104,888 research outputs found
The Role of Economic Factors, Including the Level of Tuition, in Individual University Participation Decisions in Canada
The study uses individual data from the Canadian Labour Force Survey to consider economic factors in university participation decisions by persons aged 17-24 from 1976 to 2003. The level of real tuition is one economic factor that may affect the university participation decision. There is also regional variation in the opportunity cost of university attendance; in the reduction in the probability of unemployment after obtaining a university degree; and in the proportion of university budgets used for financial support of students. In addition, there is some national variation by gender and over time in the return to a university education. This study finds that higher tuition levels in the 1990s did reduce the probability of university participation by persons aged 17,18 or 19 relative to a province-specific trend increase in university participation. Before drawing a policy conclusion from this result, it would be necessary to consider what the trend terms represent in the university participation decision.tuition fees; enrollment
Cold cathode gauge experiment (ALSEP)
Cold cathode ionization gages were left on the lunar surface as part of ALSEP (Apollo Lunar Surface Experiment Package) on Apollo missions 12, 14, and 15. An instrument prepared for Apollo 13 did not reach the surface because of the abort of that mission. The gages that reached the lunar surface measured the amounts of gas present in the vicinity of the ALSEP sites. The observed daytime gas concentrations were initially about two orders of magnitude greater than the nighttime observations; this was due to contamination of the landing area by the Apollo operations and equipment, and the daytime measurements showed a decrease with time characterized by a time constant of a few months
Multi-Agent Complex Systems and Many-Body Physics
Multi-agent complex systems comprising populations of decision-making
particles, have many potential applications across the biological,
informational and social sciences. We show that the time-averaged dynamics in
such systems bear a striking resemblance to conventional many-body physics. For
the specific example of the Minority Game, this analogy enables us to obtain
analytic expressions which are in excellent agreement with numerical
simulations.Comment: Accepted for publication in Europhysics Letter
Individual heterogeneity generates explosive system network dynamics
Individual heterogeneity is a key characteristic of many real-world systems,
from organisms to humans. However its role in determining the system's
collective dynamics is typically not well understood. Here we study how
individual heterogeneity impacts the system network dynamics by comparing
linking mechanisms that favor similar or dissimilar individuals. We find that
this heterogeneity-based evolution can drive explosive network behavior and
dictates how a polarized population moves toward consensus. Our model shows
good agreement with data from both biological and social science domains. We
conclude that individual heterogeneity likely plays a key role in the
collective development of real-world networks and communities, and cannot be
ignored.Comment: 6 pages, 4 figure
Applications of aerospace technology in the public interest: Pollution measurement
This study of selected NASA contributions to the improvement of pollution measurement examines the pervasiveness and complexity of the economic, political, and social issues in the environmental field; provides a perspective on the relationship between the conduct of aerospace R and D and specific improvements in on site air pollution monitoring equipment now in use; describes the basic relationship between the development of satellite-based monitoring systems and their influence on long-term progress in improving environmental quality; and comments on how both instrumentation and satellite remote sensing are contributing to an improved environment. Examples of specific gains that have been made in applying aerospace R and D to environmental problem-solving are included
Predictability of large future changes in a competitive evolving population
The dynamical evolution of many economic, sociological, biological and
physical systems tends to be dominated by a relatively small number of
unexpected, large changes (`extreme events'). We study the large, internal
changes produced in a generic multi-agent population competing for a limited
resource, and find that the level of predictability actually increases prior to
a large change. These large changes hence arise as a predictable consequence of
information encoded in the system's global state.Comment: 10 pages, 3 figure
Chebychev trajectory optimization program /CHEBYTOP 2/ Final report
Computer program for electric propelled spacecraft interplanetary, flyby, and rendezvous trajectory optimization based on Chebyshev approximation and polynomial representation
Riding and handling qualities of light aircraft: A review and analysis
Design procedures and supporting data necessary for configuring light aircraft to obtain desired responses to pilot commands and gusts are presented. The procedures employ specializations of modern military and jet transport practice where these provide an improvement over earlier practice. General criteria for riding and handling qualities are discussed in terms of the airframe dynamics. Methods available in the literature for calculating the coefficients required for a linearized analysis of the airframe dynamics are reviewed in detail. The review also treats the relation of spin and stall to airframe geometry. Root locus analysis is used to indicate the sensitivity of airframe dynamics to variations in individual stability derivatives and to variations in geometric parameters. Computer programs are given for finding the frequencies, damping ratios, and time constants of all rigid body modes and for generating time histories of aircraft motions in response to control inputs. Appendices are included presenting the derivation of the linearized equations of motion; the stability derivatives; the transfer functions; approximate solutions for the frequency, damping ratio, and time constants; an indication of methods to be used when linear analysis is inadequate; sample calculations; and an explanation of the use of root locus diagrams and Bode plots
- …