A high-throughput alpha particle irradiation system for monitoring DNA damage repair, genome instability and screening in human cell and yeast model systems.

Ionizing radiation (IR) is environmentally prevalent and, depending on dose and linear energy transfer (LET), can elicit serious health effects by damaging DNA. Relative to low LET photon radiation (X-rays, gamma rays), higher LET particle radiation produces more disease causing, complex DNA damage that is substantially more challenging to resolve quickly or accurately. Despite the majority of human lifetime IR exposure involving long-term, repetitive, low doses of high LET alpha particles (e.g. radon gas inhalation), technological limitations to deliver alpha particles in the laboratory conveniently, repeatedly, over a prolonged period, in low doses and in an affordable, high-throughput manner have constrained DNA damage and repair research on this topic. To resolve this, we developed an inexpensive, high capacity, 96-well plate-compatible alpha particle irradiator capable of delivering adjustable, low mGy/s particle radiation doses in multiple model systems and on the benchtop of a standard laboratory. The system enables monitoring alpha particle effects on DNA damage repair and signalling, genome stability pathways, oxidative stress, cell cycle phase distribution, cell viability and clonogenic survival using numerous microscopy-based and physical techniques. Most importantly, this method is foundational for high-throughput genetic screening and small molecule testing in mammalian and yeast cells.

Combining skin conductance and forced choice in the detection of concealed information.

An advantage of the concealed information polygraph test (CIT) is that its false positive rate is determined on statistical grounds, and can be set a priori at arbitrary low levels (i.e., few innocents declared guilty). This criterion, however, inevitably leads to a loss of sensitivity (i.e., more guilty suspects declared innocent). We explored whether the sensitivity of a CIT procedure could be increased by adding an independent measure that is based on an entirely different psychological mechanism. In two experiments, we explored whether the accuracy of a CIT procedure could be increased by adding Symptom Validity Testing (SVT), a relatively simple, forced-choice, self-report procedure that has previously been used to detect malingering in various contexts. Results of a feigned amnesia experiment but not from a mock crime experiment showed that a combination measure of both tests yielded better detection than either test alone.