bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics of the large-scale circulation in high-Prandtl-number turbulent thermal convection
Authors: Xie Yi-Chao , Wei Ping , Xia Ke-Qing 
Published: February 2013

AbstractWe report experimental investigations of the dynamics of the large-scale circulation (LSC) in turbulent Rayleigh–Bénard convection at high Prandtl number $\mathit{Pr}= 19. 4$ (and also $\mathit{Pr}= 7. 8$) and Rayleigh number $\mathit{Ra}$ varying from $8. 3\times 1{0}^{8} $ to $2. 9\times 1{0}^{11} $ in a cylindrical convection cell with aspect ratio unity. The dynamics of the LSC is measured using the multithermal probe technique. Both the sinusoidal-fitting (SF) and the temperature-extrema-extraction (TEE) methods are used to analyse the properties of the LSC. It is found that the LSC in high-$\mathit{Pr}$ regime remains a single-roll structure. The azimuthal motion of the LSC is a diffusive process, which is the same as those for $\mathit{Pr}$ around 1. However, the azimuthal diffusion of the LSC, characterized by the angular speed $\Omega $ is almost two orders of magnitude smaller when compared with that in water. The non-dimensional time-averaged amplitude of the angular speed $\langle \vert \Omega \vert \rangle {T}_{d} $ (${T}_{d} = {L}^{2} / \kappa $ is the thermal diffusion time) of the LSC at the mid-height of the convection cell increases with $\mathit{Ra}$ as a power law, which is $\langle \vert \Omega \vert \rangle {T}_{d} \propto {\mathit{Ra}}^{0. 36\pm 0. 01} $. The $\mathit{Re}$ number based on the oscillation frequency of the LSC is found to scale with $\mathit{Ra}$ as $\mathit{Re}= 0. 13{\mathit{Ra}}^{0. 43\pm 0. 01} $. It is also found that the normalized flow strength $\langle \delta \rangle / \mrm{\Delta} T\times \mathit{Ra}/ \mathit{Pr}\propto {\mathit{Re}}^{1. 5\pm 0. 1} $, with the exponent in good agreement with that predicted by Brown & Ahlers (Phys. Fluids, vol. 20, 2008, p. 075101). A wealth of dynamical features of the LSC, such as the cessations, flow reversals, flow mode transitions, torsional and sloshing oscillations are observed in the high-$\mathit{Pr}$ regime as well.
On the measurement of the turbulent diffusivity of a large-scale magnetic field
Authors: Tobias S. M. , Cattaneo F. 
Published: February 2013

AbstractWe argue that a method developed by Ångström (Ann. Phys. Chem., vol. 114, 1861, pp. 513–530) to measure the thermal conductivity of solids can be adapted to determine the effective diffusivity of a large-scale magnetic field in a turbulent electrically conducting fluid. The method consists of applying an oscillatory source and measuring the steady-state response. We illustrate this method in a two-dimensional system. This geometry is chosen because it is possible to compare the results with independent methods that are restricted to two-dimensional flows. We describe two variants of this method: one (the ‘turbulent Ångström method’) that is better suited to laboratory experiments and a second (the ‘method of oscillatory sines’) that is effective for numerical experiments. We show that, if correctly implemented, all methods agree. Based on these results we argue that these methods can be extended to three-dimensional numerical simulations and laboratory experiments.
Distributed lock-in drives broadband vortex-induced vibrations of a long flexible cylinder in shear flow
Authors: Bourguet Rémi , Karniadakis George Em , Triantafyllou Michael S. 
Published: February 2013

