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Peters, S.

Publications and source records attributed to Peters, S..

11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Evaluating the organophosphate NIMP on a 3D-brain-on-a-chip system

In the early 1940s, organophosphates used in insecticides were discovered to act as chemical nerve agents. The most common nerve agents are: isopropyl methylphosphonofluoridate (sarin), ethyl dimethylphosphoramidocyanidate (tabun), and S-2-diisopropylaminoethyl O-ethyl methylphosphonothioate (VX). These nerve agents are responsible for causing acetylcholinesterase (AChE) inhibition which leads to acetylcholine gathering in the synapses. This accumulation causes hyperactivity in the nervous system which causes seizures, bradycardia, respiratory paralysis, and eventually death. For this study, the effects of a sarin chemical surrogate, 4-nitrophenyl isopropyl methylphosphonate (NIMP), was evaluated along with the pre-treatment, pyridostigmine bromide (PB) on 3D cultures of human neurons placed on the novel multi-electrode array (MEA). Neuronal spiking and bursting activity was monitored throughout the experiment and levels of cytotoxicity were determined using the lactate dehydrogenase (LDH) assay. In addition, in-vivo analysis was performed for comparison.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Measurements of isocenter path characteristics of the gantry rotation axis with a smartphone application

Purpose: For stereotactic radiosurgery, the AAPM Report No. 54 [AAPM Task Group 42 (AAPM, 1995)] requires the overall stability of the isocenter (couch, gantry, and collimator) to be within a 1 mm radius. In reality, a rotating system has no rigid axis and thus no isocenter point which is fixed in space. As a consequence, the isocenter concept is reviewed here. It is the aim to develop a measurement method following the revised definitions. Methods: The mechanical isocenter is defined here by the point which rotates on the shortest path in the room coordinate system. The path is labeled as “isocenter path.” Its center of gravity is assumed to be the mechanical isocenter. Following this definition, an image-based and radiation-free measurement method was developed. Multiple marker pairs in a plane perpendicular to the assumed gantry rotation axis of a linear accelerator are imaged with a smartphone application from several rotation angles. Each marker pair represents an independent measuring system. The room coordinates of the isocenter path and the mechanical isocenter are calculated based on the marker coordinates. The presented measurement method is by this means strictly focused on the mechanical isocenter. Results: The measurement result is available virtually immediately following completion of measurement. When 12 independent measurement systems are evaluated, the standard deviations of the isocenter path points and mechanical isocenter coordinates are 0.02 and 0.002 mm, respectively. Conclusions: The measurement is highly accurate, time efficient, and simple to adapt. It is therefore suitable for regular checks of the mechanical isocenter characteristics of the gantry and collimator rotation axis. When the isocenter path is reproducible and its extent is in the range of the needed geometrical accuracy, it should be taken into account in the planning process. This is especially true for stereotactic treatments and radiosurgery.

60 APPLIED LIFE SCIENCES↗
NASA NTRS2008

A Lunar Surface Operations Simulator

The Lunar Surface Operations Simulator (LSOS) is being developed to support planning and design of space missions to return astronauts to the moon. Vehicles, habitats, dynamic and physical processes and related environment systems are modeled and simulated in LSOS to assist in the visualization and design optimization of systems for lunar surface operations. A parametric analysis tool and a data browser were also implemented to provide an intuitive interface to run multiple simulations and review their results. The simulator and parametric analysis capability are described in this paper.

Nayar, H.↗
NASA NTRS2003

Rover Technology Development and Infusion for the 2009 Mars Science Laboratory Mission

After the 2003 Mars Exploration Rovers (MER) Mission, NASA plans to send a larger, longer life Mobile Science Laboratory (MSL) in 2009. This rover is planned to last 500 days, travel ten kilometers, and demonstrate autonomous capabilities that reduce the number of communication cycles now needed to achieve successful completion of activities on the surface.

spacecraft autonomy planetary robotics technology ↗
NASA NTRS2001

A science-based executive for autonomous planetary vehicles

If requests for scientific observations, rather than specific plans, are uplinked to an autonomous execution system on the vehicle, it would be able to adjust its execution based upon actual performance. Such a science-based executive control system had been developed and demonstrated for the Rocky7 research rover.

robotic vehicle rover autonomy intelligent executi↗
NASA NTRS1999

NASA's Science Rover for MUSES-C

JPL is building an instrumented rover to be carried by the MUSES-C spacecraft to an asteroid to make in-situ scientific observations from the asteroid surface.

rover asteroid↗
NASA NTRS1997

The Rocky 7 Rover: A Mars Sciencecraft Prototype

This paper describes the design and implementation of a small rover for future Mars missions requiring long traverses and rover-based science experiments at the Jet Propulsion Laboratory.

navigation perception science instrument pointing ↗