White Rose Research Online

    Diet and ethnicity during the Viking colonisation of northern Scotland: evidence from fish bones and stable carbon isotopes

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    Diet and ethnicity are strongly related. Recent work on fish-bone ratios and stable carbon isotopes suggest that the Vikings increased the fish contribution to the diet of Orkney and Shetland by a greater investment in deep-sea fishing

    A note on state-space representations of locally stationary wavelet time series

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    In this note we show that the locally stationary wavelet process can be decomposed into a sum of signals, each of which follows a moving average process with time-varying parameters. We then show that such moving average processes are equivalent to state space models with stochastic design components. Using a simple simulation step, we propose a heuristic method of estimating the above state space models and then we apply the methodology to foreign exchange rates data

    Decoupling Dark Energy from Matter

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    We examine the embedding of dark energy in high energy models based upon supergravity and extend the usual phenomenological setting comprising an observable sector and a hidden supersymmetry breaking sector by including a third sector leading to the acceleration of the expansion of the universe. We find that gravitational constraints on the non-existence of a fifth force naturally imply that the dark energy sector must possess an approximate shift symmetry. When exact, the shift symmetry provides an example of a dark energy sector with a runaway potential and a nearly massless dark energy field whose coupling to matter is very weak, contrary to the usual lore that dark energy fields must couple strongly to matter and lead to gravitational inconsistencies. Moreover, the shape of the potential is stable under one-loop radiative corrections. When the shift symmetry is slightly broken by higher order terms in the Kähler potential, the coupling to matter remains small. However, the cosmological dynamics are largely affected by the shift symmetry breaking operators leading to the appearance of a minimum of the scalar potential such that dark energy behaves like an effective cosmological constant from very early on in the history of the universe

    Effect of longitudinal magnetic and density inhomogeneity on transversal coronal loop oscillations

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    Context. Observations of post-flare transversal coronal loop oscillations by TRACE have given us an excellent opportunity to implement magneto-seismological techniques for probing the plasma fine structure of the Sun's upper atmosphere. Aims. We investigate the combined effect of magnetic and density stratification on transversal coronal loop oscillations. Methods. A coronal loop will be modelled as an expanding magnetic flux tube with arbitrary longitudinal plasma density. The governing equation of the fast kink body mode is derived and solved by analytical approximation and numerical methods. Results. It is found that even a relatively small coronal loop expansion can have a significant and pronounced effect on the accuracy of the plasma density scale height measurements derived from observation of loop oscillations. Conclusions. To conduct more accurate and realistic magneto-seismology of coronal loops, the magnetic field divergence should be taken into account

    Discovery of spatial periodicities in a coronal loop using automated edge-tracking algorithms

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    A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. Applying this technique to TRACE data, obtained using the 171 Å filter on 1998 July 14, we detect a coronal loop undergoing a 270 s kink-mode oscillation, as previously found by Aschwanden et al. However, we also detect flare-induced, and previously unnoticed, spatial periodicities on a scale of 3500 km, which occur along the coronal loop edge. Furthermore, we establish a reduction in oscillatory power for these spatial periodicities of 45% over a 222 s interval. We relate the reduction in detected oscillatory power to the physical damping of these loop-top oscillations

    Interleukin-1 regulates multiple atherogenic mechanisms in response to fat feeding

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    Background: Atherosclerosis is an inflammatory process that develops in individuals with known risk factors that include hypertension and hyperlipidaemia, influenced by diet. However, the interplay between diet, inflammatory mechanisms and vascular risk factors requires further research. We hypothesised that interleukin-1 (IL-1) signaling in the vessel wall would raise arterial blood pressure and promote atheroma. Methodology/Principal Findings: Apoe(-/-) and Apoe(-/-)/IL-1R1(-/-) mice were fed high fat diets for 8 weeks, and their blood pressure and atherosclerosis development measured. Apoe(-/-)/IL-R1(-/-) mice had a reduced blood pressure and significantly less atheroma than Apoe(-/-) mice. Selective loss of IL-1 signaling in the vessel wall by bone marrow transplantation also reduced plaque burden (p<0.05). This was associated with an IL-1 mediated loss of endothelium-dependent relaxation and an increase in vessel wall Nox 4. Inhibition of IL-1 restored endothelium-dependent vasodilatation and reduced levels of arterial oxidative stress. Conclusions/Significance: The IL-1 cytokine system links atherogenic environmental stimuli with arterial inflammation, oxidative stress, increased blood pressure and atherosclerosis. This is the first demonstration that inhibition of a single cytokine can block the rise in blood pressure in response to an environmental stimulus. IL-1 inhibition may have profound beneficial effects on atherogenesis in man

    Speech Driven Environmental Control System (SPECS) From Specification to Prototype

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    The SPECS project is designing a new speech driven environmental control to include use by people with dysathric speech. The project is funded by the National Institute for Health Research and is developing the device with a large UK assistive technology company. The aim is that the device will be designed in a user-centric way. The initial stage of the project involved performing detailed qualitative interviews of people currently using speech-driven environmental control systems and a focus group of professionals which discussed current speech-driven environmental control systems and ‘blue sky’ ideas. Data from these were rigorously analysed using a framework approach [1]. This enabled full specification of the proposed new device and the results of this stage have recently been published [2]. This paper will present the process undertaken to go from specification to prototype testing, how user involvement has been incorporated and will discuss the key findings to date. At the time of RAATE 2009 we will be nearing completion of the prototype testing

    Speaking Through Silence: Conceptual Art and Conversational Implicature

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    I first try to identify what problem, if any conceptual art poses for philosophical aesthetics. It is harder than one might think to formulate some claim about traditional art with which much conceptual art is inconsistent. The idea that sense experience plays a special role in the appreciation of traditional artworks falls foul of literature. Instead I focus on the idea that conceptual art exhibits a particularly loose relation between the properties with which we engage in appreciating it and the properties on which those artistic properties depend. In Part II, I then offer an account of how conceptual art communicates, and attempt to use it to illuminate some prominent features of that art. I suggest it works by frustrating certain fundamental expectations with which we approach it. In this it is analogous to certain ways of indirectly communicating in conversation – certain kinds of conversational implicature. At the close, I ask whether this account allows us to address the problem identified in Part I

    Counting monomials

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    This paper presents two enumeration techniques based on Hilbert functions. The paper illustrates these techniques by solving two chessboard problems

    The support of top graded local cohomology modules

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    Let $R_0$ be any domain, let $R=R_0[U_1, ..., U_s]/I$, where $U_1, ..., U_s$ are indeterminates of some positive degrees, and $I\subset R_0[U_1, ..., U_s]$ is a homogeneous ideal. The main theorem in this paper is states that all the associated primes of $H:=H^s_{R_+}(R)$ contain a certain non-zero ideal $c(I)$ of $R_0$ called the ``content'' of $I$. It follows that the support of $H$ is simply $V(\content(I)R + R_+)$ (Corollary 1.8) and, in particular, $H$ vanishes if and only if $c(I)$ is the unit ideal. These results raise the question of whether local cohomology modules have finitely many minimal associated primes-- this paper provides further evidence in favour of such a result. Finally, we give a very short proof of a weak version of the monomial conjecture based on these results
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