4,531 research outputs found
Hidden Markov models for the activity profile of terrorist groups
The main focus of this work is on developing models for the activity profile
of a terrorist group, detecting sudden spurts and downfalls in this profile,
and, in general, tracking it over a period of time. Toward this goal, a
-state hidden Markov model (HMM) that captures the latent states underlying
the dynamics of the group and thus its activity profile is developed. The
simplest setting of corresponds to the case where the dynamics are
coarsely quantized as Active and Inactive, respectively. A state estimation
strategy that exploits the underlying HMM structure is then developed for spurt
detection and tracking. This strategy is shown to track even nonpersistent
changes that last only for a short duration at the cost of learning the
underlying model. Case studies with real terrorism data from open-source
databases are provided to illustrate the performance of the proposed
methodology.Comment: Published in at http://dx.doi.org/10.1214/13-AOAS682 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Towards Low-Threshold, Real-Time Solar Neutrino Detectors
We discuss an alternative approach to the detection of solar neutrinos using
a coarsely segmented detector based on inverse-beta decay onto Gd or
Yb. While it is know that similar approaches, already discussed in the
literature, can in principle provide low-threshold, real-time energy
spectroscopy with intrinsic background rejection features, the concepts
presented here make this scheme possible with lower background and current
technology.Comment: 10 pages, 2 figure
Development of a Gd Loaded Liquid Scintillator for Electron Anti-Neutrino Spectroscopy
We report on the development and deployment of 11.3 tons of 0.1% Gd loaded
liquid scintillator used in the Palo Verde reactor neutrino oscillation
experiment. We discuss the chemical composition, properties, and stability of
the scintillator elaborating on the details of the scintillator preparation
crucial for obtaining a good scintillator quality and stability.Comment: 9 pages, 4 figures, submitted to NIM
- …