Orbital Deflection of Comets by Directed Energy

Cometary impacts pose a long-term hazard to life on Earth. Impact mitigation techniques have been studied extensively, but they tend to focus on asteroid diversion. Typical asteroid interdiction schemes involve spacecraft physically intercepting the target, a task feasible only for targets identified decades in advance and in a narrow range of orbits---criteria unlikely to be satisfied by a threatening comet. Comets, however, are naturally perturbed from purely gravitational trajectories through solar heating of their surfaces which activates sublimation-driven jets. Artificial heating of a comet, such as by a laser, may supplement natural heating by the Sun to purposefully manipulate its path and thereby avoid an impact. Deflection effectiveness depends on the comet's heating response, which varies dramatically depending on factors including nucleus size, orbit and dynamical history. These factors are incorporated into a numerical orbital model to assess the effectiveness and feasibility of using high-powered laser arrays in Earth orbit and on the ground for comet deflection. Simulation results suggest that a diffraction-limited 500 m orbital or terrestrial laser array operating at 10 GW for 1% of each day over 1 yr is sufficient to fully avert the impact of a typical 500 m diameter comet with primary nongravitational parameter A1 = 2 x 10^-8 au d^-2. Strategies to avoid comet fragmentation during deflection are also discussed.Comment: 13 pages, 12 figures; AJ, in pres

The relationship between advertisement content and pacing on emotional responses and memory for televised political advertisements

Political advertising remains the most dominant method of political communication in the world as it is the most effective way of communicating the promise of exchange to the political market. Without a doubt the single most important, expensive and well used method of political advertising is televised political advertising. It is also an area of increasing public policy concern over the perceived impact that it is having on society's perceptions of the democratic process, institutions and stakeholders. This is especially so for negative advertising which may very well be creating a negative attitude in voters towards political offerings of exchanges, brands, institutions and stakeholders that may not be reflective of reality. Yet little research has examined if this is true and little is known about whether or not voters respond emotionally to televised political advertising, and if this response influences their memory and arousal to the message. Even more broadly how political advertising is influencing the response to the communication of political exchanges in the context of an offering of value and one of loss, and how this influences emotional response to brands, is still not yet fully understood. This thesis will therefore examine what political promise of exchange when communicated using television advertising, either of value or loss, is best remembered by voters. This will help understand how political advertising is affecting voters' memory of political exchanges and attitude to brands. It will use psychophysiological measures of skin conductance and heart rate to measure how voters respond to different types of political messages that vary on two important variables: message structure, in this thesis pace, which can influence the perceived information complexity and content of a message; and valence or if the message is negative or positive in content. This will further knowledge and understanding about whether or not negative and positive advertising (that varies by pace) is affecting the emotional responses of voters to the point where they become more aroused and better remember political messages

Automated Systems and Methods for Testing Infrared Cameras

Systems and methods are disclosed herein to provide automated testing on infrared image data to detect image quality defects. For example, in accordance with an embodiment of the present invention, image processing algorithms are disclosed to generate an image quality metric that may be compared to one or more thresholds to perform an automated test for image quality defects. For example, the image quality metric may be compared to two thresholds to determine if the corresponding infrared sensor or infrared camera is defective or not due to image quality or requires further manual inspection by test personnel

THE EFFECT OF MEDIATED IMMEDIACY UPON STATE MOTIVATION AND COGNITIVE LEARNING IN AN ONLINE LESSON

The role of teacher immediacy and its impact upon student learning within the traditional classroom has been established within the instructional communication discipline in the past 30 years. In recent years, with the advent of computer-mediated distance education (i.e. online courses), some researchers have attempted to apply the same theories and measures of concepts without making the distinction between actual teacher behavioral indicants of immediacy and student perceptions of immediacy, nor recognizing that there may be a different number of variables involved between a single lesson presented online and an entire course presented over a period of time. Building upon previous models, the Short-Term Motivational Model of Learning was proposed and tested, using survey results from 229 undergraduate students who completed an online lesson presented in six different formats, and who were tested for learning outcomes. In comparison to a direct measure of learning outcomes (number of correct test answers), it was found that the Perceived Cognitive Learning Scale correlated highly with the direct measure, while the Learning Loss Scale did not. Three of the three study hypotheses were supported. Hypothesis one proposed that higher student perception of immediacy would correlate with higher student state motivation and was supported. Hypothesis two proposed that higher student trait motivation would correlate with higher student state motivation and was supported. Hypothesis three proposed that higher student state motivation would correlate with higher student cognitive learning. Student cognitive learning determined through three measures: the Perceived Cognitive Learning Scale, pretest-posttest scores differences, and the Learning Loss Scale. Using the Perceived Cognitive Learning Scale, hypothesis three was supported. Using the pretest-posttest scores differences, hypothesis three was supported weakly. Using the Learning Loss Scale, hypothesis three was also supported weakly. In testing whether teacher behavioral indicants of immediacy, student perception of immediacy and student trait motivation would explain significant variance in student state motivation in a single lesson presented online, trait motivation failed to be a predictor. Subsequently, in testing whether all of these variables would explain significant variance in student cognitive learning (and using each of the three measures of student cognitive learning), trait motivation again failed to be a predictor. In general the results support the idea that perceived learning is affected by the degree of motivation as affected by immediacy. While an attempt to vary degrees of immediacy was not fully successful, results also suggest that adding audio to online lessons may not produce significant gains in learning when compared to text-only presentations

