1,084 research outputs found

    THE FEDERAL ROLE IN SMALL AREA PLANNING

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    Public Economics,

    Unusual behaviour of Dickey-Fuller tests in the presence of trend mis-specification

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    This paper analyses the properties of Dickey-Fuller (1979) (DF) unit root tests in the presence of trend mis-specification. It is shown that while the performance of the DF coefficient test is as expected, the DF test in its t-ratio form exhibits unusual behaviour. In particular it is found that the power of the test increases as the autoregressive parameter approaches 1. Interestingly, this increased power is not accompanied by oversizing.DF test

    Managing risk in cancer presentation, detection and referral: a qualitative study of primary care staff views

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    Objectives In the UK, there have been a number of national initiatives to promote earlier detection and prompt referral of patients presenting to primary care with signs and symptoms of cancer. The aim of the study was to explore the experiences of a range of primary care staff in promoting earlier presentation, detection and referral of patients with symptoms suggestive of cancer. Setting Six primary care practices in northwest England. Participants: 39 primary care staff from a variety of disciplines took part in five group and four individual interviews. Results The global theme to emerge from the interviews was ‘managing risk’, which had three underpinning organising themes: ‘complexity’, relating to uncertainty of cancer diagnoses, service fragmentation and plethora of guidelines; ‘continuity’, relating to relationships between practice staff and their patients and between primary and secondary care; ‘conflict’ relating to policy drivers and staff role boundaries. A key concern of staff was that policymakers and those implementing cancer initiatives did not fully understand how risk was managed within primary care. Conclusions Primary care staff expressed a range of views and opinions on the benefits of cancer initiatives. National initiatives did not appear to wholly resolve issues in managing risk for all practitioners. Staff were concerned about the number of guidelines and priorities they were expected to implement. These issues need to be considered by policymakers when developing and implementing new initiatives

    Theories for TC0 and Other Small Complexity Classes

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    We present a general method for introducing finitely axiomatizable "minimal" two-sorted theories for various subclasses of P (problems solvable in polynomial time). The two sorts are natural numbers and finite sets of natural numbers. The latter are essentially the finite binary strings, which provide a natural domain for defining the functions and sets in small complexity classes. We concentrate on the complexity class TC^0, whose problems are defined by uniform polynomial-size families of bounded-depth Boolean circuits with majority gates. We present an elegant theory VTC^0 in which the provably-total functions are those associated with TC^0, and then prove that VTC^0 is "isomorphic" to a different-looking single-sorted theory introduced by Johannsen and Pollet. The most technical part of the isomorphism proof is defining binary number multiplication in terms a bit-counting function, and showing how to formalize the proofs of its algebraic properties.Comment: 40 pages, Logical Methods in Computer Scienc

    A Tree-Ring-Based Reconstruction of Delaware River Basin Streamflow Using Hierarchical Bayesian Regression

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    A hierarchical Bayesian regression model is presented for reconstructing the average summer streamflow at five gauges in the Delaware River basin using eight regional tree-ring chronologies. The model provides estimates of the posterior probability distribution of each reconstructed streamflow series considering parameter uncertainty. The vectors of regression coefficients are modeled as draws from a common multivariate normal distribution with unknown parameters estimated as part of the analysis. This leads to a multilevel structure. The covariance structure of the streamflow residuals across sites is explicitly modeled. The resulting partial pooling of information across multiple stations leads to a reduction in parameter uncertainty. The effect of no pooling and full pooling of station information, as end points of the method, is explored. The no-pooling model considers independent estimation of the regression coefficients for each streamflow gauge with respect to each tree-ring chronology. The full-pooling model considers that the same regression coefficients apply across all streamflow sites for a particular tree-ring chronology. The cross-site correlation of residuals is modeled in all cases. Performance on metrics typically used by tree-ring reconstruction experts, such as reduction of error, coefficient of efficiency, and coverage rates under credible intervals is comparable to, or better, for the partial-pooling model relative to the no-pooling model, and streamflow estimation uncertainty is reduced. Long record simulations from reconstructions are used to develop estimates of the probability of duration and severity of droughts in the region. Analysis of monotonic trends in the reconstructed drought events do not reject the null hypothesis of no trend at the 90% significance over 1754–2000

    M Dwarfs from the SDSS, 2MASS and WISE Surveys: Identification, Characterisation and Unresolved Ultracool Companionship

