4,219 research outputs found

    A search method for thin positions of links

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    We give a method for searching for thin positions of a given link.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol5/agt-5-42.abs.htm

    Portable Shopping Cart

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    Design a mobile modular shopping system that the user owns and has the ability to go from the user’s vehicle to the store and back to the vehicle with ease, or more specifically the least amount of physical exertion by the user. The design utilizes versatile and reusable shopping bags and/or baskets and assists in organizing groceries in a more strategic pattern. We intend to use an existing bag/basket that will fit into a fabricated cart system. This cart system will be lightweight, collapsible, and easy to store in vehicle. The entire system should be able to hold at least 100 pounds of groceries, fit into a trunk size of 20 cubic feet. The system will be designed to expedite the whole shopping process, eliminating the need to obtain and return a store owned cart to the corral or store. System should require no more than two minutes to assemble or disassemble. To minimize cost, risk, and size, a child restrain will not be included

    Bayesian total evidence dating reveals the recent crown radiation of penguins

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    The total-evidence approach to divergence-time dating uses molecular and morphological data from extant and fossil species to infer phylogenetic relationships, species divergence times, and macroevolutionary parameters in a single coherent framework. Current model-based implementations of this approach lack an appropriate model for the tree describing the diversification and fossilization process and can produce estimates that lead to erroneous conclusions. We address this shortcoming by providing a total-evidence method implemented in a Bayesian framework. This approach uses a mechanistic tree prior to describe the underlying diversification process that generated the tree of extant and fossil taxa. Previous attempts to apply the total-evidence approach have used tree priors that do not account for the possibility that fossil samples may be direct ancestors of other samples. The fossilized birth-death (FBD) process explicitly models the diversification, fossilization, and sampling processes and naturally allows for sampled ancestors. This model was recently applied to estimate divergence times based on molecular data and fossil occurrence dates. We incorporate the FBD model and a model of morphological trait evolution into a Bayesian total-evidence approach to dating species phylogenies. We apply this method to extant and fossil penguins and show that the modern penguins radiated much more recently than has been previously estimated, with the basal divergence in the crown clade occurring at ~12.7 Ma and most splits leading to extant species occurring in the last 2 million years. Our results demonstrate that including stem-fossil diversity can greatly improve the estimates of the divergence times of crown taxa. The method is available in BEAST2 (v. 2.4) www.beast2.org with packages SA (v. at least 1.1.4) and morph-models (v. at least 1.0.4).Comment: 50 pages, 6 figure

    Low Levels of Extra-Pair Paternity in a Neotropical Duetting Songbird, the Rufous-and-White Wren (Thryothorus rufalbus)

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    Molecular analyses have confirmed that the majority of socially monogamous birds follow a genetically promiscuous reproductive strategy. Most such studies, however, have addressed species of the North Temperate Zone; tropical species are grossly underrepresented, although most of Earth\u27s biodiversity is concentrated in the tropics. In this study, we describe the genetic mating strategy of the Rufous-and-white Wren (Thryothorus rufalbus), a socially monogamous duetting neotropical songbird. Over 8 years of studying a marked population in Costa Rica, we recorded genetic data from 51 broods. Microsatellite analysis of four variable loci revealed that the Rufous-and-white Wren follows a mixed reproductive strategy, where extra-pair young are found in a small minority of broods. Three of 158 nestlings (2%) were the result of extra-pair fertilizations; three of the 51 broods (6%) contained a nestling with alleles mismatched to its social father. We assigned paternity of two of the extra-pair nestlings to males in territories adjacent to the cuckolded males. During behavioral observations, we observed within-pair copulations rarely and extra-pair copulations never. The rate of extra-pair paternity we report here is lower than the average reported for socially monogamous birds in the North Temperate Zone but comparable to rates in three closely related tropical wrens. Rufous-and-white Wrens are renowned for their coordinated vocal duets. We compared rates of extra-pair paternity among socially monogamous tropical birds, contrasting four duetting species against twelve nonduetting species and found lower levels of extra-pair paternity in the former group, suggesting that duetting and low levels of extra-pair paternity are related

    Collaborating to plan efficient public health guideline evidence reviews

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    The National Institute for Health and Care Excellence (NICE) produces public health guidelines. Information specialists collaborate with technical analysts to perform systematic searches for evidence reviews (ERs). Public health ERs require searches from multiple disciplines across a range of sources leading to high volumes of results. The purpose of the project was to provide evidence to support the choice of sources for new topics. It aimed to retrospectively analyse a sample of NICE public health ERs by examining which sources retrieved publications. Medical databases found the highest proportion of publications, but smaller subject focussed databases and search techniques also contributed. These findings justify use of a range of sources for public health reviews and help the planning of ERs

    Survival and growth of mussels subsequent to hemolymph sampling for DNA

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    Parallel fabrication and single-electron charging of devices based on ordered, two-dimensional phases of organically functionalized metal nanocrystals

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    A parallel technique for fabricating single-electron, solid-state capacitance devices from ordered, two-dimensional closest-packed phases of organically functionalized metal nanocrystals is presented. The nanocrystal phases were prepared as Langmuir monolayers and subsequently transferred onto Al-electrode patterned glass substrates for device construction. Alternating current impedance measurements were carried out to probe the single-electron charging characteristics of the devices under both ambient and 77 K conditions. Evidence of a Coulomb blockade and step structure reminiscent of a Coulomb staircase is presented

    How Many and What Types of SPARQL Queries can be Answered through Zero-Knowledge Link Traversal?

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    The current de-facto way to query the Web of Data is through the SPARQL protocol, where a client sends queries to a server through a SPARQL endpoint. Contrary to an HTTP server, providing and maintaining a robust and reliable endpoint requires a significant effort that not all publishers are willing or able to make. An alternative query evaluation method is through link traversal, where a query is answered by dereferencing online web resources (URIs) at real time. While several approaches for such a lookup-based query evaluation method have been proposed, there exists no analysis of the types (patterns) of queries that can be directly answered on the live Web, without accessing local or remote endpoints and without a-priori knowledge of available data sources. In this paper, we first provide a method for checking if a SPARQL query (to be evaluated on a SPARQL endpoint) can be answered through zero-knowledge link traversal (without accessing the endpoint), and analyse a large corpus of real SPARQL query logs for finding the frequency and distribution of answerable and non-answerable query patterns. Subsequently, we provide an algorithm for transforming answerable queries to SPARQL-LD queries that bypass the endpoints. We report experimental results about the efficiency of the transformed queries and discuss the benefits and the limitations of this query evaluation method.Comment: Preprint of paper accepted for publication in the 34th ACM/SIGAPP Symposium On Applied Computing (SAC 2019
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