bluuebunny/crossref_metadata_2025_split huggingface dataset:
Receptivity of the boundary layer to vibrations of the wing surface
Authors: Ruban A. I. , Bernots T. , Pryce D. 
Published: May 2013

AbstractIn this paper we study the generation of Tollmien–Schlichting waves in the boundary layer due to elastic vibrations of the wing surface. The subsonic flow regime is considered with the Mach number outside the boundary layer $M= O(1)$. The flow is investigated based on the asymptotic analysis of the Navier–Stokes equations at large values of the Reynolds number, $\mathit{Re}= {\rho }_{\infty } {V}_{\infty } L/ {\mu }_{\infty } $. Here $L$ denotes the wing section chord; and ${V}_{\infty } $, ${\rho }_{\infty } $ and ${\mu }_{\infty } $ are the free stream velocity, air density and dynamic viscosity, respectively. We assume that in the spectrum of the wing vibrations there is a harmonic that comes in to resonance with the Tollmien–Schlichting wave on the lower branch of the stability curve; this happens when the frequency of the harmonic is a quantity of the order of $({V}_{\infty } / L){\mathit{Re}}^{1/ 4} $. The wavelength, $\ell $, of the elastic vibrations of the wing is assumed to be $\ell \sim L{\mathit{Re}}^{- 1/ 8} $, which has been found to represent a ‘distinguished limit’ in the theory. Still, the results of the analysis are applicable for $\ell \gg L{\mathit{Re}}^{- 1/ 8} $ and $\ell \ll L{\mathit{Re}}^{- 1/ 8} $; the former includes an important case when $\ell = O(L)$. We found that the vibrations of the wing surface produce pressure perturbations in the flow outside the boundary layer, which can be calculated with the help of the ‘piston theory’, which remains valid provided that the Mach number, $M$, is large as compared to ${\mathit{Re}}^{- 1/ 4} $. As the pressure perturbations penetrate into the boundary layer, a Stokes layer forms on the wing surface; its thickness is estimated as a quantity of the order of ${\mathit{Re}}^{- 5/ 8} $. When $\ell = O({\mathit{Re}}^{- 1/ 8} )$ or $\ell \gg {\mathit{Re}}^{- 1/ 8} $, the solution in the Stokes layer appears to be influenced significantly by the compressibility of the flow. The Stokes layer on its own is incapable of producing the Tollmien–Schlichting waves. The reason is that the characteristic wavelength of the perturbation field in the Stokes layer is much larger than that of the Tollmien–Schlichting wave. However, the situation changes when the Stokes layer encounters a wall roughness, which are plentiful in real aerodynamic flows. If the longitudinal extent of the roughness is a quantity of the order of ${\mathit{Re}}^{- 3/ 8} $, then efficient generation of the Tollmien–Schlichting waves becomes possible. In this paper we restrict our attention to the case when the Stokes layer interacts with an isolated roughness. The flow near the roughness is described by the triple-deck theory. The solution of the triple-deck problem can be found in an analytic form. Our main concern is with the flow behaviour downstream of the roughness and, in particular, with the amplitude of the generated Tollmien–Schlichting waves.
Multilayer shallow water equations with complete Coriolis force. Part 3. Hyperbolicity and stability under shear
Authors: Stewart Andrew L. , Dellar Paul J. 
Published: May 2013

AbstractWe analyse the hyperbolicity of our multilayer shallow water equations that include the complete Coriolis force due to the Earth’s rotation. Shallow water theory represents flows in which the vertical shear is concentrated into vortex sheets between layers of uniform velocity. Such configurations are subject to Kelvin–Helmholtz instabilities, with arbitrarily large growth rates for sufficiently short-wavelength disturbances. These instabilities manifest themselves through a loss of hyperbolicity in the shallow water equations, rendering them ill-posed for the solution of initial value problems. We show that, in the limit of vanishingly small density difference between the two layers, our two-layer shallow water equations remain hyperbolic when the velocity difference remains below the same threshold that also ensures the hyperbolicity of the standard shallow water equations. Direct calculation of the domain of hyperbolicity becomes much less tractable for three or more layers, so we demonstrate numerically that the threshold for the velocity differences, below which the three-layer equations remain hyperbolic, is also unchanged by the inclusion of the complete Coriolis force. In all cases, the shape of the domain of hyperbolicity, which extends outside the threshold, changes considerably. The standard shallow water equations only lose hyperbolicity due to shear parallel to the direction of wave propagation, but the complete Coriolis force introduces another mechanism for loss of hyperbolicity due to shear in the perpendicular direction. We demonstrate that this additional mechanism corresponds to the onset of a transverse shear instability driven by the non-traditional components of the Coriolis force in a three-dimensional continuously stratified fluid.
Lagrangian approach to laminar–turbulent interfaces in transitional pipe flow
Authors: Holzner Markus , Song Baofang , Avila Marc , Hof Björn 
Published: May 2013

