25,777 research outputs found
The role of earth-based observations of asteroids during the next decade
Present reconnaissance studies of asteroids shift ground based programs to more specialized, intensive studies of selected individual bodies and special classes. Two powerful techniques--radar and mid-IR spectroscopy--have yet to be widely applied to asteroids; high priority should be given to: (1) search programs with a large Schmidt telescope (especially for Mars- and Earth-approaching bodies); (2) a moderate resolution visible and near-IR spectrophotometric survey of at least half the asteroids; (3) high resolution spectrophotometry and radiometry of unusual objects; (4) radar studies of representative main belt asteroids; and (5) application of the full complement of astrophysical techniques to objects of high scientific interest and to potential space mission targets. The infrared astronomical satellite also has high potential for contributing to asteroid science
The Two Regime method for optimizing stochastic reaction-diffusion simulations
The computer simulation of stochastic reaction-diffusion processes in biology is often done using either compartment-based (spatially discretized) simulations or molecular-based (Brownian dynamics) approaches. Compartment-based approaches can yield quick and accurate mesoscopic results but lack the level of detail that is characteristic of the more computationally intensive molecular-based models. Often microscopic detail is only required in a small region but currently the best way to achieve this detail is to use a resource intensive model over the whole domain. We introduce the Two Regime Method (TRM) in which a molecular-based algorithm is used in part of the computational domain and a compartment-based approach is used elsewhere in the computational domain. We apply the TRM to two test problems including a model from developmental biology. We thereby show that the TRM is accurate and subsequently may be used to inspect both mesoscopic and microscopic detail of reaction diffusion simulations according to the demands of the modeller
An analysis of the Mariner 4 photography of Mars
Crater analysis of Mariner 4 photography of Mar
Scattered light in the IUE spectra of Epsilon Aurigae
As a result of this work it was found that light scattered from the longer wavelengths constitutes a small but non-negligible, wavelength and time dependent fraction of the measured flux in the far UV. The reality of the UV excess has not been unambigiously ruled out. However, it is noted that there are still uncertainties in the assumed scattering profile. New measurements of the scattering properties of the cross disperser grating are planned in order to verify the results of Mount and Fastie and extend the wavelength coverage into the far wings of the profile. The results of these measurements will no doubt reduce some of these uncertainties. For the present, it is felt that the BCH approach is a significant improvement over the methods heretofore available for the treatment of scattered light in IUE spectra
High temperature glass coatings for superalloys and refractory metals
New glasses are used as protective coatings on metals and alloys susceptible to oxidation at high temperatures in oxidizing atmospheres. Glasses are stable and solid at temperatures up to 1000 deg C, adhere well to metal surfaces, and are usable for metals with broad range of expansion coefficients
Report of the Terrestrial Bodies Science Working Group. Volume 6: The asteroids
Earth-based astronomical observations and laboratory analysis of meteorites provide the only scientific data available on asteroids. These data are summarized and subjects for future investigations are explored. The measurements required for potential missions are discussed and concepts for a multi-asteroid rendezvous mission in the mid-1980's are outlined
Development and evaluation of controlled viscosity coatings for superalloys
Controlled viscosity glass based protective coatings for superalloys for turbine blade application
Diffusion of multiple species with excluded-volume effects
Stochastic models of diffusion with excluded-volume effects are used to model
many biological and physical systems at a discrete level. The average
properties of the population may be described by a continuum model based on
partial differential equations. In this paper we consider multiple interacting
subpopulations/species and study how the inter-species competition emerges at
the population level. Each individual is described as a finite-size hard core
interacting particle undergoing Brownian motion. The link between the discrete
stochastic equations of motion and the continuum model is considered
systematically using the method of matched asymptotic expansions. The system
for two species leads to a nonlinear cross-diffusion system for each
subpopulation, which captures the enhancement of the effective diffusion rate
due to excluded-volume interactions between particles of the same species, and
the diminishment due to particles of the other species. This model can explain
two alternative notions of the diffusion coefficient that are often confounded,
namely collective diffusion and self-diffusion. Simulations of the discrete
system show good agreement with the analytic results
Working the crowd for forensic research: A review of contributor motivation and recruitment strategies used in crowdsourcing and crowdfunding for scientific research
Crowdsourcing and crowdfunding have been successfully used in a range of scientific disciplines and present opportunities for forensic researchers to draw on the power of large numbers of people to contribute to research projects through participation or by providing an alternative source of funding. This review aimed to examine whether contributors to crowd science and crowdfunding for scientific research are motivated to participate or provide financial support by the same factors, and to examine recruitment strategies in an attempt to identify a potential crowd for forensic researchers to approach. There was found to be limited research into crowdfunding for scientific research that addressed the motivations of contributors or recruitment strategies used, and no conclusions could be made. There is a need to overcome low response rates and high attrition over the lifetime of a crowd science project or crowdfunding appeal. It is necessary to target a large number of people who are interested in the subject studied and who want to make a difference in some way and contribute to science. True crime podcast audiences are proposed as they present large numbers of listeners who are interested in forensic science, criminal investigation or law enforcement. These audiences have been targeted for successful fundraising efforts and invitations to participate in crowd activities previously. They should be considered by forensic researchers who are looking to venture into crowdsourcing or crowdfunding for research projects
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