An R Implementation of the Polya-Aeppli Distribution

An efficient implementation of the Polya-Aeppli, or geometirc compound Poisson, distribution in the statistical programming language R is presented. The implementation is available as the package polyaAeppli and consists of functions for the mass function, cumulative distribution function, quantile function and random variate generation with those parameters conventionally provided for standard univatiate probability distributions in the stats package in RComment: 9 pages, 2 figure

Review-discussion: historical knowledge and historical narratives in the Severan period: Adam M. Kemezis, Greek Narratives of the Roman Empire under the Severans: Cassius Dio, Philostratus, and Herodian, Greek Culture in the Roman World

No abstract available

Barriers and solutions to innovation in teacher education

This article proposes how mobile technologies are being employed innovatively in teacher education across the European Union, contributing to an adjustment in teacher training models. It identifies various barriers and challenges to innovation and illustrates how teacher educators have addressed these in the first year of an Erasmus+ funded project

Non-perturbative Fermion Propagator for the Massless Quenched QED3

For massless quenched QED in three dimensions, we evaluate a non-perturbative expression for the fermion propagator which agrees with its two loop perturbative expansion in the weak coupling regime. This calculation is carried out by making use of the Landau-Khalatnikov-Fradkin transformations. Any improved construction of the fermion-boson vertex must make sure that the solution of the Schwinger-Dyson equation for the fermion propagator reproduces this result. For two different gauges, we plot the fermion propagator against momentum. We then make a comparison with a similar plot, using the earlier expression for the fermion propagator, which takes into account only the one loop result.Comment: 11 pages, 3 figures, to appear in Phys. Lett.

Parasitoids of \u3ci\u3eChionaspis Pinifoliae\u3c/i\u3e (Homoptera: Diaspididae) in Iowa

Three parasitoids (Hymenoptera: Encyrtidae: Aphelininae), Aphytis diaspidis, Coccobius varicornis, and Marietta pulchella, were recovered from field collections of the pine needle scale, Chionaspis pinifoliae, on Pinus sylvestris in central Iowa. Parasitoid mean time (± SEM) to emergence from overwintered scale mummies occurred at 46.6 (4.6) and 23.9 (1.3) days for C. varicornis and M. pulchella, respectively, using a 16L:8D photoperiod and a corresponding temperature regime of 22°C and 18°C. Growing-season parasitism level on field-collected female C. pinifoliae was 15%; parasitoid community composition was 86% A. diaspidis, 12% C. varicornis, and 2% M. pulchella