726 research outputs found

    Cartography of high-dimensional flows: A visual guide to sections and slices

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    Symmetry reduction by the method of slices quotients the continuous symmetries of chaotic flows by replacing the original state space by a set of charts, each covering a neighborhood of a dynamically important class of solutions, qualitatively captured by a `template'. Together these charts provide an atlas of the symmetry-reduced `slice' of state space, charting the regions of the manifold explored by the trajectories of interest. Within the slice, relative equilibria reduce to equilibria and relative periodic orbits reduce to periodic orbits. Visualizations of these solutions and their unstable manifolds reveal their interrelations and the role they play in organizing turbulence/chaos.Comment: 12 Pages, 12 figure

    The Impact of a water-imposed interruption of growth in the Las Vegas region

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    This study is prompted by the expectation that water supplies for the Las Vegas Valley, both those used currently and those additional quantities available from existing sources, cannot sustain significant further economic growth of the region beyond the year 2006. There are five parts to this study. Part I uses a regional econometric (REMI) model to project the growth of the Las Vegas region to natural maturity, essentially unconstrained by an overriding water shortage. Part II is a reinforcing cross-section analysis of metropolitan areas in the United States to learn the most common natural growth patterns and those that have produced a good quality of life with a minimum of major local disturbances. This analysis gives attention to employment, population, income, and other key economic and social indicators. We give special attention to events in cities that are nearer to or at levels of maturity still many years away for Las Vegas. Part III of this study looks at the performance of sectors of the Las Vegas economy between 1970 and 1989. In particular, we identify those sectors of the Las Vegas economy that are sensitive to variations in growth, particularly during the 1979 to 1983 recession period. Part IV examines the impact of an unrelieved water shortage after 2006 on the Las Vegas socioeconomic future, giving special attention to the fraction of employment that depends on historically high growth rates to predict the impact of rapid decline of that employment. In Part IV, we employ the depth and power of the REMI model to portray the consequences for Las Vegas of a sharp drop in growth after 2006. In this part, we simulate a sixty percent reduction in construction employment, based on the experience of other cities investigated in Part II. We trace this disruption of growth through reduced employment, population, output, and income. We measure the effect of the water shortage by comparing the values of economic variables with a water shortage with a control forecast produced under the assumption of adequate water supplies. Part IV also includes a partial analysis of a Las Vegas water shortage on rural Nevada and on the state of Nevada as a whole. Part V investigates the impact on rural areas of construction and operation of a system bringing water from outlying areas to the Las Vegas region. We are aware that final planning for such a system is not yet completed. We have used a reasonable set of expenditures, locations, and periods that can be expected to occur. These simulations provide a plausible estimate of the effects of both the construction and operation of a water-delivery system on employment and income in those rural areas. As more definite information emerges, appropriate changes can readily be made and new analysis of impacts can be quickly provided

    Can programme theory be used as a 'translational tool’ to optimise health service delivery in a national early years’ initiative in Scotland: a case study

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    Background Theory-based evaluation (TBE) approaches are heralded as supporting formative evaluation by facilitating increased use of evaluative findings to guide programme improvement. It is essential that learning from programme implementation is better used to improve delivery and to inform other initiatives, if interventions are to be as effective as they have the potential to be. Nonetheless, few studies describe formative feedback methods, or report direct instrumental use of findings resulting from TBE. This paper uses the case of Scotland’s, National Health Service, early years’, oral health improvement initiative (Childsmile) to describe the use of TBE as a framework for providing feedback on delivery to programme staff and to assess its impact on programmatic action.<p></p> Methods In-depth, semi-structured interviews and focus groups with key stakeholders explored perceived deviations between the Childsmile programme 'as delivered’ and its Programme Theory (PT). The data was thematically analysed using constant comparative methods. Findings were shared with key programme stakeholders and discussions around likely impact and necessary actions were facilitated by the authors. Documentary review and ongoing observations of programme meetings were undertaken to assess the extent to which learning was acted upon.<p></p> Results On the whole, the activities documented in Childsmile’s PT were implemented as intended. This paper purposefully focuses on those activities where variation in delivery was evident. Differences resulted from the stage of roll-out reached and the flexibility given to individual NHS boards to tailor local implementation. Some adaptations were thought to have diverged from the central features of Childsmile’s PT, to the extent that there was a risk to achieving outcomes. The methods employed prompted national service improvement action, and proposals for local action by individual NHS boards to address this.<p></p> Conclusions The TBE approach provided a platform, to direct attention to areas of risk within a national health initiative, and to agree which intervention components were 'core’ to its hypothesised success. The study demonstrates that PT can be used as a 'translational tool’ to facilitate instrumental use of evaluative findings to optimise implementation within a complex health improvement programme.<p></p&gt

    Nonperturbative chemical modification of graphene for protein micropatterning

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    International audienceGraphene's extraordinary physical properties and its planar geometry make it an ideal candidate for a wide array of applications, many of which require controlled chemical modification and the spatial organization of molecules on its surface. In particular, the ability to functionalize and micropattern graphene with proteins is relevant to bioscience applications such as biomolecular sensors, single-cell sensors, and tissue engineering.Wereport a general strategy for the noncovalent chemical modification of epitaxial graphene for protein immobilization and micropatterning. We show that bifunctional molecule pyrenebutanoic acid-succinimidyl ester (PYR-NHS), composed of the hydrophobic pyrene and the reactive succinimide ester group, binds to graphene noncovalently but irreversibly. We investigate whether the chemical treatment perturbs the electronic band structure of graphene using X-ray photoemission (XPS) and Raman spectroscopy. Our results show that the sp2 hybridization remains intact and that the π band maintains its characteristic Lorentzian shape in the Raman spectra. The modified graphene surfaces, which bind specifically to amines in proteins, are micropatterned with arrays of fluorescently labeled proteins that are relevant to glucose sensors (glucose oxidase) and cell sensor and tissue engineering applications (laminin)

    Structural and Elite Features in Open Seat and Special U.S. House Elections: Is There a Sexual Bias?

