816 research outputs found

    Detecting Signals of Species’ Ecological Niches in Results of Studies with Defined Sampling Protocols: Example Application to Pathogen Niches

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    Ecological niches are increasingly appreciated as a long-term stable constraint on the geographic and temporal distributions of species, including species involved in disease transmission cycles (pathogens, vectors, hosts). Although considerable research effort has used correlative methodologies for characterizing niches, sampling effort (and the biases that this effort may or may not carry with it) considerations have generally not been incorporated explicitly into ecological niche modeling. In some cases, however, the sampling effort can be characterized explicitly, such as when hosts are tested for pathogens, as well as comparable situations such as when traps are deployed to capture particular species, etc. Here, we present simple methods for testing the hypothesis that non-randomness in occurrence or detection exists with respect to environmental dimensions (= a detectable signal of ecological niche); i.e., whether a pathogen occurs nonrandomly with respect to environment, given the occurrence and sampling of its host. We have implemented a set of R functions that presents an overall test for nonrandom occurrence with respect to a set of environmental dimensions, and, a posteriori, a set of exploratory tests that identify in which dimension(s) and in which direction or form the nonrandom occurrence is manifested. Our tools correctly detected signals of niche in most of our example cases. Although such signal may not be detectable in cases in which the niche of interest is broader than the universe sampled, such a possibility was correctly discarded in our analyses, preventing further interpretations. This kind of testing can constitute an initial step in a process that would conclude with development of a more typical ecological niche model. The particular advantage of the analyses proposed is that they consider the biases involved in sampling, testing, and reporting, in the context of nonrandom occurrence with respect to environment before proceeding to inferential and predictive steps

    A Rapid Survey of the Critically Endangered Zapata Toad, Peltophryne florentinoi (Anura: Bufonidae), in Cuba: New Locality and Conservation Approaches

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    We provide new distributional data for the most geographically restricted and threatened Cuban toad, the Zapata Toad (Peltophryne florentinoi), and evaluate this information for its potential conservation implications. Prior to this survey, the species was known from only one locality. Although our records extend the geographic distribution about 20 km to the east from the previous locality, unsuitable habitats limited the species’ true extent of occurrence. Intermittent salt-water lagoons, local lithographic features, and anthropogenic disturbances impede the continuity of the toad’s distribution along the coastal forests. New surveys and long-term monitoring protocols could offer better clues about the distribution, biology, and conservation status of this species

    Analysis of cooling limitations and effect of engine-cooling improvements on level-flight cruising performance of four-engine heavy bomber

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    The NACA has developed means, including an injection impeller and ducted head baffles, to improve the cooling characteristics of the 3350-cubic-inch-displacement radial engines installed in a four-engine heavy bomber. The improvements afforded proper cooling of the rear-row exhaust-valve seats for a wide range of cowl-flap angles, mixture strengths, and airplane speeds. The results of flight tests with this airplane are used as a basis for a study to determine the manner and the extent to which the airplane performance was limited by engine cooling. By means of this analysis for both the standard airplane and the airplane with engine-cooling modifications, comparison of the specific range at particular conditions and comparison of the cruising-performance limitations was made

    Teachers’ reading promotion activities:Variation, structure and correlates

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    The purpose of this study is to determine which different forms of reading promotion activities teachers perform in fifth and sixth grade in The Netherlands and whether different forms of reading promotion activities are acted out independently or cluster into meaningful categories of reading promotion behavior. A survey was administered to 194 teachers and data was analyzed using Principal Component Analyses (PCA). Based on the results of the PCA thirteen different types of reading promotion behavior can be distinguished. Specific teacher and class characteristics are connected with the different types of reading promotion activities teachers perform. Teachers seem to be mainly focusing on promoting the reading of fictional texts. Free reading happens most often, and teachers frequently use comics and short stories in class. Most daily activities take little or no preparation. Correlations are small but do suggest that teachers act out more different forms of reading promotion activities when there are more girls are in class than boys. Also, classes with more girls act out more activities concerning new media and nonfiction

    Individual Incentives versus Team Performance: Lessons from a Game of Charades

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    In this article, we describe a modified game of Charades that was developed to facilitate a discussion on the basic principles of effective reward system design. Students are organized into small groups. Incentive schemes are then manipulated so that one player within the group strives for an individual incentive, while the rest of the team play for a group reward. Through this simple and “fun” activity, students learn firsthand what happens when individual and team interests and incentives are not aligned. This experiential learning activity also offers excellent opportunities to discuss group dynamics, communication and coordination, and the importance of maintaining a systemic view of organizational performance

