3,822 research outputs found

    Conceptual modelling of Work Systems using ABC notation

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    This paper seeks to extend the Work System Method WSM of Steven Alter by means of a modelling notation and mechanism called ABC. It does so because it is often necessary to know (or at least to conjecture) how things, processes and events interrelate. Our contention, which we support by literature primarily derived from cybernetics, is that we must discern conceptual models, so as to understand and, potentially, to improve by design, active models – specifically, the information systems which support work systems. We do this in order to regulate work systems, whether actively by explicit control or implicitly by aiding learning, understanding and self-control by modellers and participants. This paper is not a definitive statement concerning ABC. Instead, it sufficiently introduces the modelling approach to enable the reader to understand some examples of the approach as applied to work systems. It can also serve in a tutorial approach to the ABC modelling of work systems

    Prospects for Nonlinear Laser Diagnostics in the Jet Noise Laboratory

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    Two experiments were conducted to test whether optical methods, which rely on laser beam coherence, would be viable for off-body flow measurement in high-density, compressible-flow wind tunnels. These tests measured the effects of large, unsteady density gradients on laser diagnostics like laser-induced thermal acoustics (LITA). The first test was performed in the Low Speed Aeroacoustics Wind Tunnel (LSAWT) of NASA Langley Research Center's Jet Noise Laboratory (JNL). This flow facility consists of a dual-stream jet engine simulator (with electric heat and propane burners) exhausting into a simulated flight stream, reaching Mach numbers up to 0.32. A laser beam transited the LSAWT flow field and was imaged with a high-speed gated camera to measure beam steering and transverse mode distortion. A second, independent test was performed on a smaller laboratory jet (Mach number < 1.2 and mass flow rate < 0.1 kg/sec). In this test, time-averaged LITA velocimetry and thermometry were performed at the jet exit plane, where the effect of unsteady density gradients is observed on the LITA signal. Both experiments show that LITA (and other diagnostics relying on beam overlap or coherence) faces significant hurdles in the high-density, compressible, and turbulent flow environments similar to those of the JNL

    Human populations in the world's mountains: Spatio-temporal patterns and potential controls.

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    Changing climate and human demographics in the world's mountains will have increasingly profound environmental and societal consequences across all elevations. Quantifying current human populations in and near mountains is crucial to ensure that any interventions in these complex social-ecological systems are appropriately resourced, and that valuable ecosystems are effectively protected. However, comprehensive and reproducible analyses on this subject are lacking. Here, we develop and implement an open workflow to quantify the sensitivity of mountain population estimates over recent decades, both globally and for several sets of relevant reporting regions, to alternative input dataset combinations. Relationships between mean population density and several potential environmental covariates are also explored across elevational bands within individual mountain regions (i.e. "sub-mountain range scale"). Globally, mountain population estimates vary greatly-from 0.344 billion (31%) in 2015. A more detailed analysis using one of the population datasets (GHS-POP) revealed that in ∼35% of mountain sub-regions, population increased at least twofold over the 40-year period 1975-2015. The urban proportion of the total mountain population in 2015 ranged from 6% to 39%, depending on the combination of population and urban extent datasets used. At sub-mountain range scale, population density was found to be more strongly associated with climatic than with topographic and protected-area variables, and these relationships appear to have strengthened slightly over time. Such insights may contribute to improved predictions of future mountain population distributions under scenarios of future climatic and demographic change. Overall, our work emphasizes that irrespective of data choices, substantial human populations are likely to be directly affected by-and themselves affect-mountainous environmental and ecological change. It thereby further underlines the urgency with which the multitudinous challenges concerning the interactions between mountain climate and human societies under change must be tackled

    How can clinical research improve European health outcomes in cancer?

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    We review the mechanisms by which clinical cancer research can improve health outcomes and argue that this should be central to the development of policy. Recent series of major international studies have analysed large, often nationwide, datasets for cancer patient outcomes and participation in clinical research. They have evaluated and quantified the impact of new evidence generated by randomised controlled trials on cancer survival. They show a strong and probably causal relationship between the participation in clinical research in hospitals and the outcomes for patients with the disease under study in those hospitals. Also, institutions that are active in clinical trials appear to take up well evidenced innovations more rapidly than those which are not so engaged. Further work is necessary to confirm and examine the generalisability of these findings but we argue that all of these mechanisms are likely to lead to improved outcomes for patients as a consequence of the conduct of clinical research. The size of the benefit appears to be substantial and an active programme to promote clinical research across cancer care systems should be a part of National Cancer Plans and Cancer Control Strategies

    Supplemental Information For: Asymmetric Distribution of Lunar Impact Basins Caused by Variations in Target Properties

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    Maps of crustal thickness derived from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission revealed more large impact basins on the nearside hemisphere of the Moon than on its farside. The enrichment in heat-producing elements and prolonged volcanic activity on the lunar nearside hemisphere indicate that the temperature of the nearside crust and uppermantle was hotter than that of the farside at the time of basin formation. Using the iSALE-2D hydrocode to model impact basin formation, we found that impacts on the hotter nearside would have formed basins up to two times larger than similar impacts on the cooler farside hemisphere. The size distribution of lunar impact basins is thus not representative of the earliest inner Solar system impact bombardmen

    Asymmetric Distribution of Lunar Impact Basins Caused by Variations in Target Properties

    Get PDF
    Maps of crustal thickness derived from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission revealed more large impact basins on the nearside hemisphere of the Moon than on its farside. The enrichment in heat-producing elements and prolonged volcanic activity on the lunar nearside hemisphere indicate that the temperature of the nearside crust and upper mantle was hotter than that of the farside at the time of basin formation. Using the iSALE-2D hydrocode to model impact basin formation, we found that impacts on the hotter nearside would have formed basins up to two times larger than similar impacts on the cooler farside hemisphere. The size distribution of lunar impact basins is thus not representative of the earliest inner Solar system impact bombardment

