No abstract

This paper describes a high‐accuracy, prototype terrain‐referenced positioning system that uses an airborne laser scanner (ALS) as the terrain sensor. Meter‐level position estimation is performed using a batch processing technique to search for the highest level of agreement between georeferenced ALS data and a digital elevation model (DEM) with approximately 2 m postspacing and elevation accuracy on the order of 30 cm root mean square (RMS). The prototype system uses an ALS with a 33,333 Hz pulse rate, providing a horizontal measurement resolution of less than 5 m. Exhaustive and gradient‐based methods are investigated as part of the batch processing search technique, which calculates the most likely user position within a spatial search area referred to as the sum‐of‐squared‐error (SSE) surface. The performance of the prototype system is evaluated with data collected using the National Aeronautics and Space Administration (NASA) Dryden DC‐8 Airborne Laboratory.

Synaptic activity is intimately linked to neuronal structure and function. Stimulation of live cultured primary neurons, coupled with fluorescent indicator imaging, is a powerful technique to assess the impact of synaptic activity on neuronal protein trafficking and function. Current technology for neuronal stimulation in culture include chemical techniques or microelectrode or optogenetic based techniques. While technically powerful, chemical stimulation has limited spatial resolution and microelectrode and optogenetic techniques require specialized equipment and expertise. We report an optimized and improved technique for laser based photoconductive stimulation of live neurons using an inverted confocal microscope that overcomes these limitations. The advantages of this approach include its non-invasive nature and adaptability to temporal and spatial manipulation. We demonstrate that the technique can be manipulated to achieve spatially selective stimulation of live neurons. Coupled with live imaging of fluorescent indicators, this simple and efficient technique should allow for significant advances in neuronal cell biology.