AbstractA slender flexible body immersed in sheared cross-flow may exhibit vortex-induced vibrations (VIVs) involving a wide range of excited frequencies and structural wavenumbers. The mechanisms of broadband VIVs of a cylindrical tensioned beam of length-to-diameter aspect ratio 200 placed in shear flow, with an exponentially varying profile along the span, are investigated by means of direct numerical simulation. The Reynolds number is equal to 330 based on the maximum velocity, for comparison with previous work on narrowband vibrations in linear shear flow. The flow is found to excite the structure at a number of different locations under a condition of wake–body synchronization, or lock-in. Broadband responses are associated with a distributed occurrence of the lock-in condition along the span, as opposed to the localized lock-in regions limited to the high inflow velocity zone, reported for narrowband vibrations in sheared current. Despite the instantaneously multi-frequency nature of broadband responses, the lock-in phenomenon remains a locally mono-frequency event, since the vortex formation is generally synchronized with a single vibration frequency at a given location. The spanwise distribution of the excitation zones induces travelling structural waves moving in both directions; this contrasts with the narrowband case where the direction of propagation toward decreasing inflow velocity is preferred. A generalization of the mechanism of phase-locking between the in-line and cross-flow responses is proposed for broadband VIVs under the lock-in condition. A spanwise drift of the in-line/cross-flow phase difference is identified for the high-wavenumber vibration components; this drift is related to the strong travelling wave character of the corresponding structural waves.
The effect of velocity shear on dynamo action due to rotating convection
Authors: Hughes D. W. , Proctor M. R. E. 
Published: February 2013

AbstractRecent numerical simulations of dynamo action resulting from rotating convection have revealed some serious problems in applying the standard picture of mean field electrodynamics at high values of the magnetic Reynolds number, and have thereby underlined the difficulties in large-scale magnetic field generation in this regime. Here we consider kinematic dynamo processes in a rotating convective layer of Boussinesq fluid with the additional influence of a large-scale horizontal velocity shear. Incorporating the shear flow enhances the dynamo growth rate and also leads to the generation of significant magnetic fields on large scales. By the technique of spectral filtering, we analyse the modes in the velocity that are principally responsible for dynamo action, and show that the magnetic field resulting from the full flow relies crucially on a range of scales in the velocity field. Filtering the flow to provide a true separation of scales between the shear and the convective flow also leads to dynamo action; however, the magnetic field in this case has a very different structure from that generated by the full velocity field. We also show that the nature of the dynamo action is broadly similar irrespective of whether the flow in the absence of shear can support dynamo action.
Convectons in a rotating fluid layer
Authors: Beaume Cédric , Bergeon Alain , Kao Hsien-Ching , Knobloch Edgar 
Published: February 2013

AbstractTwo-dimensional convection in a plane layer bounded by stress-free perfectly conducting horizontal boundaries and rotating uniformly about the vertical is considered. Time-independent spatially localized structures, called convectons, of even and odd parity are computed. The convectons are embedded within a self-generated shear layer with a compensating shear flow outside the structure. These states are organized within a bifurcation structure called slanted snaking and may be present even when periodic convection sets in supercritically. These interesting properties are traced to the presence of a conserved quantity and hence to the use of stress-free boundary conditions.
A new equation describing travelling water waves
Authors: Oliveras Katie , Vasan Vishal 
Published: February 2013

AbstractA new single equation for the surface elevation of a travelling water wave in an incompressible, inviscid, irrotational fluid is derived. This new equation is derived without approximation from Euler’s equations, valid for both a one- and two-dimensional travelling-wave surface. We show that this new formulation can be used to efficiently derive higher-order Stokes-wave approximations, and pose that this new formulation provides a useful framework for further investigation of travelling water waves.
Hybrid Eulerian–Lagrangian simulations for polymer–turbulence interactions
Authors: Watanabe Takeshi , Gotoh Toshiyuki 
Published: February 2013

AbstractThe effects of polymer additives on decaying isotropic turbulence are numerically investigated using a hybrid approach consisting of Brownian dynamics simulations for an enormous number of dumbbells (of the order of 10 billion,$O(1{0}^{10} )$) and direct numerical simulations of turbulence making full use of large-scale parallel computations. Reduction of the energy dissipation rate and modification of the kinetic energy spectrum in the dissipation range scale were observed when the reaction term due to the polymer additives was incorporated into the equation of motion for the solvent fluid. An increase in the polymer concentration or Weissenberg number${W}_{i} $yielded significant modifications of the turbulence statistics at small scales, such as a suppression of the local energy dissipation fluctuations. A power-law decay of the kinetic energy spectrum$E(k, t)\sim {k}^{- 4. 7} $was observed in the wavenumber range below the Kolmogorov length scale when${W}_{i} = 25$. The generation of intense vortices was suppressed by the polymer additives, consistent with previous studies using the constitutive equations. The field structures of the trace of the polymer stress depended on the intensity of its fluctuation: sheet-like structures were observed for the intermediate intensity region and filamentary structures were observed for the intense region. The results obtained with few polymers and large replicas could approximate those with many polymers and smaller replicas as far as the large-scale statistics were concerned.
Minimal models for precipitating turbulent convection
Authors: Hernandez-Duenas Gerardo , Majda Andrew J. , Smith Leslie M. , Stechmann Samuel N. 
Published: February 2013

