5,378 research outputs found

    An Extensible Benchmarking Infrastructure for Motion Planning Algorithms

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    Sampling-based planning algorithms are the most common probabilistically complete algorithms and are widely used on many robot platforms. Within this class of algorithms, many variants have been proposed over the last 20 years, yet there is still no characterization of which algorithms are well-suited for which classes of problems. This has motivated us to develop a benchmarking infrastructure for motion planning algorithms. It consists of three main components. First, we have created an extensive benchmarking software framework that is included with the Open Motion Planning Library (OMPL), a C++ library that contains implementations of many sampling-based algorithms. Second, we have defined extensible formats for storing benchmark results. The formats are fairly straightforward so that other planning libraries could easily produce compatible output. Finally, we have created an interactive, versatile visualization tool for compact presentation of collected benchmark data. The tool and underlying database facilitate the analysis of performance across benchmark problems and planners.Comment: Submitted to IEEE Robotics & Automation Magazine (Special Issue on Replicable and Measurable Robotics Research), 201

    A dysphoric's TALE: The relationship between the self-reported functions of autobiographical memory and symptoms of depression

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    Autobiographical memory (AM) is believed to serve self, social and directive functions; however, little is known regarding how this triad of functions operates in depression. Using the Thinking About Life Experiences questionnaire [Bluck, S., & Alea, N. (2011). Crafting the TALE: Construction of a measure to assess the functions of autobiographical remembering. Memory, 19, 470ā€“486.; Bluck, S., Alea, N., Habermas, T., & Rubin, D. C. (2005). A TALE of three functions: The selfā€“reported uses of autobiographical memory. Social Cognition, 23, 91ā€“117.], two studies explored the relationship between depressive symptomology and the self-reported frequency and usefulness of AMs for self, social and directive purposes. Study 1 revealed that thinking more frequently but talking less frequently about past life events was significantly associated with higher depression scores. Recalling past events more frequently to maintain self-continuity was also significantly associated with higher depressive symptomology. However, results from Study 2 indicated that higher levels of depression were also significantly associated with less-frequent useful recollections of past life events for self-continuity purposes. Taken together, the findings suggest atypical utilisations of AM to serve self-continuity functions in depression and can be interpreted within the wider context of ruminative thought processes

    Vortex-enhanced propulsion

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    It has been previously suggested that the generation of coherent vortical structures in the near-wake of a self-propelled vehicle can improve its propulsive efficiency by manipulating the local pressure field and entrainment kinematics. This paper investigates these unsteady mechanisms analytically and in experiments. A self-propelled underwater vehicle is designed with the capability to operate using either steady-jet propulsion or a pulsed-jet mode that features the roll-up of large-scale vortex rings in the near-wake. The flow field is characterized by using a combination of planar laser-induced fluorescence, laser Doppler velocimetry and digital particle-image velocimetry. These tools enable measurement of vortex dynamics and entrainment during propulsion. The concept of vortex added-mass is used to deduce the local pressure field at the jet exit as a function of the shape and motion of the forming vortex rings. The propulsive efficiency of the vehicle is computed with the aid of towing experiments to quantify hydrodynamic drag. Finally, the overall vehicle efficiency is determined by monitoring the electrical power consumed by the vehicle in steady and unsteady propulsion modes. This measurement identifies conditions under which the power required to create flow unsteadiness is offset by the improved vehicle efficiency. The experiments demonstrate that substantial increases in propulsive efficiency, over 50 % greater than the performance of the steady-jet mode, can be achieved by using vortex formation to manipulate the near-wake properties. At higher vehicle speeds, the enhanced performance is sufficient to offset the energy cost of generating flow unsteadiness. An analytical model explains this enhanced performance in terms of the vortex added-mass and entrainment. The results suggest a potential mechanism to further enhance the performance of existing engineered propulsion systems. In addition, the analytical methods described here can be extended to examine more complex propulsion systems such as those of swimming and flying animals, for whom vortex formation is inevitable

    Survival processing versus self-reference : a memory advantage following descriptive self-referential encoding

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    Previous research has shown that rating words for their relevance to a survival scenario leads to better retention of the words than rating them for self-reference. Past studies have, however, relied exclusively on an autobiographical self-reference task in which participants rate how easily a common noun brings to mind a personal experience. We report five experiments comparing survival processing to a descriptive self-reference task in which participants rated how well trait words described them. Rating trait adjectives for survival value led to higher levels of recall and recognition than rating them for their relevance to a moving home scenario. Rating the adjectives for self-reference, however, led to higher levels of recall (Experiments 1 and 3) and recollection (Experiment 2) than survival rating. Experiment 4 replaced trait adjectives with trait nouns and found that self-reference led to greater recognition accuracy than survival processing. Experiment 5 used trait nouns followed by tests of free recall and found a memory advantage following self-reference that was not influenced by the imageability of the stimuli. The findings are discussed in terms of theories of the survival processing and self-reference effects and the relationship between them

    Consuming transgenic goats' milk containing the antimicrobial protein lysozyme helps resolve diarrhea in young pigs.

