597 research outputs found

    Diverter AI based decision aid, phases 1 and 2

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    It was determined that a system to incorporate artificial intelligence (AI) into airborne flight management computers is feasible. The AI functions that would be most useful to the pilot are to perform situational assessment, evaluate outside influences on the contemplated rerouting, perform flight planning/replanning, and perform maneuver planning. A study of the software architecture and software tools capable of demonstrating Diverter was also made. A skeletal planner known as the Knowledge Acquisition Development Tool (KADET), which is a combination script-based and rule-based system, was used to implement the system. A prototype system was developed which demonstrates advanced in-flight planning/replanning capabilities

    Uncertainty in relief supply distribution

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    In the aftermath of a natural disaster the efficient planning of humanitarian relief efforts, e.g., delivering supplies to locations in need, can often mean the difference between lives being saved and lives being lost. In this paper we focus on two things: (1) appropriate objectives for routing problems in the context of delivery of relief supplies, and (2) how to handle the uncertainty associated with delivery of relief supplies after a disaster. Through applying uncertainty to parameters such as travel time between locations, we seek to examine if/how optimal routes change as a result of different objectives and the presence of uncertainty. After discussing various different parameters and examining the effects of uncertainty in these cases, we then offer up an algorithmic process that could be used in the formation of these routes using the uncertain information. Finally, we analyze the results of a simulation model that ran different routes using information known with certainty and uncertain information, and see what light it sheds on the disaster response discussion

    Estimation of viral richness from shotgun metagenomes using a frequency count approach

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    BACKGROUND: Viruses are important drivers of ecosystem functions, yet little is known about the vast majority of viruses. Viral shotgun metagenomics enables the investigation of broad ecological questions in phage communities. One ecological characteristic is species richness, which is the number of different species in a community. Viruses do not have a phylogenetic marker analogous to the bacterial 16S rRNA gene with which to estimate richness, and so contig spectra are employed to measure the number of virus taxa in a given community. A contig spectrum is generated from a viral shotgun metagenome by assembling the random sequence reads into groups of sequences that overlap (contigs) and counting the number of sequences that group within each contig. Current tools available to analyze contig spectra to estimate phage richness are limited by relying on rank-abundance data. RESULTS: We present statistical estimates of virus richness from contig spectra. The program CatchAll (http://www.northeastern.edu/catchall/) was used to analyze contig spectra in terms of frequency count data rather than rank-abundance, thus enabling formal statistical analyses. Also, the influence of potentially spurious low-frequency counts on richness estimates was minimized by two methods, empirical and statistical. The results show greater estimates of viral richness than previous calculations in nearly all environments analyzed, including swine feces and reclaimed fresh water. CONCLUSIONS: CatchAll yielded consistent estimates of richness across viral metagenomes from the same or similar environments. Additionally, analysis of pooled viral metagenomes from different environments via mixed contig spectra resulted in greater richness estimates than those of the component metagenomes. Using CatchAll to analyze contig spectra will improve estimations of richness from viral shotgun metagenomes, particularly from large datasets, by providing statistical measures of richness

    Maximizing the Benefits of Participatory Design for Human–Robot Interaction Research With Older Adults

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    Objective We reviewed human–robot interaction (HRI) participatory design (PD) research with older adults. The goal was to identify methods used, determine their value for design of robots with older adults, and provide guidance for best practices. Background Assistive robots may promote aging-in-place and quality of life for older adults. However, the robots must be designed to meet older adults’ specific needs and preferences. PD and other user-centered methods may be used to engage older adults in the robot development process to accommodate their needs and preferences and to assure usability of emergent assistive robots. Method This targeted review of HRI PD studies with older adults draws on a detailed review of 26 articles. Our assessment focused on the HRI methods and their utility for use with older adults who have a range of needs and capabilities. Results Our review highlighted the importance of using mixed methods and including multiple stakeholders throughout the design process. These approaches can encourage mutual learning (to improve design by developers and to increase acceptance by users). We identified key phases used in HRI PD workshops (e.g., initial interview phase, series of focus groups phase, and presentation phase). These approaches can provide inspiration for future efforts. Conclusion HRI PD strategies can support designers in developing assistive robots that meet older adults’ needs, capabilities, and preferences to promote acceptance. More HRI research is needed to understand potential implications for aging-in-place. PD methods provide a promising approach

