1,203 research outputs found

    RSK tableaux and the weak order on fully commutative permutations

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    For each fully commutative permutation, we construct a "boolean core," which is the maximal boolean permutation in its principal order ideal under the right weak order. We partition the set of fully commutative permutations into the recently defined crowded and uncrowded elements, distinguished by whether or not their RSK insertion tableaux satisfy a sparsity condition. We show that a fully commutative element is uncrowded exactly when it shares the RSK insertion tableau with its boolean core. We present the dynamics of the right weak order on fully commutative permutations, with particular interest in when they change from uncrowded to crowded. In particular, we use consecutive permutation patterns and descents to characterize the minimal crowded elements under the right weak order.Comment: 20 pages, 2 figure

    Runs and RSK tableaux of boolean permutations

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    We define and construct the "canonical reduced word" of a boolean permutation, and show that the RSK tableaux for that permutation can be read off directly from this reduced word. We also describe those tableaux that can correspond to boolean permutations, and enumerate them. In addition, we generalize a result of Mazorchuk and Tenner, showing that the "run" statistic influences the shape of the RSK tableau of arbitrary permutations, not just of those that are boolean.Comment: 18 pages, 3 figure

    Diversity in Engineering Technology Students

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    In the US, there are two academic pathways to a career in engineering: Engineering and Engineering Technology (ET). Engineering Technology attracts more African American and Latin American students than traditional engineering programs. Nationally, African American students are more than twice as likely to enroll in an ET program versus Engineering. We suspect it may be due to traditional Engineering programsā€™ requirement of higher levels of math and science classes, often lacking in under-privileged or underserved urban or rural high schools. Recently published research by the New York Equity Coalition supports this supposition. Understanding the reasons for the higher representation of these students in ET can provide insights on the background of these students for developing effective practices and programming to improve retention of this cohort. It would also provide useful information for increasing the diversity of traditional engineering programs. This paper presents initial findings from a work in progress that is part of a multi-institution study to understand the factors that influence initial matriculation into and retention in engineering technology programs

    The Effect of Magnification Loupes on Dental Hygienists\u27 Posture While Exploring

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    Purpose: The purpose of this study was to determine the effects of dental magnification loupes on posture during instrumentation. Methods: A convenience sample of 27 right-handed dental hygienists, with no prior history of injuries or disabilities of the head, neck, or trunk region, enrolled in the study. Baseline posture calibration was taken and tri-axial accelerometers were placed on four locations of the head and trunk (occipital region of head; cervical vertebrae C5; thoracic vertebrae T5; lumbar vertebrae L1) to measure acceleration and the orientation of the body to gravity. Participants were randomly assigned to wear self-supplied magnification loupes during either the first or second half of the session. Dental chair mounted typodonts, prepared with artificial calculus, were used to represent a simulated oral environment. Participants were asked to explore all areas of the mouth using an ODU 11/12 explorer. Mean accelerations of the three axes were used to compute average forward/backward (AP) and side to side (ML) tilt of each accelerometer recorded during the instrumentation sessions. An end-user opinion survey was completed by each participant at the conclusion of the session. Results: No statistically significant differences in posture were revealed between the sessions with the participants wearing their loupes and not wearing loupes. However, data from the end-user survey indicate that 74% of all the participants strongly agreed that magnification loupes made exploring easier and 67% strongly agreed that they felt that magnification loupes improved their posture. Conclusion: While the majority of participants perceived that their magnification loupes enhanced their posture and made exploring easier, data from this study provided little evidence to suggest that wearing loupes leads to improved body orientation. Future research needs to examine the declination angle of ergonomic loupes and its relationship to neck and trunk flexion

    Engineering Technology Undergraduate Students: A Survey of Demographics and Mentoring

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    A report published by a group of engineering technology practitioners and others interested in engineering technology called ā€œEngineering Technology Education in the United Statesā€ was released in early 2017. The report provided recommendations of areas for further study related to engineering technology students to increase our understanding of the population. These specifically suggested focusing on the students in comparison to other students in similar and different fields of study. Following these recommendations, a team of engineering technology education researchers has been collaborating to gather information in these areas. The team obtained institutional approval and distributed two surveys throughout the United States. The first survey was directed towards undergraduate students and the other towards those who have already completed their undergraduate degrees. This paper is focused on a high-level review of the results of the undergraduate survey, with future, in-depth publications focused on the issues identified by the report. The survey was designed to address the issues described in the report focused on matriculation, retention, and graduation from engineering technology. In this case, we are examining the demographics of undergraduate engineering technology students, mentoring, and other issues that participants self-reported, as related to their peers in other STEAM (Science, Technology, Engineering, Arts and Mathematics) majors. Later work will focus more on program (2-year vs 4-year) comparisons, socioeconomic issues, and level of preparation for the various majors categorized as STEAM. This paper is not intended to provide responses to the recommendations of the National Academy of Engineering (NAE) report, but rather provide an overview of the responses to the inquiry focused on addressing this topic. The undergraduate engineering technology student subset of the STEAM survey respondents is about 68% male and 30% female. This is as expected, recognizing that engineering technology and related disciplines tend to be male dominated. The reporting students most frequently identified as white, followed by Asian and Hispanic. Most students attended a suburban, public high school and about 47% of students reported receiving no support as they prepared to attend college

