2,698 research outputs found

    A computer aided teleoperator system Final report

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    Computer aided teleoperator system for remote handling task

    Event-Driven Network Programming

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    Software-defined networking (SDN) programs must simultaneously describe static forwarding behavior and dynamic updates in response to events. Event-driven updates are critical to get right, but difficult to implement correctly due to the high degree of concurrency in networks. Existing SDN platforms offer weak guarantees that can break application invariants, leading to problems such as dropped packets, degraded performance, security violations, etc. This paper introduces EVENT-DRIVEN CONSISTENT UPDATES that are guaranteed to preserve well-defined behaviors when transitioning between configurations in response to events. We propose NETWORK EVENT STRUCTURES (NESs) to model constraints on updates, such as which events can be enabled simultaneously and causal dependencies between events. We define an extension of the NetKAT language with mutable state, give semantics to stateful programs using NESs, and discuss provably-correct strategies for implementing NESs in SDNs. Finally, we evaluate our approach empirically, demonstrating that it gives well-defined consistency guarantees while avoiding expensive synchronization and packet buffering

    The Stability of Zirconia-Saturated Perovskite and Conditions in the Early Solar System

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    Perovskite and tazheranite (cubic zirconia) are among the most refractory oxides in nebular vapors [1] and important repositories for several refractory elements whose concentrations can potentially be used to constrain the environments of formation. There are numerous studies on the phase relations and thermodynamic properties of zirconias containing Al, Ca, Mg, Sc, Ti, and the REE [e.g., 2-4], but meteoritic zirconia is rare [5]. Meteoritic perovskite is much more common [e.g., 5-9], but there are few constraints on thermodynamic properties of the relevant solid solutions. Here, we describe experiments to determine the partitioning of minor elements between perovskite and zirconia of variable Zr/Ti; the results will be used to constrain thermodynamic modeling for the solid solutions represented by meteoritic perovskite

    Which patients are assessed by lung cancer nurse specialists? A national lung cancer audit study of over 128,000 patients across England

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    Background: Lung cancer nurse specialists (LCNS) are integral to the multidisciplinary clinical team, providing personalised physical and psycho-social interventions, and care management for people with lung cancer. The National Institute of Health and Care Excellence (NICE) recommend that all patients have access to a LCNS. We conducted a national study assessing whether there is variation in access to and timing of LCNS assessment. Methods: The National Cancer Action Team’s LCNS workforce census in England was linked with patient and hospital Trust data from the English National Lung Cancer Audit. Multivariate logistic regression was used to assess features associated with LCNS assessment. Results: 128,124 lung cancer patients were seen from 2007 to 2011. LCNS assessment confirmation was ‘yes’ in 62%, ‘no’ in 6% and ‘missing’ in 32%. Where (in clinic versus ward) and when (before versus after diagnosis) patients were assessed by a LCNS also varied. Older patients with poor performance status, early cancer stage, and comorbidities were less likely to be assessed; there was no difference with sex or socioeconomic group. Patients receiving any anti-cancer treatment were more likely to be assessed. Assessment was lower in Trusts with high annual patient numbers (odds ratio = 0.58, 95% confidence interval 0.37–0.91) and where LCNS caseload > 250 (0.69, 0.41–1.16, although not statistically significant), but increased where workload was conducted mostly by band 8 nurses (2.22, 1.22–4.02). Conclusion: LCNS assessment varied by patient and Trust features, which may indicate unmet need for some patients. The current workforce needs to expand as well as retain experienced LCNSs

    The Las Campanas IR Survey: Early Type Galaxy Progenitors Beyond Redshift One

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    (Abridged) We have identified a population of faint red galaxies from a 0.62 square degree region of the Las Campanas Infrared Survey whose properties are consistent with their being the progenitors of early-type galaxies. The optical and IR colors, number-magnitude relation and angular clustering together indicate modest evolution and increased star formation rates among the early-type field population at redshifts between one and two. The counts of red galaxies with HH magnitudes between 17 and 20 rise with a slope that is much steeper than that of the total H sample. The surface density of red galaxies drops from roughly 3000 per square degree at H = 20.5, I-H > 3 to ~ 20 per square degree at H = 20, I-H > 5. The V-I colors are approximately 1.5 magnitudes bluer on average than a pure old population and span a range of more than three magnitudes. The colors, and photometric redshifts derived from them, indicate that the red galaxies have redshift distributions adequately described by Gaussians with sigma_z ~ 0.2centerednearredshiftone,withtheexceptionthatgalaxieshaving centered near redshift one, with the exception that galaxies having V-I3$ are primarily in the 1.5 < z < 2 range. We find co-moving correlation lengths of 9-10 Mpc at z ~ 1, comparable to, or larger than, those found for early-type galaxies at lower redshifts. A simple photometric evolution model reproduces the counts of the red galaxies, with only a ~ 30% decline in the underlying space density of early-type galaxies at z ~ 1.2. We suggest on the basis of the colors, counts, and clustering that these red galaxies are the bulk of the progenitors of present day early-type galaxies.Comment: 5 pages, 3 figures, accepted for publication in the ApJ Letter