AbstractSimulations of precipitating convection would typically use a non-Boussinesq dynamical core such as the anelastic equations, and would incorporate water substance in all of its phases: vapour, liquid and ice. Furthermore, the liquid water phase would be separated into cloud water (small droplets suspended in air) and rain water (larger droplets that fall). Depending on environmental conditions, the moist convection may organize itself on multiple length and time scales. Here we investigate the question, what is the minimal representation of water substance and dynamics that still reproduces the basic regimes of turbulent convective organization? The simplified models investigated here use a Boussinesq atmosphere with bulk cloud physics involving equations for water vapour and rain water only. As a first test of the minimal models, we investigate organization or lack thereof on relatively small length scales of approximately 100 km and time scales of a few days. It is demonstrated that the minimal models produce either unorganized (‘scattered’) or organized convection in appropriate environmental conditions, depending on the environmental wind shear. For the case of organized convection, the models qualitatively capture features of propagating squall lines that are observed in nature and in more comprehensive cloud resolving models, such as tilted rain water profiles, low-altitude cold pools and propagation speed corresponding to the maximum of the horizontally averaged, horizontal velocity.
Mineral Waters, Electricity, and Hemlock: Devising Therapeutics for Children in Eighteenth-Century Institutions
Authors: MATHISEN ASHLEY 
Published: February 2013

AbstractThe development of paediatric medicine as a formal field of medical specialisation is usually traced to the mid-nineteenth century at the earliest. While it is true that formal specialisation in children’s medicine was not, on the whole, typical for eighteenth-century medical practitioners, many displayed a deep and lasting interest in the diseases of children, and were consequently eager to develop therapeutic practices which could be targeted at infants and children. This led to a variety of attempts at innovation, many of which benefitted from the co-operation of, and opportunities afforded by, institutions. By examining the efforts of several medical practitioners at the London Foundling Hospital and at the Dispensary for the Infant Poor, this article explores how eighteenth-century medical practitioners used their affiliations with institutions to address the problems of devising or adapting therapeutic practices and treatments for children. In tailoring medical practice to suit children and, more specifically, in using institutions to do so, medical practitioners were demonstrating that child patients required special consideration, that children’s diseases could be managed medically and with the benefit of new approaches and methods, and that children’s health, as a whole, was the province of medical practitioners.
‘For the Convenience and Comfort of the Persons Employed by them’: The Lowell Corporation Hospital, 1840–1930
Authors: Greenlees Janet 
Published: February 2013

AbstractThe first industrial hospital in America opened in 1840 in Lowell, Massachusetts. The Lowell Corporation Hospital was sponsored by the town’s textile employers for ninety years. This article analyses the contextual complications surrounding the employers’ sustained funding of the hospital. Motivations for sustained sponsorship included paternalism, clinical excellence, business custom, the labour situation in Lowell, civic duty and the political advantages of paternalism. By analysing the changing local context of the hospital, this article argues that a broader, more integrated approach to healthcare histories and institution histories is needed if we are to fully understand the myriad of healthcare providers and their local and national importance.
‘I’ve Never Found Doctors to be a Difficult Bunch’: Doctors, Managers and NHS Reorganisations in Manchester and Salford, 1948–2007
Authors: Snow Stephanie J. 
Published: February 2013