Pleistocene rockshelters J23 and J24, Mesa J, Pilbara, Western Australia

Two spatially close rockshelters at Mesa J in the Pilbara had relatively deep deposits and large numbers of stone artifacts distributed from top to bottom. The basal archaeological materials have been directly dated as (in the case of J24) or are inferred to be (in the case of J23) late Pleistocene in age. In J24 artefacts continued downwards throughout basal Spit 10, indicating that occupation of the rockshelter began before 27,657 cal BP, possibly thousands of years before. The distribution of stone artefacts and radiocarbon dates in J24 indicates that occupation of the rockshelter continued during the Last Glacial Maximum (LGM), providing further evidence that the Hamersley Plateau provided refuge for Aboriginal people during the cold and arid conditions of the LGM

Real-World Training for Real-World Benefits: Exploring the Impact of Practice-Based Service Evaluation Training

Service evaluation is a major part of delivering effective healthcare. It is important that the future workforce of clinical psychologists is equipped with the skills required to complete evaluations of the services that they deliver. This article investigated the extent to which practice-based Service Evaluation Projects (SEPs) completed by trainee clinical psychologists at the University of Leeds had an impact on the real-world services that commissioned them. Descriptive analysis was used to summarise the characteristics of SEPs completed over the past thirteen years and to explore feedback from semi-structured interviews held with a sample of commissioners. Thematic analysis was used to identify key themes relating to the impact of SEPs. 230 SEPs have been completed in the past thirteen years. Interviews with 15 commissioners concerning 38 individual SEPs found that the majority had a positive impact (n = 33), most of which were able to bring about a change independently of other initiatives within the service (n = 20). Almost all would have been impossible without the opportunity for clinicians to commission SEPs via the university. Three key themes emerged in terms of impact: improving processes; improving knowledge; and improving resources. Practice-based service evaluations completed by trainee clinical psychologists can lead to a positive impact on real-world services. This suggests that providing training experiences ‘in the field’ is a helpful pedagogical strategy, adding value to services as well as trainee health professionals

Long-period comet impact risk mitigation with Earth-based laser arrays

Long-period comets (LPCs) frequently transit the inner solar system, and like near-Earth asteroids (NEAs), pose a continued risk of impact with Earth. Unlike NEAs, LPCs follow nearly parabolic trajectories and approach from the distant outer solar system where they cannot be observed. An LPC on an Earth-impact trajectory is unlikely to be discovered more than a few years in advance of its arrival, even with significant advancements in sky survey detection capabilities, likely leaving insufficient time to develop and deliver an interception mission to deflect the comet. However, recent proposals have called for the development of one or more large ∼ 1 km laser arrays placed on or near Earth primarily as a means for photon propulsion of low-mass spacecraft at delta-v above what would be feasible by traditional chemical or ion propulsion methods. Such a laser array can also be directed to target and heat a threatening comet, sublimating its ices and activating jets of dust and vapor which alter the comet's trajectory in a manner similar to rocket propulsion. Simulations of directed energy comet deflection were previously developed from astrometric models of nongravitational orbital perturbations from solar heating, an analogous process that has been observed in numerous comets. These simulations are used together with the distribution of known LPC trajectories to evaluate the effect of an operational Earth-based laser array on the LPC impact risk

Modern Spectral Climate Patterns in Rhythmically Deposited Argillites of the Gowganda Formation (Early Proterozoic), Southern Ontario, Canada

Rhythmically deposited argillites of the Gowganda Formation (ca. 2.0–2.5 Ga) probably formed in a glacial setting. Drop stones and layered sedimentary couplets in the rock presumably indicate formation in a lacustrine environment with repeating freeze–thaw cycles. It is plausible that temporal variations in the thickness of sedimentary layers are related to interannual climatic variability, e.g. average seasonal temperature could have influenced melting and the amount of sediment source material carried to the lake. A sequence of layer couplet thickness measurements was made from high-resolution digitized photographs taken at an outcrop in southern Ontario, Canada. The frequency spectrum of thickness measurements displays patterns that resemble some aspects of modern climate. Coherent periodic modes in the thickness spectrum appear at 9.9–10.7 layer couplets and at 14.3 layer couplets. It is unlikely that these coherent modes result from random processes. Modern instrument records of regional temperature and rainfall display similar spectral patterns, with some datasets showing significant modes near 14 yr in both parameters. Rainfall and temperature could have affected sedimentary layering in the Gowganda argillite sequence, and climate modulation of couplet thickness emerges as the most likely explanation of the observed layering pattern. If this interpretation is correct, the layer couplets represent predominantly annual accumulations of sediment (i.e. they are varves), and the thickness spectrum provides a glimpse of Early Proterozoic climatic variability. The presence of interannual climate patterns is not unanticipated, but field evidence presented here may be of some value in developing a climate theory for the Early Proterozoic