1,145 research outputs found

    Impact detection system

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    In an embodiment, an apparatus and method capable of determining the time and location of a projectile's impact is disclosed. In another embodiment, an apparatus and method capable of determining the time and location of a projectile's impact as well as the direction from whence the projectile came is disclosed

    Impact-Locator Sensor Panels

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    Electronic sensor systems for detecting and locating impacts of rapidly moving particles on spacecraft have been invented. Systems of this type could also be useful on Earth in settings in which the occurrence of impacts and/or the locations of impacts are not immediately obvious and there are requirements to detect and quickly locate impacts to prevent or minimize damage

    Efficacy of two ethanol-based skin antiseptics on the forehead at shorter application times

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    <p>Abstract</p> <p>Background</p> <p>Recent research suggests that alcohol-based skin antiseptics exhibit their efficacy on the resident skin flora of the forehead in less than 10 minutes. That is why we have looked at the efficacy of two ethanol-based skin antiseptics applied for 10, 2.5 and 2 minutes on skin with a high density of sebaceous glands. Each experiment was performed in a reference-controlled cross-over design with at least 20 participants. Application of isopropanol (70%, v/v) for 10 minutes to the forehead served as the reference treatment. The clear (skin antiseptic A) and coloured preparations (skin antiseptic B) contain 85% ethanol (w/w). Pre-values and post-values (immediately after the application and after 30 min) were obtained by swabbing a marked area of 5 cm<sup>2</sup> for about 10 s. Swabs were vortexed in tryptic soy broth containing valid neutralizing agents. After serial dilution aliquots were spread on tryptic soy agar. Colonies were counted after incubation of plates at 36°C for 48 h. The mean log<sub>10</sub> reduction of bacteria was calculated. The Wilcoxon matched-pairs signed-ranks test was used for a comparison of treatments.</p> <p>Results</p> <p>Skin antiseptic A applied for 10 min was significantly more effective than the reference treatment. When applied for 2.5 min (three experiments) it was significantly more effective than the reference treatment immediately after application (2.7 versus 2.2 log<sub>10</sub> reduction; p < 0.001) and equally effective after 30 min (2.8 versus 2.6 log<sub>10</sub> reduction; p = 0.053). Skin antiseptic B applied for 2.5 min (three experiments) was significantly more effective than the reference treatment both immediately after application (2.3 versus 1.9 log<sub>10</sub> reduction; p < 0.001) and after 30 min (2.5 versus 2.1 log<sub>10</sub> reduction; p = 0.002).</p> <p>Conclusion</p> <p>The clear and coloured skin antiseptics applied for 2.5 min on the skin of the forehead fulfilled the efficacy requirements for skin antisepsis. The shorter application time on skin with a high density of sebaceous glands will allow to act more efficiently in clinical practice.</p

    Generating stable molecules using imitation and reinforcement learning

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    Chemical space is routinely explored by machine learning methods to discover interesting molecules, before time-consuming experimental synthesizing is attempted. However, these methods often rely on a graph representation, ignoring 3D information necessary for determining the stability of the molecules. We propose a reinforcement learning (RL) approach for generating molecules in Cartesian coordinates allowing for quantum chemical prediction of the stability. To improve sample-efficiency we learn basic chemical rules from imitation learning (IL) on the GDB-11 database to create an initial model applicable for all stoichiometries. We then deploy multiple copies of the model conditioned on a specific stoichiometry in a RL setting. The models correctly identify low energy molecules in the database and produce novel isomers not found in the training set. Finally, we apply the model to larger molecules to show how RL further refines the IL model in domains far from the training data

    Genome-wide high-throughput screening to investigate essential genes involved in methicillin-resistant Staphylococcus aureus Sequence Type 398 survival.

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    Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) Sequence Type 398 (ST398) is an opportunistic pathogen that is able to colonize and cause disease in several animal species including humans. To better understand the adaptation, evolution, transmission and pathogenic capacity, further investigations into the importance of the different genes harboured by LA-MRSA ST398 are required. In this study we generated a genome-wide transposon mutant library in an LA-MRSA ST398 isolate to evaluate genes important for bacterial survival in laboratory and host-specific environments. The transposon mutant library consisted of approximately 1 million mutants with around 140,000 unique insertion sites and an average number of unique inserts per gene of 44.8. We identified LA-MRSA ST398 essential genes comparable to other high-throughput S. aureus essential gene studies. As ST398 is the most common MRSA isolated from pigs, the transposon mutant library was screened in whole porcine blood. Twenty-four genes were specifically identified as important for bacterial survival in porcine blood. Mutations in 23 of these genes resulted in attenuated bacterial fitness. Seven of the 23 genes were of unknown function, whereas 16 genes were annotated with functions predominantly related to carbon metabolism, pH shock and a variety of regulations and only indirectly to virulence factors. Mutations in one gene of unknown function resulted in a hypercompetitive mutant. Further evaluation of these genes is required to determine their specific relevance in blood survival.This work was funded in part by the Danish Ministry of Food, Agriculture and Fisheries (Grant no. 3304-FVFP-09-F-002-1) and The Technical University of DenmarkThis is the final published version distributed under a Creative Commons Attribution License, which can also be found on the publisher's website at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.008901

    The language faculty that wasn't : a usage-based account of natural language recursion

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    In the generative tradition, the language faculty has been shrinking—perhaps to include only the mechanism of recursion. This paper argues that even this view of the language faculty is too expansive. We first argue that a language faculty is difficult to reconcile with evolutionary considerations. We then focus on recursion as a detailed case study, arguing that our ability to process recursive structure does not rely on recursion as a property of the grammar, but instead emerges gradually by piggybacking on domain-general sequence learning abilities. Evidence from genetics, comparative work on non-human primates, and cognitive neuroscience suggests that humans have evolved complex sequence learning skills, which were subsequently pressed into service to accommodate language. Constraints on sequence learning therefore have played an important role in shaping the cultural evolution of linguistic structure, including our limited abilities for processing recursive structure. Finally, we re-evaluate some of the key considerations that have often been taken to require the postulation of a language faculty
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