    Do working practices of cancer nurse specialists improve clinical outcomes? Retrospective cohort analysis from the English National Lung Cancer Audit

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    Background Cancer nurse specialists are advanced practitioners who offer continuity of care and expert support for people diagnosed with specific cancers. Health Education England's Cancer Workforce Plan prioritises expansion of cancer nurse specialist numbers by 2021 as part of the Cancer Taskforce Strategy for England. Objective To assess whether working practices of advanced practice specialist nurses are associated with clinical outcomes for people with lung cancer. Methods Adults with non-small cell lung cancer followed from 30 days post-diagnosis in English secondary care were obtained from the English National Lung Cancer Audit, 2007 to 2011. A national survey of lung cancer nurse specialists provided information on self-reported working practices. Mortality and unplanned admissions from 30 days to 12 months post diagnosis were respectively analysed using Cox and Poisson regression. Outcomes were assessed according to patients’ receipt of initial assessments by a lung cancer nurse specialist and according to trust-level reported working practices. Regression models were adjusted for individual sociodemographic and clinical characteristics, error adjusted for intracorrelations within regional cancer networks, and presented separately according to patients’ treatment pathways (surgery, chemotherapy, radiotherapy, or no anti-cancer therapy). Results Data for 108,115 people with lung cancer were analysed and associations with mortality and unplanned admissions were infrequent. Among people receiving only radiotherapy, however, the hazard for death was 17% lower among those who received an assessment by a lung cancer nurse specialist, compared with no assessment (hazard ratio = 0.83, 95% confidence interval 0.73–0.94; p = 0.003). The hazard was also lower among those receiving surgery (hazard ratio = 0.91, 0.84–0.99; p = 0.028). Among those receiving radiotherapy, nurse specialists’ reported confidence within multidisciplinary team settings was associated with a lower risk of death (hazard ratio = 0.88, 0.78–1.00; p = 0.049) and a lower rate of unplanned cancer-related admissions (incidence rate ratio = 0.83, 0.73–0.95; p = 0.007). Lung cancer nurse specialist assessments before/at diagnosis, were associated with a 5% lower rate of unplanned admissions, compared to when assessments occurred after diagnosis. Conclusion The contribution of nurse specialist working practices was occasionally associated with better outcomes for people with lung cancer. These were not limited to a single treatment pathway, but do indicate discrete relationships within pathways. Our study provides initial measures of overall lung cancer nurse specialist working practices at trusts, however, more detailed studies with longitudinal measurement of lung cancer nurse specialist-patient interaction are needed to better ascertain impacts on long-term patient outcomes. The findings highlight opportunities for potential improvement in effectiveness of service and care management

    The Las Campanas Infrared Survey. III. The H-band Imaging Survey and the Near-Infrared and Optical Photometric Catalogs

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    (Abridged) The Las Campanas Infrared Survey, based on broad-band optical and near-infrared photometry, is designed to robustly identify a statistically significant and representative sample of evolved galaxies at redshifts z>1. We have completed an H-band imaging survey over 1.1 square degrees of sky in six separate fields. The average 5 sigma detection limit in a four arcsecond diameter aperture is H ~ 20. Here we describe the design of the survey, the observation strategies, data reduction techniques, and object identification procedures. We present sample near-infrared and optical photometric catalogs for objects identified in two survey fields. We perform object detection in all bandpasses and identify ~ 54,000 galaxies over 1,408 square arcminutes of sky in the two fields. Of these galaxies, ~ 14,000 are detected in the H-band and ~ 2,000 have the colors of evolved galaxies, I - H >3, at z > 1. We find that (1) the differential number counts N(m) for the H-band detected objects has a slope of 0.44 at H 19. In addition, we find that (2) the differential number counts for the H detected red objects has a slope of 0.85 at H 20, with a mean surface density ~ 3,000 degree^{-2} mag^{-1} at H=20. Finally, we find that (3) galaxies with red optical to near-IR colors (I-H > 3) constitute ~ 20% of the H detected galaxies at H ~ 21, but only 2% at H = 19. We show that red galaxies are strongly clustered, which results in a strong field to field variation in their surface density. Comparisons of observations and predictions based on various formation scenarios indicate that these red galaxies are consistent with mildly evolving early-type galaxies at z ~ 1, although with a significant amount of on-going star formation as indicated by the large scatter in their V-I colors.Comment: 48 pages, 13 figures, accepted for publication in the Astrophysical Journa

    Tissintite, (Ca,Na,□)AlSi_2O_6: A Shock-Induced Clinopyroxene in the Tissint Meteorite

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    During a nanomineralogy investigation of the Tissint Martian meteorite, we discovered the new shock-induced mineral tissintite, (Ca,Na,□)AlSi_2O_6, which is named after Tissint, Morocco, where the host meteorite fell. This phase provides new insights into shock conditions and impact processes on Mars. Here, we emphasize the origin of tissintite (IMA 2013-027) and demonstrate how nanomineralogy can play an important role in meteorite and Mars rock research
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