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    Conventional wisdom long held that there was a bias against women in elections. Subsequent research indicates that men and women who challenge for elective office confront a common barrier: incumbency. In this article we extend our previous research on women in open seat elec tions by examining the performance of women who compete in special elections. Female candidate emergence in special House contests is slightly higher than in regular open seats. Using multivariate regression models, our analysis uncovered no bias against women in special elections. Over all, the performance of women in special elections and open seats indi cates that disruptions of the political status quo by the sudden vacancy creates opportunities that women exploit with effectiveness, although the low level of female candidate emergence limits the growth of descriptive female representation.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    Assessing the conservation value of waterbodies: the example of the Loire floodplain (France)

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    In recent decades, two of the main management tools used to stem biodiversity erosion have been biodiversity monitoring and the conservation of natural areas. However, socio-economic pressure means that it is not usually possible to preserve the entire landscape, and so the rational prioritisation of sites has become a crucial issue. In this context, and because floodplains are one of the most threatened ecosystems, we propose a statistical strategy for evaluating conservation value, and used it to prioritise 46 waterbodies in the Loire floodplain (France). We began by determining a synthetic conservation index of fish communities (Q) for each waterbody. This synthetic index includes a conservation status index, an origin index, a rarity index and a richness index. We divided the waterbodies into 6 clusters with distinct structures of the basic indices. One of these clusters, with high Q median value, indicated that 4 waterbodies are important for fish biodiversity conservation. Conversely, two clusters with low Q median values included 11 waterbodies where restoration is called for. The results picked out high connectivity levels and low abundance of aquatic vegetation as the two main environmental characteristics of waterbodies with high conservation value. In addition, assessing the biodiversity and conservation value of territories using our multi-index approach plus an a posteriori hierarchical classification methodology reveals two major interests: (i) a possible geographical extension and (ii) a multi-taxa adaptation

    Reliability of capturing foot parameters using digital scanning and the neutral suspension casting technique

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    <p>Abstract</p> <p>Background</p> <p>A clinical study was conducted to determine the intra and inter-rater reliability of digital scanning and the neutral suspension casting technique to measure six foot parameters. The neutral suspension casting technique is a commonly utilised method for obtaining a negative impression of the foot prior to orthotic fabrication. Digital scanning offers an alternative to the traditional plaster of Paris techniques.</p> <p>Methods</p> <p>Twenty one healthy participants volunteered to take part in the study. Six casts and six digital scans were obtained from each participant by two raters of differing clinical experience. The foot parameters chosen for investigation were cast length (mm), forefoot width (mm), rearfoot width (mm), medial arch height (mm), lateral arch height (mm) and forefoot to rearfoot alignment (degrees). Intraclass correlation coefficients (ICC) with 95% confidence intervals (CI) were calculated to determine the intra and inter-rater reliability. Measurement error was assessed through the calculation of the standard error of the measurement (SEM) and smallest real difference (SRD).</p> <p>Results</p> <p>ICC values for all foot parameters using digital scanning ranged between 0.81-0.99 for both intra and inter-rater reliability. For neutral suspension casting technique inter-rater reliability values ranged from 0.57-0.99 and intra-rater reliability values ranging from 0.36-0.99 for rater 1 and 0.49-0.99 for rater 2.</p> <p>Conclusions</p> <p>The findings of this study indicate that digital scanning is a reliable technique, irrespective of clinical experience, with reduced measurement variability in all foot parameters investigated when compared to neutral suspension casting.</p

    Supermassive black holes with high accretion rates in active galactic nuclei. XI. Accretion disk reverberation mapping of Mrk 142

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    Funding: KH acknowledges support from UK STFC grant ST/R00824/1.We performed an intensive accretion disk reverberation mapping campaign on the high accretion rate active galactic nucleus Mrk 142 in early 2019. Mrk 142 was monitored with the Neil Gehrels Swift Observatory for four months in X-rays and six different UV/optical filters. Ground-based photometric monitoring was obtained from the Las Cumbres Observatory, the Liverpool Telescope, and the Dan Zowada Memorial Observatory in ugriz filters, as well as from the Yunnan Astronomical Observatory in V. Mrk 142 was highly variable throughout, displaying correlated variability across all wavelengths. We measure significant time lags between the different wavelength lightcurves. In the UV and optical, we find that the wavelength-dependent lags, τ(λ), generally follow the relation τ(λ) ∝ λ 4/3, as expected for the T ∝ R −3/4 profile of a steady-state, optically thick, geometrically thin accretion disk, though they can also be fit by τ(λ) ∝ λ 2, as expected for a slim disk. The exceptions are the u and U bands, where an excess lag is observed, as has been observed in other active galactic nuclei and attributed to continuum emission arising in the broad-line region. Furthermore, we perform a flux–flux analysis to separate the constant and variable components of the spectral energy distribution, finding that the flux dependence of the variable component is consistent with the f ν  ∝ ν 1/3 spectrum expected for a geometrically thin accretion disk. Moreover, the X-ray to UV lag is significantly offset from an extrapolation of the UV/optical trend, with the X-rays showing a poorer correlation with the UV than the UV does with the optical. The magnitude of the UV/optical lags is consistent with a highly super-Eddington accretion rate.PostprintPeer reviewe
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