    A Study of the Diverse T Dwarf Population Revealed by WISE

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    We report the discovery of 87 new T dwarfs uncovered with the Wide-field Infrared Survey Explorer (WISE) and three brown dwarfs with extremely red near-infrared colors that exhibit characteristics of both L and T dwarfs. Two of the new T dwarfs are likely binaries with L7+/-1 primaries and mid-type T secondaries. In addition, our follow-up program has confirmed 10 previously identified T dwarfs and four photometrically-selected L and T dwarf candidates in the literature. This sample, along with the previous WISE discoveries, triples the number of known brown dwarfs with spectral types later than T5. Using the WISE All-Sky Source Catalog we present updated color-color and color-type diagrams for all the WISE-discovered T and Y dwarfs. Near-infrared spectra of the new discoveries are presented, along with spectral classifications. To accommodate later T dwarfs we have modified the integrated flux method of determining spectral indices to instead use the median flux. Furthermore, a newly defined J-narrow index differentiates the early-type Y dwarfs from late-type T dwarfs based on the J-band continuum slope. The K/J indices for this expanded sample show that 32% of late-type T dwarfs have suppressed K-band flux and are blue relative to the spectral standards, while only 11% are redder than the standards. Comparison of the Y/J and K/J index to models suggests diverse atmospheric conditions and supports the possible re-emergence of clouds after the L/T transition. We also discuss peculiar brown dwarfs and candidates that were found not to be substellar, including two Young Stellar Objects and two Active Galactic Nuclei. The coolest WISE-discovered brown dwarfs are the closest of their type and will remain the only sample of their kind for many years to come.Comment: Accepted to ApJS on 15 January 2013; 99 pages in preprint format, 30 figures, 12 table

    Gravity Recovery and Interior Laboratory (GRAIL) Mission: Status at the Initiation of the Science Mapping Phase

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    The Gravity Recovery And Interior Laboratory (GRAIL) mission, a component of NASA's Discovery Program, launched successfully from Cape Canaveral Air Force Station on September 10, 2011. The dual spacecraft traversed independent, low-energy trajectories to the Moon via the EL-1 Lagrange point and inserted into elliptical, 11.5-hour polar orbits around the Moon on December 31, 2011, and January 1, 2012. The spacecraft are currently executing a series of maneuvers to circularize their orbits at 55-km mean altitude. Once the mapping orbit is achieved, the spacecraft will undergo additional maneuvers to align them into mapping configuration. The mission is on track to initiate the Science Phase on March 8, 2012

    Response comparison of multiple myeloma and monoclonal gammopathy of undetermined significance to the same anti-myeloma therapy: a retrospective cohort study

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    BackgroundMultiple myeloma is consistently preceded by monoclonal gammopathy of undetermined significance (MGUS), which is usually only treated by a form of anti-multiple myeloma therapy if it is causing substantial disease through deposition of secreted M proteins. However, studies comparing how MGUS and multiple myeloma plasma cell clones respond to these therapies are scarce. Biclonal gammopathy multiple myeloma is characterised by the coexistence of an active multiple myeloma clone and a benign MGUS clone, and thus provides a unique model to assess the responses of separate clones to the same anti-multiple myeloma therapy, in the same patient, at the same time. We aimed to identify how MGUS and multiple myeloma plasma cell clones responded to anti-multiple myeloma therapy in patients newly diagnosed with biclonal gammopathy multiple myeloma.MethodsIn this retrospective cohort study, we identified patients with biclonal gammopathy multiple myeloma by central laboratory analysis of 6399 newly diagnosed patients with multiple myeloma enrolled in three UK clinical trials (Myeloma IX, Myeloma XI, and TEAMM) between July 7, 2004, and June 2, 2015. In addition to the inclusion criteria of these trials, our study necessitated at trial entry the presence of two distinct M proteins in immunofixation electrophoresis. The primary endpoint was difference in response achieved with anti-multiple myeloma therapy on MGUS (which we defined as M2) and multiple myeloma (M1) clones—overall, within patients, and between therapy types—with international therapy response criteria assessed with χ2 analyses. We analysed by intention to treat.Findings44 patients with biclonal gammopathy multiple myeloma with IgG or IgA MGUS clones were subsequently identified from the three trials and then longitudinally monitored. 41 (93%) of M1 clones had a response to therapy (either complete response, very good partial response, partial response, or minor response) compared with only 28 (64%) of M2 clones (p=0·0010). For the 20 patients who received intensive therapy, there was no difference between the proportion of responding clones in M1 (19 [95%]) and M2 (15 [75%], p=0·13). However, for the 17 patients who received non-intensive therapy, 16 (94%) of M1 clones had a response compared with ten [59%] of M2 clones (p=0·031). When examining clones within the same patient, 30 (68%) of 44 individual patients had different levels of responses within the M1 and M2 clones. One patient exhibited M2 progression to myeloma and subsequently died.InterpretationThese results show that, in patients with biclonal gammopathy multiple myeloma, anti-multiple myeloma therapies exert a greater depth of response against multiple myeloma plasma cell clones than MGUS plasma cell clones. Although some MGUS clones exhibited a complete response, many did not respond, which suggests that the underlying features that render multiple myeloma plasma cells susceptible to therapy are present in only some MGUS plasma cell clones. To determine MGUS clone susceptibly to therapy, future studies might seek to identify, with biclonal gammopathy multiple myeloma as an investigative model, the genetic and epigenetic alterations that affect whether MGUS plasma cell clones are responsive to anti-multiple myeloma therapy
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