946 research outputs found

    Hexahydrite (MgSO46H2O) as an Effloreschence of Some Ohio Dolomites

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    Author Institution: Department of Mineralogy, The Ohio State University, Columbus 10 Ohio Division of Geological Survey, Columbu

    Cornea organoids from human induced pluripotent stem cells.

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    The cornea is the transparent outermost surface of the eye, consisting of a stratified epithelium, a collagenous stroma and an innermost single-cell layered endothelium and providing 2/3 of the refractive power of the eye. Multiple diseases of the cornea arise from genetic defects where the ultimate phenotype can be influenced by cross talk between the cell types and the extracellular matrix. Cell culture modeling of diseases can benefit from cornea organoids that include multiple corneal cell types and extracellular matrices. Here we present human iPS cell-derived organoids through sequential rounds of differentiation programs. These organoids share features of the developing cornea, harboring three distinct cell types with expression of key epithelial, stromal and endothelial cell markers. Cornea organoid cultures provide a powerful 3D model system for investigating corneal developmental processes and their disruptions in diseased conditions

    Security for Grid Services

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    Grid computing is concerned with the sharing and coordinated use of diverse resources in distributed "virtual organizations." The dynamic and multi-institutional nature of these environments introduces challenging security issues that demand new technical approaches. In particular, one must deal with diverse local mechanisms, support dynamic creation of services, and enable dynamic creation of trust domains. We describe how these issues are addressed in two generations of the Globus Toolkit. First, we review the Globus Toolkit version 2 (GT2) approach; then, we describe new approaches developed to support the Globus Toolkit version 3 (GT3) implementation of the Open Grid Services Architecture, an initiative that is recasting Grid concepts within a service oriented framework based on Web services. GT3's security implementation uses Web services security mechanisms for credential exchange and other purposes, and introduces a tight least-privilege model that avoids the need for any privileged network service.Comment: 10 pages; 4 figure

    Planning and developing services for diabetic retinopathy in Sub-Saharan Africa

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    Background: Over the past few decades diabetes has emerged as an important non-communicable disease in Sub- Saharan Africa (SSA). Sight loss from Diabetic Retinopathy (DR) can be prevented with screening and early treatment. The objective of this paper is to outline the required actions and considerations in the planning and development of DR screening services. Methods: A multiple-case study approach was used to analyse five DR screening services in Botswana, Ghana, Tanzania and Zambia. Cases included: two regional screening programmes, two hospital-based screening services and one nationwide screening service. Data was collected using qualitative methodologies including: document analysis, in- depth interviews and observation. The World Health Organization (WHO) Health Systems Framework was adopted as the conceptual framework for analysis. Results: Planning for a sustainable and integrated DR screening programme demanded a health systems approach. Collaboration with representatives from a variety of ministerial departments and professional bodies was required. Evolution of DR screening services may occur in a variety of ways including: increasing geographical coverage, integration into the general healthcare system, and stepwise progression from a passive, opportunistic service to one that systematically and proactively seeks to prevent DR. Lessons learned from the implementation of cervical cancer prevention programmes in resource-poor settings may assist the development of DR programmes in similar settings. Conclusion: To promote good planning of DR screening services and ensure limited resources are used effectively, there is a need to learn from screening programmes in other medical specialities and a need to share experiences between newly-developing DR programmes in resource-poor countries. The WHO Health Systems Framework presents an invaluable tool to ensure a systematic approach to planning DR screening service

    The Extreme Hosts of Extreme Supernovae

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    We use GALEX ultraviolet (UV) and optical integrated photometry of the hosts of 17 luminous supernovae (LSNe, having peak M_V 100 M_☉), by appearing in low-SFR hosts, are potential tests for theories of the initial mass function that limit the maximum mass of a star based on the SFR

    Online privacy fatigue:a scoping review and research agenda

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    Online users are responsible for protecting their online privacy themselves: the mantra is custodiat te (protect yourself). Even so, there is a great deal of evidence pointing to the fact that online users generally do not act to preserve the privacy of their personal information, consequently disclosing more than they ought to and unwisely divulging sensitive information. Such self-disclosure has many negative consequences, including the invasion of privacy and identity theft. This often points to a need for more knowledge and awareness but does not explain why even knowledgeable users fail to preserve their privacy. One explanation for this phenomenon may be attributed to online privacy fatigue. Given the importance of online privacy and the lack of integrative online privacy fatigue research, this scoping review aims to provide researchers with an understanding of online privacy fatigue, its antecedents and outcomes, as well as a critical analysis of the methodological approaches used. A scoping review based on the PRISMA-ScR checklist was conducted. Only empirical studies focusing on online privacy were included, with nontechnological studies being excluded. All studies had to be written in English. A search strategy encompassing six electronic databases resulted in eighteen eligible studies, and a backward search of the references resulted in an additional five publications. Of the 23 studies, the majority were quantitative (74%), with fewer than half being theory driven (48%). Privacy fatigue was mainly conceptualized as a loss of control (74% of studies). Five categories of privacy fatigue antecedents were identified: privacy risk, privacy control and management, knowledge and information, individual differences, and privacy policy characteristics. This study highlights the need for greater attention to be paid to the methodological design and theoretical underpinning of future research. Quantitative studies should carefully consider the use of CB-SEM or PLS-SEM, should aim to increase the sample size, and should improve on analytical rigor. In addition, to ensure that the field matures, future studies should be underpinned by established theoretical frameworks. This review reveals a notable absence of privacy fatigue research when modeling the influence of privacy threats and invasions and their relationship with privacy burnout, privacy resignation, and increased self-disclosure. In addition, this review provides insight into theoretical and practical research recommendations that future privacy fatigue researchers should consider going forward