AbstractSince 1974 the National Health Service (NHS) has been subject to successive reorganisations which have shaped and reshaped patterns of administration, clinical care and services. This paper uses two sources of oral evidence: a Witness Seminar with a group of administrators who attended the NHS National Administrators’ Training Scheme in the late 1950s and a collection of interviews with doctors and managers who have played key roles in the health services of Manchester and Salford between 1974 and 2007. It surveys the day-to-day interactions between doctors and administrators/managers in hospital settings and analyses what these reveal about relationships within the broader context of shifting organisational structures and management styles. It suggests that the evidence challenges the historical stereotyping of the two groups and that strong working relationships have been determined as much by the values of respect and association as by changes to structures or management styles.
Road Traffic Injuries: Social Change and Development
Authors: Borowy Iris 
Published: February 2013

AbstractIn the course of the twentieth century road traffic injuries (RTIs) became a major public health burden. RTI deaths first increased in high-income countries and declined after the 1970s, and they soared in low- and middle-income countries from the 1980s onwards. As motorisation took off in North America and then spread to Europe and to the rest of the world discussions on RTIs have reflected and influenced international interpretations of the costs and benefits of ‘development’, as conventionally understood. Using discourse analysis, this paper explores how RTIs have been constructed in ways that have served regional and global development agendas and how ‘development’ has been (re-)negotiated through the discourse of RTIs and vice versa. For this purpose, this paper analyses a selection of key publications of organisations in charge of international health or transport and places them in the context of (a) the surrounding scientific discussion of the period and (b) of relevant data regarding RTI mortality, development funding, and road and other transport infrastructure. Findings suggest that constructions of RTIs have shifted from being a necessary price to be paid for development to being a sign of development at an early stage or of an insufficiently coordinated development. In recent years, RTI discussions have raised questions about development being misdirected and in need of fundamental rethinking. At present, discussions are believed to be at a crossroads between different evaluations of developmental conceptualisations for the future.
Modulation of platelet aggregation-related eicosanoid production by dietary F-fucoidan from brown algaLaminaria japonicain human subjects
Authors: Ren Rendong , Azuma Yosuke , Ojima Takao , Hashimoto Takashi , Mizuno Masashi , Nishitani Yosuke , Yoshida Masaru , Azuma Takeshi , Kanazawa Kazuki 
Published: February 2013

Laminaria japonicais traditionally eaten in Japan as a beneficial food for thrombosis. The alga contains two specific ingredients, a xanthophyll fucoxanthin (FX) and a polysaccharide, F-fucoidan (FD). The aim of the present study was to investigate whether FX or FD exhibited anti-thrombotic effects. For this purpose, three types of capsules, containing 1 mg FX, 400 mg fucoidan, and both, were prepared from the alga and administered to volunteers for 5 weeks. The dose of FD or FD+FX significantly shortened lysis time (LT) of the thrombus measured by a global thrombosis test in the blood, but FX did not. Examining the mechanism, dietary FD increased H2O2and the secretion of prostacyclin (PGI2), a potent inhibitor of platelet aggregation, in the blood, although FD was under the detection limit in the blood, determining with its monoclonal antibody. Furthermore, in mouse experiments, dietary FD was totally excreted into the faeces and was not incorporated into the blood. We then employed a co-culture system of a Caco-2 cell monolayer with fresh human blood. The addition of FD to Caco-2 cells stimulated the expression of NADPH oxidase 1 (NOX1) and dual oxidase 2 (DUOX2) mRNA and secreted H2O2onto the blood side accompanied by a significant increase in serum PGI2production. These effects were invalidated by the combined addition of FD with its monoclonal antibody. The results suggested that dietary FD stimulated the expression of H2O2-producing enzymes in intestinal epithelial cells and released H2O2into the blood, which played a signalling role to increase PGI2production and then shortened LT for thrombi.
ATTITUDES TO THE DISPLACEMENT OF CULTURAL PROPERTY IN THE WARS OF THE FRENCH REVOLUTION AND NAPOLEON
Authors: GILKS DAVID 
Published: February 2013

