82,523 research outputs found

    Transportation Futures: Policy Scenarios for Achieving Greenhouse Gas Reduction Targets, MNTRC Report 12-11

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    It is well established that GHG emissions must be reduced by 50% to 80% by 2050 in order to limit global temperature increase to 2°C. Achieving reductions of this magnitude in the transportation sector is a challenge and requires a multitude of policies and technology options. The research presented here analyzes three scenarios: changes in the perceived price of travel, land-use intensification, and increases in transit. Elasticity estimates are derived using an activity-based travel model for the state of California and broadly representative of the U.S. The VISION model is used to forecast changes in technology and fuel options that are currently forecast to occur in the U.S., providing a life cycle GHG forecast for the road transportation sector. Results suggest that aggressive policy action is needed, especially pricing policies, but also more on the technology side. Medium- and heavy-duty vehicles are in particular need of additional fuel or technology-based GHG reductions

    Foreword and Prologue

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    Milton Konvitz (Ph.D. \u2733) embodied the spirit of Cornell University. An authority on civil rights and human rights, and constitutional and labor law, he served on the Cornell faculty for 27 years, holding dual appointments at the Law School and the School of Industrial and Labor Relations. This section includes the foreword by Robert B. McKersie and the prologue in four chapters: (1) The Making of a Scholar; (2) Civil Rights; (3) Fundamental Liberties; and (4) Judaic and American Ideals

    Telemetric longitudinal measurement of young driver behaviour

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    New Zealand is one of the few countries that currently allows teenagers to become solo drivers at 15 Âœ years of age. During their first six months of solo driving, these teenagers are 19 times more likely to crash compared to the period of supervised driving. The behaviour of these adolescent drivers represents the single largest cause of fatalities in that age group and is widely acknowledged as one of the most serious social issues facing New Zealand. This state of affairs, often referred to as ‘the young driver problem,’ with an over representation of young drivers in motor vehicle crashes, is not unique to New Zealand. In fact, a similar situation can be found inmost of the world’s developed nations

    The ‘frontal lobe’ project: A double-blind, randomized controlled study of the effectiveness of higher level driving skills training to improve frontal lobe (executive) function related driving performance in young drivers

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    The current study was undertaken in order to evaluate the effectiveness of higher level skills training on safe driving behaviour of 36 teenage drivers. The participants, who attended the Driver Training Research camp in Taupo (NZ) over a two week period, were 16 to 17 years old and had a valid restricted driver licence. The study focused on four main aims. Firstly, the behavioural characteristics of the sample and their attitudes to risk taking and driving were examined. Results showed that speeding was the most anticipated driving violation, and high levels of confidence were associated with a higher number of crashes and a greater propensity for risk taking. Many, often male participants, also rated their driving skills as superior to others and thought they would be less likely than others to be involved in an accident. Secondly, the relationship between driving performance and executive functioning, general ability and sustained attention was evaluated. Overall, better driving performance and more accurate self-evaluation of driving performance was related to higher levels of executive functions, in particular, working memory, and cognitive switching. In addition, higher general ability and greater ability to sustain attention were also linked to better performance on the driving related assessments. The third focus of this study was to compare the effects of both, higher level and vehicle handling skills training on driving performance, confidence levels and attitudes to risk. While both types of training improved direction control, speed choice and visual search, along with number of hazards detected and actions in relation to hazards, statistically significant improvement on visual search was seen only after higher level skills training. Vehicle handling skills training significantly improved direction control and speed choice. In addition, confidence levels in their driving skills were significantly lowered and attitudes to speeding, overtaking and close following had improved significantly in the participants after the higher level driving skills training. The final aspect to this study was to examine the effects of the training over the following 6 month period based on self-reported driving behaviour. The response rate of participants however, was not sufficient to reach any meaningful conclusion on any long-term training effects. A pilot study using GPSbased data trackers to assess post-training driving behaviour revealed some promising results for future driver training evaluation studies. The overall implications of the results are discussed in relation to improving the safety of young drivers in New Zealand

    Evaluation of a sudden brake warning system: Effect on the response time of the following driver

