Bioassay Analysis Using R

We describe an add-on package for the language and environment R which allows simultaneous fitting of several non-linear regression models. The focus is on analysis of dose response curves, but the functionality is applicable to arbitrary non-linear regression models. Features of the package is illustrated in examples.

Detecting the Attenuation of Blazar Gamma-ray Emission by Extragalactic Background Light with GLAST

Gamma rays with energy above 10 GeV interact with optical-UV photons resulting in pair production. Therefore, a large sample of high redshift sources of these gamma rays can be used to probe the extragalactic background starlight (EBL) by examining the redshift dependence of the attenuation of the flux above 10 GeV. GLAST, the next generation high-energy gamma-ray telescope, will have the unique capability to detect thousands of gamma-ray blazars to redshifts of at least z=4, with sufficient angular resolution to allow identification of a large fraction of their optical counterparts. By combining established models of the gamma-ray blazar luminosity function, two different calculations of the high energy gamma-ray opacity due to EBL absorption, and the expected GLAST instrument performance to produce simulated fluxes and redshifts for the blazars that GLAST would detect, we demonstrate that these gamma-ray blazars have the potential to be a highly effective probe of the optical-UV EBL.Comment: 15 pages, AASTeX, 3 eps figures, accepted for publication in Ap

Teaching Laboratory Courses Using Distance Learning Technologies

Conducting laboratory activities is essential for teaching and learning in engineering and technology subjects. This article discusses explorations made by a research team to find solutions to enable the distance-learning delivery of laboratory courses on embedded microcontroller technology topics. In addition, this article includes a review of videoconferencing and course management tools, uniquely designed laboratory equipment and supporting curriculum materials, and statistical evidence showing students can learn technical laboratory content in distance-learning environments

STEM in General Education: Does Mathematics Competence Influence Course Selection

Many students enroll in college programs to prepare for their future careers. All are required to complete general studies courses. At one university, technology and STEM courses fulfill a part of the natural science and technology general education requirements. This study uses a survey design to explore why 332 students chose to enroll in a STEM technology course. Results found most enroll because their advisor suggests the course, it meets a general education major requirement, and the course is offered at a convenient time. Fewer enroll in the course because they would like to find out more about STEM fields, be exposed to potential careers, or because of the implicit need to study STEM subjects. Student mathematics skills were analyzed to determine if these skills influenced their choice for selecting this technology STEM course

A new model for magnetoreception

Certain migratory birds can sense the earth's magnetic field. The nature of this process is not yet properly understood. Here we offer a simple explanation according to which birds literally `see' the local magnetic field: Our model relates the well-established radical pair hypothesis to the phenomenon of Haidinger's brush, a capacity to see the polarisation of light. This new picture explains recent surprising experimental data indicating long lifetimes for the radical pair. Moreover there is a clear evolutionary path toward this field sensing mechanism: it is an enhancement of a weak effect that may be present in many species.Comment: 8 pages, 5 figures, version of final published pape

Generalized linear competition: From pass-through to policy

Economic policy and shifts in input market prices often have significant effects on the marginal costs of firms and can prompt strategic responses that make their impact hard to predict. We introduce “generalized linear competition” (GLC), a new model th

Electrostatic Characterization of Lunar Dust Simulants

Lunar dust can jeopardize exploration activities due to its ability to cling to most surfaces. In this paper, we report on our measurements of the electrostatic properties of the lunar soil simulants. Methods have been developed to measure the volume resistivity, dielectric constant, chargeability, and charge decay of lunar soil. While the first two parameters have been measured in the past [Olhoeft 1974], the last two have never been measured directly on the lunar regolith or on any of the Apollo samples. Measurements of the electrical properties of the lunar samples are being performed in an attempt to answer important problems that must be solved for the development of an effective dust mitigation technology, namely, how much charge can accumulate on the dust and how long does the charge remain on surfaces. The measurements will help develop coatings that are compatible with the intrinsic electrostatic properties of the lunar regolith