37,457 research outputs found

    Miniature sonar fish tag

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    Self-powered sonar device may be implanted in body of fish. It transmits signal that can be detected with portable tracking gear or by automatic detection-and-tracking system. Operating life of over 4000 hours may be expected. Device itself may be used almost indefinitely

    Epidemiology and burden of nasal congestion

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    Nasal congestion, which may be described as fullness, obstruction, reduced airflow, or being "stuffed up," is a commonly encountered symptom in clinical practice. Systematic study of congestion has largely considered it as a component of a disease state. Conditions associated with congestion include nasal polyposis, obstructive sleep apnea, and anatomic variation; however, most information on the burden of congestion comes from studies of allergic rhinitis and rhinosinusitis, diseases of which congestion is the major symptom. Congestion can be caused by other rhinologic conditions, such as non-allergic rhinitis, viral or bacterial rhinitis, and vasomotor rhinitis. Allergic rhinitis affects as much as one quarter of the population worldwide and imposes a significant economic burden. Additionally, allergic rhinitis significantly impairs quality of life; congestion causes allergic rhinitis sufferers decreased daytime productivity at work or school and reduces night-time sleep time and quality. Annually, rhinosinusitis affects tens of millions of Americans and leads to approximately $6 billion in overall health care expenditures; it has been found to be one of the most costly physical conditions for US employers. Given the high prevalence and significant social and economic burden of nasal congestion, this symptom should be a key consideration in treating patients with rhinologic disease, and there continues to be a significant unmet medical need for effective treatment options for this condition. © 2010 Stewart et al

    To Sell and to Provide? The Economic and Environmental Implications of the Auto Manufacturer's Involvement in the Car Sharing Business

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    Motivated by the involvement of Daimler and BMW in the car sharing business we consider an OEM who contemplates introducing a car sharing program. The OEM designs its product line by accounting for the trade-off between driving performance and fuel efficiency. Customers have different valuations of driving performance and decide whether to buy, join car sharing, or rely on their outside option. Car sharing can increase the profit from selling. This happens when the OEM prefers to serve the lower-end customers through car sharing and the higher-end through selling. In this case, car sharing increases the efficiency of the vehicles used for the lower-end, and the price charged to the higher-end customers. This is more pronounced for higher-end OEMs, which may help explain Daimler's and BMW's involvement in car sharing. Despite the higher efficiency, car sharing may lower the OEM's Corporate Average Fuel Economy (CAFE) level even when it increases profit and decreases environmental impact. CAFE levels better reflect the environmental benefits of car sharing when they are based on the number of customers served and not the production volume. Finally, if anticipating aggressive CAFE standards, OEMs may include car sharing to better absorb the increase in the production cost

    Maladaptive rumination moderates the effects of written emotional disclosure on ambulatory blood pressure levels in females.

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    Written emotional disclosure (WED) has beneficial effects on health outcomes. However, its effectiveness is influenced by a number of variables. This exploratory study tested whether trait rumination, which comprises brooding, a maladaptive component, and reflection, an adaptive component, moderated the effects of WED on ambulatory blood pressure (ABP) in female participants. Fifty-two participants were randomized to write about their most stressful/traumatic life experience(s) or non-emotive topics, for 20 minutes, on 3 consecutive days. Two weeks and 14 weeks later, ABP was recorded over a single day. Using hierarchical linear modelling, an effect of condition was found at 2 weeks but not at 14 weeks indicating that higher levels of ABP were observed following WED. There was also a significant condition by brooding interaction at two weeks such that higher ABP was observed in low brooders in the WED condition compared with low brooders in the control condition. However, within the WED condition, the lowest ABP was exhibited by participants high in brooding. The findings indicated that WED led to short-lived increases in ABP which disappeared in the medium term. Researchers ought to build upon this exploratory study and investigate further the potential moderating role of brooding within WED. Individual differences in brooding may account for (some of) the mixed and inconsistent findings in past WED research

    Improving the viability of mental models held by novice programmers

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    Recent research has found that many novice programmers often hold non-viable mental models of basic programming concepts such as assignment and object reference. This paper proposes a constructivist-based teaching model, integrating a cognitive conflict strategy with program visualization, with the aim of improving novice programmers’ mental models. The results of a preliminary empirical study suggest that, for the relatively straightforward concept of assignment, tight integration of program visualization with a cognitive conflict event that highlights a student’s inappropriate understanding can help improve students’ non-viable mental models. 14 out of 18 participants who held non-viable mental models of the assignment process successfully changed their model to be viable as a result of the proposed teaching model

    Microgravity nucleation and particle coagulation experiments support

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    A preliminary model for diffusion between concentric hemispheres was adapted to the cylindrical geometry of a microgravity nucleation apparatus, and extended to include the effects of radiation and conduction through the containment walls. Computer programs were developed to calculate first the temperature distribution and then the evolving concentration field using a finite difference formulation of the transient diffusion and radiation processes. The following estimations are made: (1) it takes approximately 35 minutes to establish a steady temperature field; (2) magnesium vapors released into the argon environment at the steady temperature distribution will reach a maximum supersaturation ratio of approximately 10,000 in the 20-second period at a distance of 15 cm from the source of vapors; and (3) approximately 750W electrical power will be required to maintain steady operating temperatures within the chamber

    Sound Source Localization in a Multipath Environment Using Convolutional Neural Networks

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    The propagation of sound in a shallow water environment is characterized by boundary reflections from the sea surface and sea floor. These reflections result in multiple (indirect) sound propagation paths, which can degrade the performance of passive sound source localization methods. This paper proposes the use of convolutional neural networks (CNNs) for the localization of sources of broadband acoustic radiated noise (such as motor vessels) in shallow water multipath environments. It is shown that CNNs operating on cepstrogram and generalized cross-correlogram inputs are able to more reliably estimate the instantaneous range and bearing of transiting motor vessels when the source localization performance of conventional passive ranging methods is degraded. The ensuing improvement in source localization performance is demonstrated using real data collected during an at-sea experiment.Comment: 5 pages, 5 figures, Final draft of paper submitted to 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) 15-20 April 2018 in Calgary, Alberta, Canada. arXiv admin note: text overlap with arXiv:1612.0350
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