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    This study used a video-based braking simulation dual task to carry out a preliminary evaluation of the effect of a sudden brake warning system (SBWS) in a leading passenger vehicle on the response time of the following driver. The primary task required the participants (N = 25, 16 females, full NZ license holders) to respond to sudden braking manoeuvres of a lead vehicle during day and night driving, wet and dry conditions and in rural and urban traffic, while concurrently performing a secondary tracking task using a computer mouse. The SBWS in the lead vehicle consisted of g-force controlled activation of the rear hazard lights (the rear indicators flashed), in addition to the standard brake lights. Overall, the results revealed that responses to the braking manoeuvres of the leading vehicles when the hazard lights were activated by the warning system were 0.34 s (19%) faster compared to the standard brake lights. The SBWS was particularly effective when the simulated braking scenario of the leading vehicle did not require an immediate and abrupt braking response. Given this, the SBWS may also be beneficial for allowing smoother deceleration, thus reducing fuel consumption. These preliminary findings justify a larger, more ecologically valid laboratory evaluation which may lead to a naturalistic study in order to test this new technology in ‘real world’ braking situations

    There is no MacWilliams identity for convolutional codes

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    An example is provided of two convolutional codes that have the same transmission gain but whose dual codes do not. This shows that no analog of the MacWilliams identity for block codes can exist relating the transmission gains of a convolutional code and its dual

    How Did E. M. Walker Measure the Length of the Labium of Nymphs of \u3ci\u3eAeshna\u3c/i\u3e and \u3ci\u3eRhionaeschna\u3c/i\u3e (Odonata: Aeshnidae)?

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    The exhaustive studies of nymphs of Aeshna Fabricius and Rhionaeschna Förster by E. M. Walker (1912-1958) have long guided the taxonomy of these groups and formed the basis for keys still in use today. However, uncertainty about how he measured the length of the labium, including the varied terminology he used over the duration of his career concerning this structure, has led to confusion about application of his taxonomic recommendations. We recalculated ratios of the maximum width/length [W(max)/L] by measuring the illustration dimensions of folded labia and prementums in publications throughout his career and compared these data with the ratios he stated in those publications and with ratios derived from measurements of specimens in our collections. Our results show that from 1912 to 1941, Walker restricted length measurement to the prementum proper (which he called the “mentum of the labium”), exclusive of the ventrally visible portion of the postmental hinge. However, in 1941 he reported ratios from length measurements done two ways, excluding the postmental hinge in his description of the nymph of A. verticalis Hagen, but including the hinge in his description of the nymph of A. septentrionalis Burmeister (Whitehouse 1941). In Walker’s most recent and influential work (1958), he included the postmental hinge in labium length measurements of nine species, but restricted length measurements to the prementum for five others. He was consistent with the use of terms, using both “folded labium” by which he meant the prementum plus the postmental hinge, and “prementum” by which he meant only that structure. However, Walker’s descriptions of the labium in his latest work are buried in long, frequently punctuated sentences that for most species include the terms “folded labium” and “prementum” in the same sentence, so careful reading is required to know which term is intended in the width/length ratio. Width/length ratios we each calculated independently were invariably similar for a given species and were usually similar to Walker’s stated ratio for that species. These similarities affirm our conclusion that while labium measurements must be done with care, they are closely repeatable among workers and will consistently lead to correct determinations in properly designed couplets of dichotomous keys to these genera. We recommend measuring the length of the prementum proper in future studies of these genera when labium ratios are calculated because we found less variability in those cases than when the measurements included the postmental hinge. An approximate conversion between the two methods of calculating W(max)/L ratios can be made as follows: ratio calculated when the length of the prementum excluding the postmental hinge is used x 0.88 is approximately equal to the ratio when the postmental hinge is included for species of Aeshna and Rhionaeschna in North America

    Toward a Minimum Branching Fraction for Dark Matter Annihilation into Electromagnetic Final States

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    Observational limits on the high-energy neutrino background have been used to place general constraints on dark matter that annihilates only into standard model particles. Dark matter particles that annihilate into neutrinos will also inevitably branch into electromagnetic final states through higher-order tree and loop diagrams that give rise to charged leptons, and these charged particles can transfer their energy into photons via synchrotron radiation or inverse Compton scattering. In the context of effective field theory, we calculate the loop-induced branching ratio to charged leptons and show that it is generally quite large, typically >1%, when the scale of the dark matter mass exceeds the electroweak scale, M_W. For a branching fraction >3%, the synchrotron radiation bounds on dark matter annihilation are currently stronger than the corresponding neutrino bounds in the interesting mass range from 100 GeV to 1 TeV. For dark matter masses below M_W, our work provides a plausible framework for the construction of a model for "neutrinos only" dark matter annihilations.Comment: 18 pages, 4 figures, discussion added, matches version in Phys. Rev.
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