    AliasNet: Alias Artefact Suppression Network for Accelerated Phase-Encode MRI

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    Sparse reconstruction is an important aspect of MRI, helping to reduce acquisition time and improve spatial-temporal resolution. Popular methods are based mostly on compressed sensing (CS), which relies on the random sampling of k-space to produce incoherent (noise-like) artefacts. Due to hardware constraints, 1D Cartesian phase-encode under-sampling schemes are popular for 2D CS-MRI. However, 1D under-sampling limits 2D incoherence between measurements, yielding structured aliasing artefacts (ghosts) that may be difficult to remove assuming a 2D sparsity model. Reconstruction algorithms typically deploy direction-insensitive 2D regularisation for these direction-associated artefacts. Recognising that phase-encode artefacts can be separated into contiguous 1D signals, we develop two decoupling techniques that enable explicit 1D regularisation and leverage the excellent 1D incoherence characteristics. We also derive a combined 1D + 2D reconstruction technique that takes advantage of spatial relationships within the image. Experiments conducted on retrospectively under-sampled brain and knee data demonstrate that combination of the proposed 1D AliasNet modules with existing 2D deep learned (DL) recovery techniques leads to an improvement in image quality. We also find AliasNet enables a superior scaling of performance compared to increasing the size of the original 2D network layers. AliasNet therefore improves the regularisation of aliasing artefacts arising from phase-encode under-sampling, by tailoring the network architecture to account for their expected appearance. The proposed 1D + 2D approach is compatible with any existing 2D DL recovery technique deployed for this application

    Individual Incentives versus Team Performance: Lessons from a Game of Charades

    Get PDF
    In this article, we describe a modified game of Charades that was developed to facilitate a discussion on the basic principles of effective reward system design. Students are organized into small groups. Incentive schemes are then manipulated so that one player within the group strives for an individual incentive, while the rest of the team play for a group reward. Through this simple and “fun” activity, students learn firsthand what happens when individual and team interests and incentives are not aligned. This experiential learning activity also offers excellent opportunities to discuss group dynamics, communication and coordination, and the importance of maintaining a systemic view of organizational performance

    A practical guide for the study of human and murine sebaceous glands in situ

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    The skin of most mammals is characterised by the presence of sebaceous glands (SGs), whose predominant constituent cell population is sebocytes, that is, lipid-producing epithelial cells, which develop from the hair follicle. Besides holocrine sebum production (which contributes 90% of skin surface lipids), multiple additional SG functions have emerged. These range from antimicrobial peptide production and immunomodulation, via lipid and hormone synthesis/metabolism, to the provision of an epithelial progenitor cell reservoir. Therefore, in addition to its involvement in common skin diseases (e.g. acne vulgaris), the unfolding diversity of SG functions, both in skin health and disease, has raised interest in this integral component of the pilosebaceous unit. This practical guide provides an introduction to SG biology and to relevant SG histochemical and immunohistochemical techniques, with emphasis placed on in situ evaluation methods that can be easily employed. We propose a range of simple, established markers, which are particularly instructive when addressing specific SG research questions in the two most commonly investigated species in SG research, humans and mice. To facilitate the development of reproducible analysis techniques for the in situ evaluation of SGs, this methods review concludes by suggesting quantitative (immuno-)histomorphometric methods for standardised SG evaluation

    Heterogeneity in the spread and control of infectious disease: consequences for the elimination of canine rabies

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    Understanding the factors influencing vaccination campaign effectiveness is vital in designing efficient disease elimination programmes. We investigated the importance of spatial heterogeneity in vaccination coverage and human-mediated dog movements for the elimination of endemic canine rabies by mass dog vaccination in Region VI of the Philippines (Western Visayas). Household survey data was used to parameterise a spatially-explicit rabies transmission model with realistic dog movement and vaccination coverage scenarios, assuming a basic reproduction number for rabies drawn from the literature. This showed that heterogeneous vaccination reduces elimination prospects relative to homogeneous vaccination at the same overall level. Had the three vaccination campaigns completed in Region VI in 2010–2012 been homogeneous, they would have eliminated rabies with high probability. However, given the observed heterogeneity, three further campaigns may be required to achieve elimination with probability 0.95. We recommend that heterogeneity be reduced in future campaigns through targeted efforts in low coverage areas, even at the expense of reduced coverage in previously high coverage areas. Reported human-mediated dog movements did not reduce elimination probability, so expending limited resources on restricting dog movements is unnecessary in this endemic setting. Enhanced surveillance will be necessary post-elimination, however, given the reintroduction risk from long-distance dog movements

    Putting People at the Center: The Role of Lived Experience in Dismantling Collateral Consequences Caused by Incarceration

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    These are the slides for the webinar "Putting People at the Center: The Role of Lived Experience in Dismantling Collateral Consequences Caused by Incarceration" held August 1, 2017. The goal of this webinar was to acknowledge that policy and systems change is most authentic and impactful when it surfaces and is driven from lived experience. It also explored the ways in which organizations partner with and learn from people most impacted in their decision making and processes driving policy change in criminal justice reforms related to employment, housing, and other collateral consequences of incarceration.The group of panelists included Marlon Chamberlain with FORCE Organizer at the Community Renewal Society, Glenn E. Martin from JustLeadershipUSA (JLUSA), Michelle Natividad Rodriguezfrom the National Employment Law Project (NELP), and Quintin Williams with Heartland Alliance
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