Blocking Mixed-Level Factorials with SAS

Orthogonal array screening designs for mixed-level or asymmetric factorials have recently become popular. Tables of designs and software for creating these designs are readily available to practitioners. However, confounded block designs for mixed-level factorials are not as popular partly due to the fact that software for creating these designs has not been well publicized. Classical methods for creating confounded-block mixed-level factorials normally described in textbooks utilize modular arithmetic or finite fields. In the recent literature optimal design theory has also been proposed as method for creating these designs. Although no examples are shown in the online documentation, both classical and optimal confounded-block mixed-level factorials can be easily created using SAS data step programming in conjunction with proc plan, proc factex or proc optex. In this article we show examples of creating these designs in SAS, and we compare the properties of designs created by classical methods and optimal design theory

Cytotoxicity of Atriplex confertifolia

The search for cancer treatment continues to be a global effort. As part of this global effort, many natural products have been tested against cancer cell lines, mostly from tropically located plants. This study reports that extracts of Atriplex confertifolia (Torr. and Frem.) S. Watson (Chenopodiaceae), a native North American plant (also known as shadscale or saltbush), has significant bioactivity against human breast cancer cell lines MCF-7, MDA-MB 435, MDA-MB 231, and HeLa cells (cervical cancer cells). The bioactivity of A. confertifolia extracts on these cells lines was compared to an FDA-approved cancer drug (Onxol®) and an industry-standard leukocyte control cell line. Active portions of the extracts were found primarily in the polar fractions of the plant. A dose-response curve of the extracts displayed significant cell death similar to Onxol®. The plant extracts did not significantly inhibit the viability of the leukocyte cell line. In a timed study, over 90% of cell lines MDA-MB 435 and HeLa died after 24 hours. Cell death appears to result from apoptosis

The Tetrad-Pollen Model Fails to Explain the Bias in Mendel's Pea (Pisum sativum) Experiments

For >40 years, geneticists and science historians have appealed to the tetrad-pollen model as an explanation of the bias toward expectation in Mendel's data, albeit without experimental support. Our experiments demonstrate that pollen sampling during self-pollination in pea conforms to the binomial distribution with no evidence of a tetrad-pollen effect

Bioassay of selected fungicides for control of chalkbrood in alfalfa leafcutter bees, Megachile rotundata

Bioassays were carried out to determine the effects of 5 selected fungicides on various developmental parameters on the incidence of chalkbrood in Megachile rotundata. The fungicides were bioassayed by incorporation into the natural provisions of leafcutter bees at the egg stage. Half of the fungicide-treated individuals were challenged with 1 x 106 ascospores of Ascosphaera aggregata 24 h after treatment with fungicide. Addition of spore inoculum increased mortality, but chalkbrood levels remained under 50%. All fungicides tested had no effects on bee mortality of non-challenged larvae at doses ≤ 100 ppm. At 1 000 ppm, increased mortality occurred in the Ascocidin, Rovral and enilconazole treatments. Treatment with Rovral resulted in earlier mortality and a slightly prolonged developmental time. Ascocidin, Benlate and Rovral reduced levels of chalkbrood but were toxic to larvae. Consequently these compounds had no effect on total mortality. Treatment with DFMO resulted in increased levels of chalkbrood. Mean developmental times for dying larvae measured by the time to defecation were increased with Rovral. Treatment with Ascocidin, Benlate, DFMO and Rovral resulted in heavier sporulating cadavers compared with controls. This increase in weight of cadavers may translate to increased spore loads