46,718 research outputs found

    The letters of Charlotte Mary Yonge (1823-1901) edited by Charlotte Mitchell, Ellen Jordan and Helen Schinske.

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    Charlotte Yonge is one of the most influential and important of Victorian women writers; but study of her work has been handicapped by a tendency to patronise both her and her writing, by the vast number of her publications and by a shortage of information about her professional career. Scholars have had to depend mainly on the work of her first biographer, a loyal disciple, a situation which has long been felt to be unsatisfactory. We hope that this edition of her correspondence will provide for the first time a substantial foundation of facts for the study of her fiction, her historical and educational writing and her journalism, and help to illuminate her biography and also her significance in the cultural and religious history of the Victorian age

    Cardiovascular effects of variations in habitual levels of physical activity

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    Mechanisms involved in human cardiovascular adaption to stress, particularly adaption to different levels of physical activity are determined along with quantitative noninvasive methods for evaluation of cardiovascular function during stess in normal subjects and in individuals with latent or manifest cardiovascular disease. Results are summarized

    The1997 Scottish referendum : an analysis of the Scottish referendum

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    Referendums are rare events in the United Kingdom. Only one UK-wide referendum has been held - on membership of the European Community (as it then was) in 1975 - and before 1997 there had been only three other significant referendums: in 1973, in Northern Ireland, on the constitutional position of the province, and in 1979, in Scotland and Wales, on proposals for devolution. Thus the scarcity of cases available for study in itself makes the 1997 referendum on a Scottish parliament worthy of close attention. In addition, however, the fact that Scottish voters were asked to vote on, not one, but two questions - whether or not they were in favour of a Scottish parliament and whether such a parliament should have tax-varying powers - made the Scottish referendum unique among the (admittedly few) referendums that have been held in Britain

    Enhanced diffusion by reciprocal swimming

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    Purcell's scallop theorem states that swimmers deforming their shapes in a time-reversible manner ("reciprocal" motion) cannot swim. Using numerical simulations and theoretical calculations we show here that in a fluctuating environment, reciprocal swimmers undergo, on time scales larger than that of their rotational diffusion, diffusive dynamics with enhanced diffusivities, possibly by orders of magnitude, above normal translational diffusion. Reciprocal actuation does therefore lead to a significant advantage over non-motile behavior for small organisms such as marine bacteria

    Direct Collapse to Supermassive Black Hole Seeds with Radiation Transfer: Cosmological Halos

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    We have modeled direct collapse of a primordial gas within dark matter halos in the presence of radiative transfer, in high-resolution zoom-in simulations in a cosmological framework, down to the formation of the photosphere and the central object. Radiative transfer has been implemented in the flux-limited diffusion (FLD) approximation. Adiabatic models were run for comparison. We find that (a) the FLD flow forms an irregular central structure and does not exhibit fragmentation, contrary to adiabatic flow which forms a thick disk, driving a pair of spiral shocks, subject to Kelvin-Helmholtz shear instability forming fragments; (b) the growing central core in the FLD flow quickly reaches ~10 Mo and a highly variable luminosity of 10^{38}-10^{39} erg/s, comparable to the Eddington luminosity. It experiences massive recurrent outflows driven by radiation force and thermal pressure gradients, which mix with the accretion flow and transfer the angular momentum outwards; and (c) the interplay between these processes and a massive accretion, results in photosphere at ~10 AU. We conclude that in the FLD model (1) the central object exhibits dynamically insignificant rotation and slower than adiabatic temperature rise with density; (2) does not experience fragmentation leading to star formation, thus promoting the fast track formation of a supermassive black hole (SMBH) seed; (3) inclusion of radiation force leads to outflows, resulting in the mass accumulation within the central 10^{-3} pc, which is ~100 times larger than characteristic scale of star formation. The inclusion of radiative transfer reveals complex early stages of formation and growth of the central structure in the direct collapse scenario of SMBH seed formation.Comment: 19 pages, 16 figures, MNRAS, accepted for publicatio

    Effect of Patterned Slip on Micro and Nanofluidic Flows

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    We consider the flow of a Newtonian fluid in a nano or microchannel with walls that have patterned variations in slip length. We formulate a set of equations to describe the effects on an incompressible Newtonian flow of small variations in slip, and solve these equations for slow flows. We test these equations using molecular dynamics simulations of flow between two walls which have patterned variations in wettability. Good qualitative agreement and a reasonable degree of quantitative agreement is found between the theory and the molecular dynamics simulations. The results of both analyses show that patterned wettability can be used to induce complex variations in flow. Finally we discuss the implications of our results for the design of microfluidic mixers using slip.Comment: 13 pages, 12 figures, final version for publicatio

    Modern and ancient hiatuses in the pelagic caps of Pacific guyots and seamounts and internal tides

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    Incidences of non-deposition or erosion at the modern seabed and hiatuses within the pelagic caps of guyots and seamounts are evaluated along with paleo-temperature and physiographic information to speculate on the character of Late Cenozoic internal tidal waves in the upper Pacific Ocean. Drill core and seismic reflection data are used to classify sediment at the drill sites as having been either accumulating or eroding/nondepositing in the recent geological past. When those classified sites are compared against predictions of a numerical model of the modern internal tidal wave field (Simmons, 2008), the sites accumulating particles over the past few million years are found to lie away from beams of the modeled internal tide, while those that have not been accumulating are in internal tide beams. Given the correspondence to the modern internal wave field, we examine whether internal tides can explain ancient hiatuses at the drill sites. For example, Late Cenozoic pelagic caps on guyots among the Marshall Islands contain two hiatuses of broadly similar age, but the dates of the first pelagic sediments deposited following each hiatus do not correlate between guyots, suggesting that they originate not from ocean chemical changes but from physical processes, such as erosion by internal tidal waves. We investigate how changing conditions such as ocean temperature and basin physiography may have affected internal tides through the Cenozoic. Allowing for subsequent rotation or uplift by plate tectonics, ancient submarine ridges among the Solomon, Bonin and Marianas Island chains may have been responsible for some sediment hiatuses at these distant guyot sites

    Moneyball applied: Econometrics and the identification and recruitment of elite Australian footballers

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    The best selling book Moneyball posited a theory on the success of a Major League Baseball franchise that used detailed match data to identify inefficiencies in the market for professional baseball players. These statistics were then exploited to the advantage of that team. An important part of this strategy involved using mathematical techniques to identify which player statistics were most associated with team success, and then using these results to decide which players to recruit. This paper uses a similar approach to analyze elite Australian Football, making use of various types of regression models to identify and quantify the important player statistics in terms of their affect on match outcomes
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