    Hollowed-out genring as a way of purposefully embracing troublesome knowledge: orientation and de-orientation in the learning and teaching of Fine Art

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    This text emerges from ongoing research focused on pedagogical developments within the curriculum of the Year 0 Fine Art Pathway, at Norwich University of the Arts. Within any subject discipline, including Fine Art, there are threshold concepts (Meyer and Land, 2003, p.1) that can represent troublesome knowledge (Meyer and Land, 2003, p.2); knowledge that must be comprehended in order that students succeed within that discipline. Within the teaching and learning of Fine Art, students will work between both written and visual genres, often struggling to rationalise the two. As part of our research we have developed practiced based research tasks that serve as destabilising prompts, a hollowed out genre, that encourages students to enter into a de-orientated, liminal, conceptual space within their learning. With the introduction of reflective models, students are able to navigate this liminal space and are afforded opportunities for developmental re-orientations, thus beginning to embrace the threshold concepts inherent with the Fine Art discipline. Drawing upon examples of current practice and student learning, we demonstrate how a process of genring and the use of reflective tools encourage students to confront aspects of troublesome knowledge and see critical writing as an important facet of their practice

    Enzymatic engineering of the porcine genome with transposons and recombinases

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    <p>Abstract</p> <p>Background</p> <p>Swine is an important agricultural commodity and biomedical model. Manipulation of the pig genome provides opportunity to improve production efficiency, enhance disease resistance, and add value to swine products. Genetic engineering can also expand the utility of pigs for modeling human disease, developing clinical treatment methodologies, or donating tissues for xenotransplantation. Realizing the full potential of pig genetic engineering requires translation of the complete repertoire of genetic tools currently employed in smaller model organisms to practical use in pigs.</p> <p>Results</p> <p>Application of transposon and recombinase technologies for manipulation of the swine genome requires characterization of their activity in pig cells. We tested four transposon systems- <it>Sleeping Beauty</it>, <it>Tol2</it>, <it>piggyBac</it>, and <it>Passport </it>in cultured porcine cells. Transposons increased the efficiency of DNA integration up to 28-fold above background and provided for precise delivery of 1 to 15 transgenes per cell. Both Cre and Flp recombinase were functional in pig cells as measured by their ability to remove a positive-negative selection cassette from 16 independent clones and over 20 independent genomic locations. We also demonstrated a Cre-dependent genetic switch capable of eliminating an intervening positive-negative selection cassette and activating GFP expression from episomal and genome-resident transposons.</p> <p>Conclusion</p> <p>We have demonstrated for the first time that transposons and recombinases are capable of mobilizing DNA into and out of the porcine genome in a precise and efficient manner. This study provides the basis for developing transposon and recombinase based tools for genetic engineering of the swine genome.</p

    Gluelump Spectrum in the Bag Model

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    We explore the ordering of the lowest levels in a simple bag model of the ``gluelump'' of Michael and also discuss, again within the context of the bag model, the related problem of hybrid potentials in the limit of very small spacing between quark and anti-quark sources.Comment: 10 page

    A Nanocryotron Memory and Logic Family

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    The development of superconducting electronics based on nanocryotrons has been limited so far to few-device circuits, in part due to the lack of standard and robust logic cells. Here, we introduce and experimentally demonstrate designs for a set of nanocryotron-based building blocks that can be configured and combined to implement memory and logic functions. The devices were fabricated by patterning a single superconducting layer of niobium nitride and measured in liquid helium on a wide range of operating points. The tests show 10410^{-4} bit error rates with above 20%20\,\% margins up to 5050\,MHz and the possibility of operating under the effect of a perpendicular 3636\,mT magnetic field, with 30%30\,\% margins at 1010\,MHz. Additionally, we designed and measured an equivalent delay flip-flop made of two memory cells to show the possibility of combining multiple building blocks to make larger circuits. These blocks may constitute a solid foundation for the development of nanocryotron logic circuits and finite-state machines with potential applications in the integrated processing and control of superconducting nanowire single-photon detectors.Comment: Submitted for publication in the Applied Physics Letters special issue "Advances in Superconducting Logic", 8 pages, 5 figure
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