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Radon-222 is a naturally occurring radioactive gas that is responsible for approximately half of the human annual background radiation exposure globally. Chronic exposure to radon and its decay products is estimated to be the second leading cause of lung cancer behind smoking, and links to other forms of neoplasms have been postulated. Ionizing radiation emitted during the radioactive decay of radon and its progeny can induce a variety of cytogenetic effects that can be biologically damaging and result in an increased risk of carcinogenesis. Suggested effects produced as a result of alpha particle exposure from radon include mutations, chromosome aberrations, generation of reactive oxygen species, modification of the cell cycle, up or down regulation of cytokines and the increased production of proteins associated with cell-cycle regulation and carcinogenesis. A number of potential biomarkers of exposure, including translocations at codon 249 of TP53 in addition to HPRT mutations, have been suggested although, in conclusion, the evidence for such hotspots is insufficient. There is also substantial evidence of bystander effects, which may provide complications when calculating risk estimates as a result of exposure, particularly at low doses where cellular responses often appear to deviate from the linear, no-threshold hypothesis. At low doses, effects may also be dependent on cellular conditions as opposed to dose. The cellular and molecular carcinogenic effects of radon exposure have been observed to be both numerous and complex and the elevated chronic exposure of man may therefore pose a significant public health risk that may extend beyond the association with lung carcinogenesis.

Dedication: In memory of Rodica Simion This article is dedicated to the memory of Rodica Simion, one of the greatest enumerators of the 20 th century. Both derangements [8] and restricted permutations [10] were very dear to her heart, and we are sure that she would have appreciated the present surprising connections between these at-first-sight unrelated concepts.Abstract. Define S k n (α) to be the set of permutations of {1, 2,...,n} with exactly k fixed points which avoid the pattern α ∈ S m . Let s k n (α) be the size of S k n (α). We investigate S 0 n (α) for all α ∈ S 3 as well as show that s k n (132) = s k n (213) = s k n (321) and s k n (231) = s k n (312) for all 0 ≤ k ≤ n.

To test installation, one can run the following. 1 import mitiq 2 mitiq . about () Codeblock 2. Testing installation & viewing package versions.This code prints information about the Mitiq version, versions of installed packages, and installation path.