ABSTRACTThe French state expropriated an enormous quantity of cultural property from across Europe during the Wars of the Revolution and Napoleon, but much was returned in 1815 after the fall of the Empire. This article examines contemporary attitudes to the displacement of works of art, antiquities, scientific specimens, and rare books. The seizures were controversial: since they occurred at a time when plundering the vanquished was already considered questionable behaviour, they attracted opposition and needed to be justified. The article identifies the resulting repertoire of attitudes, arguing that this repertoire evolved with changing circumstances and was more varied than hitherto maintained. By situating this repertoire in a larger historical context, the article also reassesses the extent to which attitudes were derivative and innovative. It contends that the disputation as a whole did not amount to a decisive rupture in the treatment of foreign cultural property during wartime, but that it was nevertheless remarkable in two respects: concepts from hitherto unrelated subjects were applied to considerations about cultural property; and the perceived conditions under which cultural property could be legitimately transferred were revised.
FRENCH PRISONERS OF WAR, CONFLICTS OF HONOUR, AND SOCIAL INVERSIONS IN ENGLAND, 1744–1783
Authors: MORIEUX RENAUD 
Published: February 2013

ABSTRACTDuring the wars of the eighteenth century, French prisoners on parole in Britain were placed in a paradoxical situation of captives with privileges. Instead of studying these men as if they dwelt in a world apart, this article focuses on captivity zones as a social laboratory, where people of different status would socialize. These spaces accordingly provide a lens through which to glimpse the repercussions of international conflicts at the level of local communities. The disputes which opposed these captives to the English population, which were the object of letters of complaints sent by the French prisoners to the authorities, shed light on the normative and moral resources which were used by eighteenth-century Englishmen and Frenchmen to legitimize themselves in situations of social conflict. As a configuration characterized by shifting social relations, the parole zone brought together local, national, and international issues, intertwined primarily in the rhetoric of honour. In these incidents, there was no systematic alignment of class and national discourses and actions, while the precise standing of these Frenchmen on the social ladder was constantly challenged and debated. The resulting quarrels therefore reveal a series of social inversions: dominant groups in France were in many respects dominated in England. Rather than being a mere reflection of pre-existing social hierarchies, such micro-incidents reinvented them.
Corporate Criminal Responsibility: A Comparative Analysis
Authors: Nwafor Anthony O 
Published: February 2013

AbstractThis article focuses on the extent of a company's responsibility for the criminal conduct of its employees. It considers the initial reluctance of common law courts to hold corporations criminally responsible for offences requiring mens rea, a mental element not found in artificial persons. The courts overcame this initial difficulty with recourse to the identification doctrine, which seeks to attribute to a company the fault of certain of its officers. However, the restrictiveness and inconsistencies embodied in the various judicial statements of that doctrine precipitated recourse in some jurisdictions to civil law concepts, such as respondeat superior, vicarious liability and even strict liability, to found corporate criminal responsibility. The need to streamline the scope of, if not enhance, corporate criminal liability, has engendered statutory reforms in some jurisdictions. The article considers reforms in Australia, the UK, Canada and the USA, in comparison with the situation in South Africa and Lesotho.
Effects of chronic noise exposure on speech-in-noise perception in the presence of normal audiometry
Authors: Hope A J , Luxon L M , Bamiou D-E 
Published: February 2013

AbstractObjective:To assess auditory processing in noise-exposed subjects with normal audiograms and compare the findings with those of non-noise-exposed normal controls.Methods:Ten noise-exposed Royal Air Force aircrew pilots were compared with 10 Royal Air Force administrators who had no history of noise exposure. Participants were matched in terms of age and sex. The subjects were assessed in terms of: pure tone audiometry, transient evoked otoacoustic emissions, suppression of transient evoked otoacoustic emissions in contralateral noise and auditory processing task performance (i.e. masking, frequency discrimination, auditory attention and speech-in-noise).Results:All subjects had normal pure tone audiometry and transient evoked otoacoustic emissions amplitudes in both ears. The noise-exposed aircrew had similar pure tone audiometry thresholds to controls, but right ear transient evoked otoacoustic emissions were larger and speech-in-noise thresholds were elevated in the noise-exposed subjects compared to controls.Conclusion:The finding of poorer speech-in-noise perception may reflect noise-related impairment of auditory processing in retrocochlear pathways. Audiometry may not detect early, significant noise-induced hearing impairment.