6,704 research outputs found
Machine Learning with Abstention for Automated Liver Disease Diagnosis
This paper presents a novel approach for detection of liver abnormalities in
an automated manner using ultrasound images. For this purpose, we have
implemented a machine learning model that can not only generate labels (normal
and abnormal) for a given ultrasound image but it can also detect when its
prediction is likely to be incorrect. The proposed model abstains from
generating the label of a test example if it is not confident about its
prediction. Such behavior is commonly practiced by medical doctors who, when
given insufficient information or a difficult case, can chose to carry out
further clinical or diagnostic tests before generating a diagnosis. However,
existing machine learning models are designed in a way to always generate a
label for a given example even when the confidence of their prediction is low.
We have proposed a novel stochastic gradient based solver for the learning with
abstention paradigm and use it to make a practical, state of the art method for
liver disease classification. The proposed method has been benchmarked on a
data set of approximately 100 patients from MINAR, Multan, Pakistan and our
results show that the proposed scheme offers state of the art classification
performance.Comment: Preprint version before submission for publication. complete version
published in proc. 15th International Conference on Frontiers of Information
Technology (FIT 2017), December 18-20, 2017, Islamabad, Pakistan.
http://ieeexplore.ieee.org/document/8261064
Support Vector Machine Classification on a Biased Training Set: Multi-Jet Background Rejection at Hadron Colliders
This paper describes an innovative way to optimize a multivariate classifier,
in particular a Support Vector Machine algorithm, on a problem characterized by
a biased training sample. This is possible thanks to the feedback of a
signal-background template fit performed on a validation sample and included
both in the optimization process and in the input variable selection. The
procedure is applied to a real case of interest at hadron collider experiments:
the reduction and the estimate of the multi-jet background in the
plus jets data sample collected by the CDF experiment. The training samples,
partially derived from data and partially from simulation, are described in
detail together with the input variables exploited for the classification. At
present, the reached performance is superior to any other prescription applied
to the same final state at hadron collider experiments.Comment: 24 pages, 8 figures, preprint of NIM pape
How to Find More Supernovae with Less Work: Object Classification Techniques for Difference Imaging
We present the results of applying new object classification techniques to
difference images in the context of the Nearby Supernova Factory supernova
search. Most current supernova searches subtract reference images from new
images, identify objects in these difference images, and apply simple threshold
cuts on parameters such as statistical significance, shape, and motion to
reject objects such as cosmic rays, asteroids, and subtraction artifacts.
Although most static objects subtract cleanly, even a very low false positive
detection rate can lead to hundreds of non-supernova candidates which must be
vetted by human inspection before triggering additional followup. In comparison
to simple threshold cuts, more sophisticated methods such as Boosted Decision
Trees, Random Forests, and Support Vector Machines provide dramatically better
object discrimination. At the Nearby Supernova Factory, we reduced the number
of non-supernova candidates by a factor of 10 while increasing our supernova
identification efficiency. Methods such as these will be crucial for
maintaining a reasonable false positive rate in the automated transient alert
pipelines of upcoming projects such as PanSTARRS and LSST.Comment: 25 pages; 6 figures; submitted to Ap
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