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    The aim of this thesis is to use a cross-match between WISE, 2MASS and SDSS to identify a large sample of M dwarfs. Through the careful characterisation and quality control of these M dwarfs I aim to identify rare systems (i.e. unresolved UCD companions, young M dwarfs, late M dwarfs and M dwarfs with common proper motion companions). Locating ultracool companions to M dwarfs is important for constraining low-mass formation models, the measurement of substellar dynamical masses and radii, and for testing ultracool evolutionary models. This is done by using an optimised method for identifying M dwarfs which may have unresolved ultracool companions. To do this I construct a catalogue of 440 694 M dwarf candidates, from WISE, 2MASS and SDSS, based on optical- and near-infrared colours and reduced proper motion. With strict reddening, photometric and quality constraints I isolate a sub-sample of 36 898 M dwarfs and search for possible mid-infrared M dwarf + ultracool dwarf candidates by comparing M dwarfs which have similar optical/near-infrared colours (chosen for their sensitivity to effective temperature and metallicity). I present 1 082 M dwarf + ultracool dwarf candidates for follow-up. Using simulated ultracool dwarf companions to M dwarfs, I estimate that the occurrence of unresolved ultracool companions amongst my M dwarf + ultracool dwarf candidates should be at least four times the average for my full M dwarf catalogue. I discuss yields of candidates based on my simulations. The possible contamination and bias from misidentified M dwarfs is then discussed, from chance alignments with other M dwarfs and UCDs, from chance alignments with giant stars, from chance alignments with galaxies, and from blended systems (via visual inspection). I then use optical spectra from LAMOST to spectral type a subset of my M dwarf + ultracool dwarf candidates. These candidates need confirming as true M dwarf + ultracool dwarf systems thus I present a new method I developed to use low resolution near-infrared spectra which relies on two colour similar objects (one an excess candidate, one not) having very similar spectra. A spectral difference of these two colour similar objects should leave the signature of a UCD in the residual of their differences, which I look for using the difference in two spectral bands designed to identify UCD spectral features. I then present the methods used to identify other rare systems from my full M dwarf catalogue. Young M dwarfs were identified by measuring equivalent widths of Hα from the LAMOST spectra, and by measuring rotation periods from Kepler 2 light curves. I identify late M dwarfs photometrically (using reduced proper motion and colour cuts) and spectroscopically (using the LAMOST spectra with spectral indices from the literature). Also I present common proper motion analysis aimed at finding Tycho-2 primaries for my M dwarfs and look for physically separated M dwarf + M dwarf pairs (internally within my full M dwarf catalogue)

    Effects of Upstream Flood Protection on Land Use in the Upper Washita River Basin, Oklahoma

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    Agricultural Economic

    From public health to print: an interdisciplinary study of the presentation of cancer awareness messages in UK newspapers

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    National public health cancer awareness messages focus on raising awareness of cancer signs and symptoms and encouraging early diagnosis with the aim of increasing national cancer survival rates. While national and regional newspapers are key targets for message dissemination, evaluation documents and a scoping review identified that their representation in UK newspapers is under-researched, particularly in regional publications. The language of cancer, which is a contentious issue, has also not been explored. In response, this thesis makes an original contribution by examining how cancer awareness messages are reported in UK newspapers, and the reasons for this, within a public health context. An interdisciplinary, multiple methods analysis is presented consisting of: 1) a manifest content analysis of the presence of key cancer awareness messages, and the people featured in, 447 national and regional UK newspaper articles, 2) a corpus linguistic analysis of the articles’ language (specifically, word collocation, key words and key semantic domains), 3) a thematic analysis of fourteen semi-structured interviews with journalists and press officers. Integrated analysis was conducted using the ‘following a thread’ approach. Cancer awareness messages were lacking, even in articles that explicitly highlighted the awareness campaign. People featured tended to be unrepresentative of those most at risk of cancer. Cancer was often framed in terms of negative outcomes and unpleasant treatment. Battle metaphor was prevalent. Interviews suggested that newsworthiness factors and journalism norms are contributors to this, but that scope for change may be limited. Currently, UK newspaper reporting of cancer often does not reflect contemporary medical opinion, may skew public perceptions of risk and reinforce cancer fear. This may contribute to delayed diagnosis and, potentially, negatively influence survival rates. Future research is needed to test the assertions of this work but may also benefit from interdisciplinary collaborative efforts to improve approaches to public health message dissemination
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