g., EC50, ED50, LD50, IC50), and d is the slope at the steepest part of the curve, also known as the Hill slope. The model HIF inhibitor may be written to represent an ascending sigmoid curve of the type in Fig. 1 or a descending curve, depending on the sign of d. Specifically, positive d values yield ascending curves while negative values yield descending curves. Eq. (1) represents one of a family of Hill equations that have been used to describe specific non-linear relationships under diverse scenarios, including, but not limited to, quantitative pharmacology (Gesztelyi et

al., 2012), ligand binding (Poitevin and Edelstein, 2013 and Siman et al., 2012), plant growth modeling (Zub, Rambaud, Bethencourt, & Brancourt-Hulmel, 2012), and modeling patterns of urban electricity usage (To, Lai, Lo, Lam, & Chung, 2012). Computer programs have been available since the early 1970s to estimate the parameters of different versions of the Hill equation, most of which are specific to fitting kinetic data (Atkins, 1973, Knack and Rohm, 1977, Leone et al., 2005 and Wieker et

al., 1970). None of these uses Eq. (1) specifically, although commercial software exists that can be made to fit the four-parameter logistic curve in Eq. (1) (e.g., GraphPad Prism, www.graphpad.com; The MiraiBio Group of Depsipeptide price Hitachi Solutions at www.miraibio.com). Eq. (1) can also be fit to data using a computer program written using the open-access language, R, or the Solver Add-in next in Microsoft Excel. In addition, some of these also permit the computation of confidence and prediction bands around the curve. However, the existing tools either require an investment in commercial software, which are also typically opaque to the user

as to the code and algorithms used to generate the results, or require the ability of the user to write computer code in order to accomplish these tasks. A long-term goal of the Call laboratory is to determine the mechanism of action of inhaled anesthetics (IAs), for which Drosophila melanogaster is used as the model system for providing in vivo responses to IAs in the presence of various genetic manipulations. Drosophila represents a good model for working with anesthetics as fruit flies follow the Meyer–Overton rule of anesthetics and display physiological responses to IAs similar to those in humans ( Allada and Nash, 1993 and Tinklenberg et al., 1991). Additionally, flies provide an inexpensive, yet robust model with access to a variety of genetic tools available to answer many scientific questions in vivo. The Call laboratory has recently adapted an apparatus for the quantification of the Drosophila response to IAs ( Dawson, Heidari, Gadagkar, Murray, & Call, 2013). Known as the inebriometer, it was originally designed to quantitatively measure the flies’ response to ethanol vapors ( Weber, 1988).