Lighting energy efficiency opportunities at Cheyenne Mountain Air Station

CMAS is an intensive user of electricity for lighting because of its size, lack of daylight, and 24-hour operating schedule. Argonne National Laboratory recently conducted a lighting energy conservation evaluation at CMAS. The evaluation included inspection and characterization of existing lighting systems, analysis of energy-efficient retrofit options, and investigation of the environmental effects that these lighting system retrofits could have when they are ready to be disposed of as waste. Argonne devised three retrofit options for the existing lighting systems at various buildings: (1) minimal retrofit--limited fixture replacement; (2) moderate retrofit--more extensive fixture replacement and limited application of motion detectors; and (3) advanced retrofit--fixture replacement, reduction in the number of lamps, expansion of task lighting, and more extensive application of motion detectors. Argonne used data on electricity consumption to analyze the economic and energy effects of these three retrofit options. It performed a cost analysis for each retrofit option in terms of payback. The analysis showed that lighting retrofits result in savings because they reduce electricity consumption, cooling load, and maintenance costs. The payback period for all retrofit options was found to be less than 2 years, with the payback period decreasing for more aggressive retrofits. These short payback periods derived largely from the intensive (24-hours-per-day) use of electric lighting at the facility. Maintenance savings accounted for more than half of the annual energy-related savings under the minimal and moderate retrofit options and slightly less than half of these savings under the advanced retrofit option. Even if maintenance savings were excluded, the payback periods would still be impressive: about 4.4 years for the minimal retrofit option and 2 years for the advanced option. The local and regional environmental impacts of the three retrofit options were minimal

How robust are future projections of forest landscape dynamics? Insights from a systematic comparison of four forest landscape models

Projections of landscape dynamics are uncertain, partly due to uncertainties in model formulations. However, quantitative comparative analyses of forest landscape models are lacking. We conducted a systematic comparison of all forest landscape models currently applied in temperate European forests (LandClim, TreeMig, LANDIS-II, iLand). We examined the uncertainty of model projections under several future climate, disturbance, and dispersal scenarios, and quantified uncertainties by variance partitioning. While projections under past climate conditions were in good agreement with observations, uncertainty under future climate conditions was high, with between-model biomass differences of up to 200 t ha−1. Disturbances strongly influenced landscape dynamics and contributed substantially to uncertainty in model projections (~25–40% of observed variance). Overall, model differences were the main source of uncertainty, explaining at least 50% of observed variance. We advocate a more rigorous and systematic model evaluation and calibration, and a broader use of ensemble projections to quantify uncertainties in future landscape dynamics

The Poggendorff illusion affects manual pointing as well as perceptual judgements

Pointing movements made to a target defined by the imaginary intersection of a pointer with a distant landing line were examined in healthy human observers in order to determine whether such motor responses are susceptible to the Poggendorff effect. In this well-known geometric illusion observers make systematic extrapolation errors when the pointer abuts a second line (the inducer). The kinematics of extrapolation movements, in which no explicit target was present, where similar to those made in response to a rapid-onset (explicit) dot target. The results unambiguously demonstrate that motor (pointing) responses are susceptible to the illusion. In fact, raw motor biases were greater than for perceptual responses: in the absence of an inducer (and hence also the acute angle of the Poggendorff stimulus) perceptual responses were near-veridical, whilst motor responses retained a bias. Therefore, the full Poggendorff stimulus contained two biases: one mediated by the acute angle formed between the oblique pointer and the inducing line (the classic Poggendorff effect), which affected both motor and perceptual responses equally, and another bias, which was independent of the inducer and primarily affected motor responses. We conjecture that this additional motor bias is associated with an undershoot in the unknown direction of movement and provide evidence to justify this claim. In conclusion, both manual pointing and perceptual judgements are susceptible to the well-known Poggendorff effect, supporting the notion of a unitary representation of space for action and perception or else an early locus for the effect, prior to the divergence of processing streams

Rapid eye movements to a virtual target are biased by illusory context in the Poggendorff figure.