    Literature-based reading instruction: Problems, possibilities & polemics in the struggle to change

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    Concerns are being raised in both professional literature as well as in the popular press regarding certain aspects of the literature-based movement. Here we report on findings from a longitudinal study of a group of first -grade teachers who have been attempting (with varying degrees of success)to introduce literature-based teaching strategies into their classrooms. We inspect the experiences of these teachers in relation to four areas of concern that have been raised regarding literature-based teaching: 1. skills instruction; 2.guided reading strategies; 3. literature selection;and 4. thematic teaching (or curriculum integration). We describe classroom practices and the 9 problems and possibilities associated with teacher change in each of the four areas

    Mobility Disability in Older Adults: At the Intersection of People and Places

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    Mobility disability is associated with poor lower body function among older adults. This study examines whether specific types of neighborhood characteristics moderate that association

    Perseverative behaviour in fluent and non-fluent aphasic adults

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    Perseveration by type (recurrent, continuous, or stuck-in-set) was examined for 30 stroke patients, 20 of whom exhibited fluent aphasia, and 10 with non-fluent aphasia. Comparisons were made between the two aphasic subject groups on two verbal and two non-verbal tasks. Twenty-eight of the patients (93%) produced at least one instance of perseveration. The most commonly occurring type was recurrent perseveration. Instances of continuous perseveration also were common and were produced by 18 patients. Stuck-in-set perseveration was uncommon with only two patients exhibiting this form of perseveration. No differences were observed in the frequency of perseveration across the four tasks between fluent and non-fluent aphasic patients. Perseveration was significantly correlated with aphasia severity, but not with time post-onset

    Low levels of β-lactam antibiotics induce extracellular DNA release and biofilm formation in Staphylococcus aureus.

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    UNLABELLED: Subminimal inhibitory concentrations of antibiotics have been shown to induce bacterial biofilm formation. Few studies have investigated antibiotic-induced biofilm formation in Staphylococcus aureus, an important human pathogen. Our goal was to measure S. aureus biofilm formation in the presence of low levels of β-lactam antibiotics. Fifteen phylogenetically diverse methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains were employed. Methicillin, ampicillin, amoxicillin, and cloxacillin were added to cultures at concentrations ranging from 0× to 1× MIC. Biofilm formation was measured in 96-well microtiter plates using a crystal violet binding assay. Autoaggregation was measured using a visual test tube settling assay. Extracellular DNA was quantitated using agarose gel electrophoresis. All four antibiotics induced biofilm formation in some strains. The amount of biofilm induction was as high as 10-fold and was inversely proportional to the amount of biofilm produced by the strain in the absence of antibiotics. MRSA strains of lineages USA300, USA400, and USA500 exhibited the highest levels of methicillin-induced biofilm induction. Biofilm formation induced by low-level methicillin was inhibited by DNase. Low-level methicillin also induced DNase-sensitive autoaggregation and extracellular DNA release. The biofilm induction phenotype was absent in a strain deficient in autolysin (atl). Our findings demonstrate that subminimal inhibitory concentrations of β-lactam antibiotics significantly induce autolysin-dependent extracellular DNA release and biofilm formation in some strains of S. aureus. IMPORTANCE: The widespread use of antibiotics as growth promoters in agriculture may expose bacteria to low levels of the drugs. The aim of this study was to investigate the effects of low levels of antibiotics on bacterial autoaggregation and biofilm formation, two processes that have been shown to foster genetic exchange and antibiotic resistance. We found that low levels of β-lactam antibiotics, a class commonly used in both clinical and agricultural settings, caused significant autoaggregation and biofilm formation by the important human pathogen Staphylococcus aureus. Both processes were dependent on cell lysis and release of DNA into the environment. The effect was most pronounced among multidrug-resistant strains known as methicillin-resistant S. aureus (MRSA). These results may shed light on the recalcitrance of some bacterial infections to antibiotic treatment in clinical settings and the evolution of antibiotic-resistant bacteria in agricultural settings
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