    Nanoparticle growth following photochemical Ī±ā€ and Ī²ā€pinene oxidation at Appledore Island during International Consortium for Research on Transport and Transformation/Chemistry of Halogens at the Isles of Shoals 2004

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    Nanoparticle events were observed 48 times in particle size distributions at Appledore Island during the International Consortium for Atmospheric Research on Transport and Transformation/Chemistry of Halogens on the Isles of Shoals (ICARTT/CHAiOS) field campaign from 2 July to 12 August of 2004. Eighteen of the nanoparticle events showed particle growth and occurred during mornings when peaks in mixing ratios of Ī±ā€ and Ī²ā€pinene and ozone made production of condensable products from photochemical oxidation probable. Many pollutants and other potential precursors for aerosol formation were also at elevated mixing ratios during these events, including NO, HNO3, NH3, HCl, propane, and several other volatile organic carbon compounds. There were no consistent changes in particle composition, although both submicron and supermicron particles included high maximum concentrations of methane sulfonate, sulfate, iodide, nitrate, and ammonium during these events. Nanoparticle growth continued over several hours with a nearly linear rate of increase of diameter with time. The observed nanoparticle growth rates varied from 3 to 13 nm hāˆ’1. Apparent nanoparticle aerosol mass fractions (yields) were estimated to range from less than 0.0005 to almost 1 using Ī±ā€ and Ī²ā€pinene as the presumed particle source. These apparent high aerosol mass fractions (yields) at low changes in aerosol mass are up to two orders of magnitude greater than predictions from extrapolated laboratory parameterizations and may provide a more accurate assessment of secondary organic aerosol formation for estimating the growth of nanoparticles in global models

    Western Spruce Budworm and Wildfire: Is There a Connection?

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    In the interior Pacific Northwest, extensive defoliation of mixed conifer forests during outbreaks of western spruce budworm (WSB) may leave the visual impression of a tinderbox with trees primed to burst into flame. But is this the case? We addressed this question with funding from the USDA/U.S. Department of the Interior Joint Fire Science Program (project 09ā€“ 1ā€“06ā€“5). Here we summarize our three recent publications exploring the potential relationship between WSB outbreaks and fire. We used a multimethod approach to explore potential disturbance interactions that might cause one disturbance to change the occurrence or severity of the other. We used tree-ring records to see whether WSB and fire are related in time and computer modeling to see how defoliation could affect crown fire behavior

    Microplastics in European sea salts ā€“ An example of exposure through consumer choice and of interstudy methodological discrepancies

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    Microplastics are contaminants of emerging concern, not least due to their global presence in marine surface waters. Unsurprisingly, microplastics have been reported in salts harvested from numerous locations. We extracted microplastics from 13 European sea salts through 30% H2O2 digestion and filtration over 5-Āµm filters. Filters were visually inspected at magnifications to x100. A subsample of potential microplastics was subjected to Raman spectroscopy. Particle mass was estimated, and human dose exposure calculated. After blank corrections, median concentrations were 466 Ā± 152 microplastics kg-1 ranging from 74 to 1155 items kg-1. Traditionally harvested salts contained fewer microplastics than most industrially harvested ones (t-test, p < 0.01). Approximately 14 Āµg of microplastics (< 12 particles) may be absorbed by the human body annually, of which a quarter may derive from a consumer choosing sea salt. We reviewed existing studies, showing that targeting different particle sizes and incomplete filtrations hinder interstudy comparison, indicating the importance of method harmonisation for future studies. Excess salt consumption is detrimental to human health; the hazardousness of ingesting microplastics on the other hand has yet to be shown. A portion of microplastics may enter sea salts through production processes rather than source materials

    Advances in actinomycete research: an ActinoBase review of 2019

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    The actinomycetes are Gram-positive bacteria belonging to the order Actinomycetales within the phylum Actinobacteria. They include members with significant economic and medical importance, for example filamentous actinomycetes such as Streptomyces species, which have a propensity to produce a plethora of bioactive secondary metabolites and form symbioses with higher organisms, such as plants and insects. Studying these bacteria is challenging, but also fascinating and very rewarding. As a Microbiology Society initiative, members of the actinomycete research community have been developing a Wikipedia-style resource, called ActinoBase, the purpose of which is to aid in the study of these filamentous bacteria. This review will highlight 10 publications from 2019 that have been of special interest to the ActinoBase community, covering 4 major components of actinomycete research: (i) development and regulation; (ii) specialized metabolites; (iii) ecology and host interactions; and (iv) technology and methodology
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