In order to determine the influence of perceptual input upon oculomotor responses, we examined rapid saccadic eye movements made by healthy human observers to a virtual target defined by the extrapolated intersection of a pointer with a distant landing line. While corresponding perceptual judgments showed no evidence of systematic bias, eye movements showed a strong bias, in the direction of assimilation of the saccade trajectory to the shortest path between the end of the pointer and the landing line. Adding an abutting vertical inducing line to make an angle of 45 deg with the pointer led to a larger bias in the same direction as the classical Poggendorff illusion. This additional Poggendorff effect was similar in direction and magnitude for the eye movements and the perceptual responses. Latency and dynamics of the eye movements were closely similar to those recorded for a control task in which observers made a saccade from the start fixation to an explicit target on the landing line. Further experiments with inducing lines presented briefly at various times during the saccade latency period showed that the magnitude of the saccade bias was affected by inducer presentation during the saccade planning process, but not during the saccade itself. We conclude that the neural mechanisms for extrapolation can feed into the control of eye movements without obvious penalties in timing and accuracy and that this information can instantaneously modify motor response throughout the planning phase, suggesting close association between perceptual and motor mechanisms in the process of visuo-spatial extrapolation

Wellsprings of a 'World War': An early English attempt to conquer Canada during King William's war, 1688-97

This is the author's PDF version of an article published in Journal of Imperial and Commonwealth History© 2006. The definitive version is available at www.tandf.co.uk/journals/FICHThis article discusses the military history of the early years of King William's War, 1688-97, including an early attempt to conquer French Canada in 1690 by Sir William Phips. The article places this within differeing interpretations of the military historiography of early modern colonial America.This article was submitted to the RAE2008 for the University of Chester - History

Perceptual judgment and saccadic behavior in a spatial distortion with briefly presented stimuli.

When observers are asked to localize the peripheral position of a small probe with respect to the mid-position of a spatially extended comparison stimulus, they tend to judge the probe as being more peripheral than the mid-position of the comparison stimulus. This relative mislocalization seems to emerge from differences in absolute localization, that is the comparison stimulus is localized more towards the fovea than the probe. The present study compared saccadic behaviour and relative localization judgements in three experiments and determined the quantitative relationship between both measures. The results showed corresponding effects in localization errors and saccadic behaviour. Moreover, it was possible to estimate the amount of the relative mislocalization by means of the saccadic amplitude

Grasping Kinematics from the Perspective of the Individual Digits: A Modelling Study

Grasping is a prototype of human motor coordination. Nevertheless, it is not known what determines the typical movement patterns of grasping. One way to approach this issue is by building models. We developed a model based on the movements of the individual digits. In our model the following objectives were taken into account for each digit: move smoothly to the preselected goal position on the object without hitting other surfaces, arrive at about the same time as the other digit and never move too far from the other digit. These objectives were implemented by regarding the tips of the digits as point masses with a spring between them, each attracted to its goal position and repelled from objects' surfaces. Their movements were damped. Using a single set of parameters, our model can reproduce a wider variety of experimental findings than any previous model of grasping. Apart from reproducing known effects (even the angles under which digits approach trapezoidal objects' surfaces, which no other model can explain), our model predicted that the increase in maximum grip aperture with object size should be greater for blocks than for cylinders. A survey of the literature shows that this is indeed how humans behave. The model can also adequately predict how single digit pointing movements are made. This supports the idea that grasping kinematics follow from the movements of the individual digits

The Brentano illusion influences goal-directed movements of the left and right hand to the same extent

Recently, Gonzalez et al. (J Neurophys 95:3496-3501, 2006) reported that movements with the left hand are more susceptible to visual size illusions than are those with the right hand. We hypothesized that this might be because proprioceptive information about the position of the left hand is less precise. If so, the difference between the hands should become clearer when vision of the hand is removed so that subjects can only rely on proprioception to locate their hand. We tested whether this was so by letting right-handed subjects make open-loop pointing movements within an illusory context with and without vision of their hand. On average, the illusion influenced the left and the right hand to the same extent, irrespective of the visibility of the hand. There were some systematic differences between the hands within certain regions of space, but these were not consistent across subjects. We conclude that there is no fundamental difference between the hands in susceptibility to the Brentano illusion