2,836 research outputs found

    Harmonic Forms and Deformation of ALC metrics with Spin(7) holonomy

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    Asymptotically locally conical (ALC) metric of exceptional holonomy has an asymptotic circle bundle structure that accommodates the M theory circle in type IIA reduction. Taking Spin(7) metrics of cohomogeneity one as explicit examples, we investigate deformations of ALC metrics, in particular that change the asymptotic S^1 radius related to the type IIA string coupling constant. When the canonical four form of Spin(7) holonomy is taken to be anti-self-dual, the deformations of Spin(7) metric are related to the harmonic self-dual four forms, which are given by solutions to a system of first order differential equations, due to the metric ansatz of cohomogeneity one. We identify the L^2-normalizable solution that deforms the asymptotic radius of the M theory circle.Comment: 33 pages, no figure, minor corrections, reference adde

    Solitons and admissible families of rational curves in twistor spaces

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    It is well known that twistor constructions can be used to analyse and to obtain solutions to a wide class of integrable systems. In this article we express the standard twistor constructions in terms of the concept of an admissible family of rational curves in certain twistor spaces. Examples of of such families can be obtained as subfamilies of a simple family of rational curves using standard operations of algebraic geometry. By examination of several examples, we give evidence that this construction is the basis of the construction of many of the most important solitonic and algebraic solutions to various integrable differential equations of mathematical physics. This is presented as evidence for a principal that, in some sense, all soliton-like solutions should be constructable in this way.Comment: 15 pages, Abstract and introduction rewritten to clarify the objectives of the paper. This is the final version which will appear in Nonlinearit

    The Fully Automated and Self-Contained Operations Paradigm of the CSIM Mission

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    The Compact Spectral Irradiance Monitor (CSIM) CubeSat Mission has been collecting solar spectral irradiance (SSI) data for over two years, contributing to 40+ years of multi-mission SSI data collection. CSIM utilizes a fully automated and self-contained operations paradigm developed at the Laboratory for Atmospheric and Space Physics (LASP). LASP efficiently performs the entire operations workflow for CSIM, from planning through data processing, which nominally requires only 15 minutes of staffed operations support per week. Mission operations students at LASP are responsible for the entire planning process. They query for ground station contacts and solar observation times which are input into a suite of software tools to create the onboard stored command table and the weekly uplink plan. An automated ground station script then configures for the upcoming CSIM contacts by querying Space-Track for overflights. Within 2 minutes from the start of a pass, the script commands the UHF or S-Band antenna to point at the spacecraft, brings up the command-and-control software, and performs an initial health-and-safety check upon AOS (acquisition of signal). Automated command scripts then configure the spacecraft and upload the plan using command success logic checks. This ensures that all commands are sent and accepted by the spacecraft in-order, and without overwriting any non-expired scheduling slots. The week\u27s worth of commands is loaded within a few passes, and science collection typically starts soon after. Ground automation will detect major anomalies and notify the flight control team in real-time, allowing the operators to recover the spacecraft on the next contact and prepare a new activity plan for autonomous upload. Additionally, ground automation queries CSIM health and safety data and sends telemetry trends to the operations team for daily, weekly, and monthly health and safety checks. CSIM science data is downlinked during 1 or 2 passes per day via the S-band antenna. This data is processed twice per day via an automated data processing pipeline which requires no regular human intervention. The self-contained and automated nature of the data processing pipeline ensures that LASP scientists can access CSIM data within a few hours of being received on the ground. We discuss how this efficient single-mission, self-contained operations paradigm will be expanded to support multiple missions and external customers in the future

    An academic–practice partnership during COVID-19 pandemic: Transitioning from a clinical to virtual fellowship

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    Aims: Discuss the needed modifications that occurred to the academic–practice oncology partnership during the COVID-19 pandemic. Background: To meet the workforce needs of nurses who care for adults with cancer, an academic–practice partnership was created in 2016. The University of North Carolina at Chapel Hill School of Nursing, North Carolina Cancer Hospital and UNC Lineberger Comprehensive Cancer Center collaborated to provide structured clinical and didactic practice experiences for undergraduate nursing students interested in oncology nursing. With COVID-19, nursing students were not permitted to be in the clinical setting. Design: Discursive paper. Method: An innovative and collaborative partnership created reflective and interactive activities. The majority of the learning activities were created at the revised Bloom's taxonomy level of application or higher, with some encompassing multiple levels. Students engaged in a variety of meaningful experiences requiring multiple learning processes that promoted professional development in the interpersonal and critical thinking domains. Conclusions: Despite the challenges of COVID-19, the delivery of oncology nurse fellowship was successful because of innovative virtual strategies. Relevance to Clinical Practice: Our academic–practice partnership allowed the nursing students to develop their interpersonal and critical thinking skills without entering the clinical site. This is an approach encouraged by the authors for other schools of nursing. This manuscript is submitted as a Special Issue Discursive Article, and thus, the authors declare that an EQUATOR Checklist has not been used

