title: An Investigation into Landing Approach Visual Illusions

authors: Reynolds, Natalie Beth

subjects: aviation

abstract: This experiment was designed to examine aspects of human visual perception during approaches to a runway. The runway width illusion has commonly been reported to contribute to the dangerous tendency of pilots to fly low approaches to runways that are wide and high approaches to runways that are narrow. Attempts to prevent the runway width illusion have not attempted to identify the ideal location for an indicator of altitude. Thus the present experiment examined the effect of varying runway width and manipulated scenes in order to determine whether the runway width illusion was present and where participants were focusing their attention in the scenes. Thirty-two non-pilot participants and 3 pilots took part in the experiment and viewed static and dynamic scenes of runways that were narrow (30.48m), medium (60.96m) or wide (91.44m) at one of three viewing heights low (30.48m), medium (45.72m) or high (60.96m). After viewing scenes, participants were required to estimate their altitude and aim-point. The results of this experiment revealed that participants were fairly inaccurate at estimating altitude and were inclined to overestimate aim-point, however the data also indicated that there was a robust runway width illusion that was present across static and dynamic trials and in both altitude and aim-point data. The standard marking on the runway in an attempt to prevent the runway width illusion was not effective at preventing incorrect altitude estimations but did assist participants to estimate aim-point. It was also found that the objects that participants' most commonly reported using to estimate altitude in the visual scene were located in the lower segment of the scenes.

text: An Investigation into Landing Approach Visual Illusions This experiment was designed to examine aspects of human visual perception during approaches to a runway. The runway width illusion has commonly been reported to contribute to the dangerous tendency of pilots to fly low approaches to runways that are wide and high approaches to runways that are narrow. Attempts to prevent the runway width illusion have not attempted to identify the ideal location for an indicator of altitude. Thus the present experiment examined the effect of varying runway width and manipulated scenes in order to determine whether the runway width illusion was present and where participants were focusing their attention in the scenes. Thirty-two non-pilot participants and 3 pilots took part in the experiment and viewed static and dynamic scenes of runways that were narrow (30.48m), medium (60.96m) or wide (91.44m) at one of three viewing heights low (30.48m), medium (45.72m) or high (60.96m). After viewing scenes, participants were required to estimate their altitude and aim-point. The results of this experiment revealed that participants were fairly inaccurate at estimating altitude and were inclined to overestimate aim-point, however the data also indicated that there was a robust runway width illusion that was present across static and dynamic trials and in both altitude and aim-point data. The standard marking on the runway in an attempt to prevent the runway width illusion was not effective at preventing incorrect altitude estimations but did assist participants to estimate aim-point. It was also found that the objects that participants' most commonly reported using to estimate altitude in the visual scene were located in the lower segment of the scenes.

year: 2007

title: The design of an optimistic AND-parallel Prolog

authors: Cleary, John G.

subjects: Computer Science

abstract: A distributed AND-parallel Prolog implementation is described.  The system can correctly handle all pure Prolog programs.  In particular, it deals with the problem of distributed backtracking.  Conflicts in variable bindings are resolved by assigning a time value to every unification. Bindings with smaller time values are given precedence over those with larger time values.  The algorithm is based on the optimistic Time Warp system, with Prolog-specific optimizations.  The optimizations include two new unification algorithms that permit unification and backtracking in any order.  The result is a system which can fully exploit the parallelism available in both dependent and independent AND-parallelism.

text: The design of an optimistic AND-parallel Prolog A distributed AND-parallel Prolog implementation is described.  The system can correctly handle all pure Prolog programs.  In particular, it deals with the problem of distributed backtracking.  Conflicts in variable bindings are resolved by assigning a time value to every unification. Bindings with smaller time values are given precedence over those with larger time values.  The algorithm is based on the optimistic Time Warp system, with Prolog-specific optimizations.  The optimizations include two new unification algorithms that permit unification and backtracking in any order.  The result is a system which can fully exploit the parallelism available in both dependent and independent AND-parallelism.

year: 1993-10

title: ‘Inside Out’: The politics of enumerating the nation by ethnicity

authors: Kukutai, Tahu

abstract: Since the 1990s, state practices of counting and classifying populations by ethnicity have come under increased scrutiny within the social sciences (Arel 2002 ; Kertzer and Arel 2002 ; Nobles 2000 ; Perlmann and Waters 2002 ; Petersen 1997 ; Statistics Canada and U.S. Census Bureau 1993 ). A number of excellent case studies have provided critical insights into how and why ethnic enumeration is pursued in particular times and places. ¹ However, with some notable exceptions (Morning 2008 ; Rallu
et al. 2006 ), little attention has been given to theorizing or empirically testing a global
model of ethnic classifi cation and counting. Consequently, there is a limited understanding
about the general conditions that impede or encourage state recognition of ethnicity in the national census and the forms that such recognition takes.

text: ‘Inside Out’: The politics of enumerating the nation by ethnicity Since the 1990s, state practices of counting and classifying populations by ethnicity have come under increased scrutiny within the social sciences (Arel 2002 ; Kertzer and Arel 2002 ; Nobles 2000 ; Perlmann and Waters 2002 ; Petersen 1997 ; Statistics Canada and U.S. Census Bureau 1993 ). A number of excellent case studies have provided critical insights into how and why ethnic enumeration is pursued in particular times and places. ¹ However, with some notable exceptions (Morning 2008 ; Rallu
et al. 2006 ), little attention has been given to theorizing or empirically testing a global
model of ethnic classifi cation and counting. Consequently, there is a limited understanding
about the general conditions that impede or encourage state recognition of ethnicity in the national census and the forms that such recognition takes.

year: 2015