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    Childhood diarrhea is a significant problem in many developing countries and E. coli is a main causative agent of diarrhea in young children. Lysozyme is an antimicrobial protein highly expressed in human milk, but not ruminant milk, and is thought to help protect breastfeeding children against diarrheal diseases. We hypothesized that consumption of milk from transgenic goats which produce human lysozyme (hLZ-milk) in their milk would accelerate recovery from bacterial-induced diarrhea. Young pigs were used as a model for children and infected with enterotoxigenic E. coli. Once clinical signs of diarrhea developed, pigs were fed hLZ-milk or non-transgenic control goat milk three times a day for two days. Clinical observations and complete blood counts (CBC) were performed. Animals were euthanized and samples collected to assess differences in histology, cytokine expression and bacterial translocation into the mesenteric lymph node. Pigs consuming hLZ-milk recovered from clinical signs of infection faster than pigs consuming control milk, with significantly improved fecal consistency (p = 0.0190) and activity level (p = 0.0350). The CBC analysis showed circulating monocytes (p = 0.0413), neutrophils (p = 0.0219), and lymphocytes (p = 0.0222) returned faster to pre-infection proportions in hLZ-milk fed pigs, while control-fed pigs had significantly higher hematocrit (p = 0.027), indicating continuing dehydration. In the ileum, pigs fed hLZ-milk had significantly lower expression of pro-inflammatory cytokine IL-8 (p = 0.0271), longer intestinal villi (p<0.0001), deeper crypts (p = 0.0053), and a thinner lamina propria (p = 0.0004). These data demonstrate that consumption of hLZ-milk helped pigs recover from infection faster, making hLZ-milk an effective treatment of E. coli-induced diarrhea

    Adaptive false memory: Imagining future scenarios increases false memories in the DRM paradigm

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    Previous research has shown that rating words for their relevance to a future scenario enhances memory for those words. The current study investigated the effect of future thinking on false memory using the Deese/Roedigerā€“McDermott (DRM) procedure. In Experiment 1, participants rated words from 6 DRM lists for relevance to a past or future event (with or without planning) or in terms of pleasantness. In a surprise recall test, levels of correct recall did not vary between the rating tasks, but the future rating conditions led to significantly higher levels of false recall than the past and pleasantness conditions did. Experiment 2 found that future rating led to higher levels of false recognition than did past and pleasantness ratings but did not affect correct recognition. The effect in false recognition was, however, eliminated when DRM items were presented in random order. Participants in Experiment 3 were presented with both DRM lists and lists of unrelated words. Future rating increased levels of false recognition for DRM lures but did not affect correct recognition for DRM or unrelated lists. The findings are discussed in terms of the view that false memories can be associated with adaptive memory functions

    The Effects of Locus of Control and Death Education on Death Attitudes

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    The relationship of locus of control and death education on death attitudes was examined across a population of college students. Students beginning a death education course, students finishing a death education course, and mortuary science students, completed Rotter\u27s I-E scale, Hardt\u27s Death Attitude Scale, and questions on personal beliefs. No significant difference of death attitude was found between the three groups, although internality was found to be significantly correlated to favorable death attitude. Statistical analysis did not support the hypothesis that death education positively affects death attitudes, however, the data do reveal that those individuals with an internal locus of control and who also received some type of death education, exhibited the most favorable attitudes toward death. No significant differences were found for sex, amount of religion, or experience of recent death. Further study is necessary

    Alien Registration- Quarrington, Lydia A. (Portland, Cumberland County)

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    https://digitalmaine.com/alien_docs/21556/thumbnail.jp

    Review of \u3cem\u3eOpposites: Blue Sky White Stars\u3c/em\u3e by Sarvinder Naberhaus

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    https://digitalcommons.cedarville.edu/intern_book_reviews/1198/thumbnail.jp

    Review of \u3cem\u3eOpposites: Frederick Douglass : the lion who wrote history\u3c/em\u3e by Walter Dean Myers

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    https://digitalcommons.cedarville.edu/intern_book_reviews/1206/thumbnail.jp
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