    Smoking status and survival in the national comprehensive cancer network non–small cell lung cancer cohort

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    BACKGROUND: The objectives of this study were to evaluate survival among current smokers, former smokers, and never smokers who are diagnosed with non–small cell lung cancer (NSCLC). METHODS: The study included patients who participated in the National Comprehensive Cancer Network's NSCLC Database Project. Current, former, and never smokers were compared with respect to overall survival by fitting Cox regression models. RESULTS: Data from 4200 patients were examined, including 618 never smokers, 1483 current smokers, 380 former smokers who quit 1 to 12 months before diagnosis, and 1719 former smokers who quit >12 months before diagnosis. Among patients with stage I, II, and III disease, only never smokers had better survival than current smokers (hazard ratio, 0.47 [95% confidence interval, 0.26‐0.85] vs 0.51 [95% confidence interval, 0.38‐0.68], respectively). Among patients with stage IV disease, the impact of smoking depended on age: Among younger patients (aged ≤55 years), being a never smoker and a former smoker for ≥12 months increased survival. After age 85 years, smoking status did not have a significant impact on overall survival. CONCLUSIONS: Patients who were smoking at the time of diagnosis had worse survival compared with never smokers. Among younger patients with stage IV disease, current smokers also had worse survival compared with former smokers who quit >12 months before diagnosis. It is likely that tumor biology plays a major role in the differences observed; however, to improve survival, it is prudent to encourage all smokers to quit smoking if they are diagnosed with NSCLC. Cancer 2013. © 2012 American Cancer Society. Patients who are smoking at the time of diagnosis have worse survival compared with never smokers. Although some of these differences probably are related to tumor biology, to improve survival, it is prudent to encourage all smokers to quit smoking if they are diagnosed with non–small cell lung cancer.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96341/1/27824_ftp.pd

    Coset Construction of Spin(7),G2Spin(7), G_2 Gravitational Instantons

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    We study Ricci-flat metrics on non-compact manifolds with the exceptional holonomy Spin(7),G2Spin(7), G_2. We concentrate on the metrics which are defined on R×G/H{\bf R} \times G/H. If the homogeneous coset spaces G/HG/H have weak G2G_2, SU(3) holonomy, the manifold R×G/H{\bf R} \times G/H may have Spin(7),G2Spin(7), G_2 holonomy metrics. Using the formulation with vector fields, we investigate the metrics with Spin(7)Spin(7) holonomy on R×Sp(2)/Sp(1),R×SU(3)/U(1){\bf R}\times Sp(2)/Sp(1), {\bf R}\times SU(3)/U(1). We have found the explicit volume-preserving vector fields on these manifold using the elementary coordinate parameterization. This construction is essentially dual to solving the generalized self-duality condition for spin connections. We present most general differential equations for each coset. Then, we develop the similar formulation in order to calculate metrics with G2G_2 holonomyComment: 29 pages, no figure; (v2) Errors are corrected ; (v3) Some explanations are added. More general differential equations for SU(3)/U(1) coset are give

    A Decolonial Critique of the Racialized “Localwashing” of Extraction in Central Africa

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    Responding to calls for increased attention to actions and reactions “from above” within the extractive industry, we offer a decolonial critique of the ways in which corporate entities and multinational institutions propagate racialized rhetoric of “local” suffering, “local” consultation, and “local” fault for failure in extractive zones. Such rhetoric functions to legitimize extractive intervention within a set of practices that we call localwashing. Drawing from a decade of research on and along the Chad-Cameroon Oil Pipeline, we show how multi-scalar actors converged to assert knowledge of, responsibility for, and collaborations with “local” people within a racialized politics of scale. These corporate representations of the racialized “local” are coded through long-standing colonial tropes. We identify three interrelated and overlapping flexian elite rhetoric(s) and practices of racialized localwashing: (a) anguishing, (b) arrogating, and (c) admonishing. These elite representations of a racialized “local” reveal diversionary efforts “from above” to manage public opinion, displace blame for project failures, and domesticate dissent in a context of persistent scrutiny and criticism from international and regional advocates and activists

    The High Energy Telescope for STEREO

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    The IMPACT investigation for the STEREO Mission includes a complement of Solar Energetic Particle instruments on each of the two STEREO spacecraft. Of these instruments, the High Energy Telescopes (HETs) provide the highest energy measurements. This paper describes the HETs in detail, including the scientific objectives, the sensors, the overall mechanical and electrical design, and the on-board software. The HETs are designed to measure the abundances and energy spectra of electrons, protons, He, and heavier nuclei up to Fe in interplanetary space. For protons and He that stop in the HET, the kinetic energy range corresponds to ∼13 to 40 MeV/n. Protons that do not stop in the telescope (referred to as penetrating protons) are measured up to ∼100 MeV/n, as are penetrating He. For stopping He, the individual isotopes 3He and 4He can be distinguished. Stopping electrons are measured in the energy range ∼0.7–6 MeV
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