signals are combined with a support vector machine classifier trained on a somewhat larger amount of sentence-break-annotated data. Numerous related issues are addressed along the way.

cs.CL

The Source Regions of Whistlers

We present a new method for identifying the source regions of lightning generated whistlers observed at a fixed location. In addition to the spatial distribution of causative lightning discharges, we calculate the transmission ratio of lightning discharges into ground detectable whistlers as a function of location. Our method relies on the time of the whistlers and the time and source location of spherics from a global lightning database. We apply this method to whistlers recorded at fifteen ground based stations in the AWDANet (Automatic Whistler Detector and Analyzer Network) operating between 2007-2018 and to located lightning strokes from the WWLLN (World Wide Lightning Location Network) database. We present the obtained maps of causative lightning and transmission ratios. Our results show that the source region of whistlers corresponding to each ground station is around the magnetic conjugate point of the respective station. The size of the source region is typically less than 2000 km in radius with a small fraction of sources extending to up to 3500 km. The transmission ratio is maximal at the conjugate point and decreases with increasing distance from it. This conforms to the theory that whistlers detected on the ground propagated in a ducted mode through the plasmasphere and thus the lightning strokes of their causative spherics must cluster around the footprint of the ducts in the other hemisphere. Our method applied resolves the whistler excitation region mystery that resulted from correlation-based analysis methods, concerning the source region of whistlers detected in Dunedin, New Zealand.

physics.space-ph