5,884 research outputs found
Automated 5-year Mortality Prediction using Deep Learning and Radiomics Features from Chest Computed Tomography
We propose new methods for the prediction of 5-year mortality in elderly
individuals using chest computed tomography (CT). The methods consist of a
classifier that performs this prediction using a set of features extracted from
the CT image and segmentation maps of multiple anatomic structures. We explore
two approaches: 1) a unified framework based on deep learning, where features
and classifier are automatically learned in a single optimisation process; and
2) a multi-stage framework based on the design and selection/extraction of
hand-crafted radiomics features, followed by the classifier learning process.
Experimental results, based on a dataset of 48 annotated chest CTs, show that
the deep learning model produces a mean 5-year mortality prediction accuracy of
68.5%, while radiomics produces a mean accuracy that varies between 56% to 66%
(depending on the feature selection/extraction method and classifier). The
successful development of the proposed models has the potential to make a
profound impact in preventive and personalised healthcare.Comment: 9 page
Spectral Energy Distributions for Disk and Halo M--Dwarfs
We have obtained infrared (1 to 2.5 micron) spectroscopy for 42 halo and disk
dwarfs with spectral type M1 to M6.5. These data are compared to synthetic
spectra generated by the latest model atmospheres of Allard & Hauschildt.
Photospheric parameters metallicity, effective temperature and radius are
determined for the sample. We find good agreement between observation and
theory except for known problems due to incomplete molecular data for metal
hydrides and water. The metal-poor M subdwarfs are well matched by the models
as oxide opacity sources are less important in this case. The derived effective
temperatures for the sample range from 3600K to 2600K; at these temperatures
grain formation and extinction are not significant in the photosphere. The
derived metallicities range from solar to one-tenth solar. The radii and
effective temperatures derived agree well with recent models of low mass stars.Comment: 24 pages including 13 figures, 4 Tables; accepted by Ap
FeH Absorption in the Near-Infrared Spectra of Late M and L Dwarfs
We present medium-resolution z-, J-, and H-band spectra of four late-type
dwarfs with spectral types ranging from M8 to L7.5. In an attempt to determine
the origin of numerous weak absorption features throughout their near-infrared
spectra, and motivated by the recent tentative identification of the E 4\Pi- A
^4\Pi system of FeH near 1.6 microns in umbral and cool star spectra, we have
compared the dwarf spectra to a laboratory FeH emission spectrum. We have
identified nearly 100 FeH absorption features in the z-, J-, and H-band spectra
of the dwarfs. In particular, we have identified 34 features which dominate the
appearance of the H-band spectra of the dwarfs and which appear in the
laboratory FeH spectrum. Finally, all of the features are either weaker or
absent in the spectrum of the L7.5 dwarf which is consistent with the weakening
of the known FeH bandheads in the spectra of the latest L dwarfs.Comment: accepted by Ap
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