6,807 research outputs found

    Multi-State Models for Panel Data: The msm Package for R

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    Panel data are observations of a continuous-time process at arbitrary times, for example, visits to a hospital to diagnose disease status. Multi-state models for such data are generally based on the Markov assumption. This article reviews the range of Markov models and their extensions which can be fitted to panel-observed data, and their implementation in the msm package for R. Transition intensities may vary between individuals, or with piecewise-constant time-dependent covariates, giving an inhomogeneous Markov model. Hidden Markov models can be used for multi-state processes which are misclassified or observed only through a noisy marker. The package is intended to be straightforward to use, flexible and comprehensively documented. Worked examples are given of the use of msm to model chronic disease progression and screening. Assessment of model fit, and potential future developments of the software, are also discussed.

    Kickin\u27 Sand and Tellin\u27 Lies

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    This document is the script of the two-act play, Kickin’ Sand and Tellin’ Lies, by Jackson B. Miller and Christopher Forrer. The Linfield College Theatre Program presented the world premieres of the play in November 2012 in McMinnville, Oregon and in Pacific City, Oregon. The play was created as part of the Launching through the Surf: The Dory Fleet of Pacific City project, which focuses on the historical and contemporary role of dory fishers and dories in the life of the coastal village of Pacific City, Oregon. Inspired by stories from the project, Kickin’ Sand and Tellin’ Lies is a fictional work. Inquiries concerning the professional or amateur rights to produce Kickin’ Sand and Tellin’ Lies, or any part thereof, should be addressed to Jackson B. Miller ([email protected]) or the Department of Theatre and Communication Arts, Linfield College, 900 SE Baker St., McMinnville, OR 97128 (503-883-2802).https://digitalcommons.linfield.edu/dory_kstl_play/1002/thumbnail.jp

    Sparticles in Motion - getting to the line in compressed scenarios with the Recursive Jigsaw Reconstruction

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    The observation of light super-partners from a supersymmetric extension to the Standard Model is an intensely sought-after experimental outcome, providing an explanation for the stabilization of the electroweak scale and indicating the existence of new particles which could be consistent with dark matter phenomenology. For compressed scenarios, where sparticle spectra mass-splittings are small and decay products carry low momenta, dedicated techniques are required in all searches for supersymmetry. In this paper we suggest an approach for these analyses based on the concept of Recursive Jigsaw Reconstruction, decomposing each event into a basis of complementary observables, for cases where strong initial state radiation has sufficient transverse momentum to elicit the recoil of any final state sparticles. We introduce a collection of kinematic observables which can be used to probe compressed scenarios, in particular exploiting the correlation between missing momentum and that of radiative jets. As an example, we study squark and gluino production, focusing on mass-splittings between parent super-particles and their lightest decay products between 25 and 200 GeV, in hadronic final states where there is an ambiguity in the provenance of reconstructed jets

    Formation of ions and radicals from icy grains in comets

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    Ion and radical formation in comets are thought to occur primarily by photodissociation of gas phase molecules. Experimental evidence and theoretical calculations are presented that show that some of the radical and ions can come directly from ice grains. The experimental evidence suggest that if the frozen molecules on the surface of grains undergo direct dissociation then they may be able to release radicals directly in the gas phase. If the molecules undergo predissociation it is unlikely that they will release radicals in the gas phase since they should be quenched. Calculations of this direct photodissociation mechanism further indicate that even if the parent molecule undergoes direct dissociation, the yield will not be high enough to explain the rays structure in comets unless the radicals are stored in the grains and then released when the grain evaporates. Calculations were also performed to determine the maximum number of ions that can be stored in an icy grain's radius. This number is compared with the ratio of the ion to neutral molecular density. The comparison suggests that some of the ions observed near the nucleus of the comet could have originally been present in the cometary nucleus. It is also pointed out that the presence of these ions in icy grains could lead to radical formation via electron recombination. Finally, an avalanche process was evaluated as another means of producing ions in comets
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