AbstractTransition in shear flows is characterized by localized turbulent regions embedded in the surrounding laminar flow. These so-called turbulent spots or puffs are observed in a variety of shear flows and in certain Reynolds-number regimes, and they are advected by the flow while keeping their characteristic length. We show here for the case of pipe flow that this seemingly passive advection of turbulent puffs involves continuous entrainment and relaminarization of laminar and turbulent fluid across strongly convoluted interfaces. Surprisingly, interface areas are almost two orders of magnitude larger than the pipe cross-section, while local entrainment velocities are much smaller than the mean speed. Even though these velocities were shown to be small and proportional to the Kolmogorov velocity scale (in agreement with a prediction by Corrsin) in a flow without mean shear before, we find that, in pipe flow, local entrainment velocities are about an order of magnitude smaller than this scale. The Lagrangian method used to study the dynamics of the laminar–turbulent interfaces allows accurate determination of the leading and trailing edge speeds. However, to resolve the highly complex interface dynamics requires much higher numerical resolutions than for ordinary turbulent flows. This method also reveals that the volume flux across the leading edge has the same radial dependence but the opposite sign as that across the trailing edge, and it is this symmetry that is responsible for the puff shape remaining constant.
Aerodynamic noise from a poroelastic edge with implications for the silent flight of owls
Authors: Jaworski Justin W. , Peake N. 
Published: May 2013

AbstractThe interaction of a turbulent eddy with a semi-infinite poroelastic edge is examined with respect to the effects of both elasticity and porosity on the efficiency of aerodynamic noise generation. The scattering problem is solved using the Wiener–Hopf technique to identify the scaling dependence of the resulting aerodynamic noise on plate and flow properties, including the dependence on a characteristic flow velocity$U$. Special attention is paid to the limiting cases of porous-rigid and impermeable–elastic plate conditions. Asymptotic analysis of these special cases reveals parametric limits where the far-field acoustic power scales like${U}^{6} $for a porous edge, and a new finite range of${U}^{7} $behaviour is found for an elastic edge, to be compared with the well-known${U}^{5} $dependence for a rigid impermeable edge. Further numerical results attempt to address how trailing-edge noise may be mitigated by porosity and flexibility and seek to deepen the understanding of how owls hunt in acoustic stealth.
Tracer particle momentum effects in vortex flows
Authors: Birch David M. , Martin Nicholas 
Published: May 2013

AbstractThe measurement of vortex flows with particle-image velocimetry (PIV) is particularly susceptible to error arising from the finite mass of the tracer particles, owing to the high velocities and accelerations typically experienced. A classical model of Stokes-flow particle transport is adopted, and an approximate solution for the case of particle transport within an axisymmetric, quasi-two-dimensional Batchelor$q$-vortex is presented. A generalized expression for the maximum particle tracking error is proposed for each of the velocity components, and the importance of finite particle size distributions is discussed. The results indicate that the tangential velocity component is significantly less sensitive to tracking error than the radial component, and that the conventional particle selection criterion (based on the particle Stokes number) may result in either over- or under-sized particles for a specified allowable error bound. Results were demonstrated by means of PIV measurements carried out in air and water using particles with very different properties.
Oral administration ofBifidobacterium longumCECT 7347 ameliorates gliadin-induced alterations in liver iron mobilisation
Authors: Laparra José Moisés , Olivares Marta , Sanz Yolanda 
Published: May 2013

Coeliac disease is an autoimmune disorder triggered by gluten intake, causing intestinal inflammation and mucosal damage commonly associated with the malabsorption of nutrients and ferropenic anaemia. The present study evaluates the effects of the oral administration ofBifidobacterium longumCECT 7347 on gliadin-mediated alterations in hepatic Fe deposition and Hb concentration, liver transferrin receptor (TfR)-2, IL-6, TNF-α and hepcidin (Hamp) expression (mRNA), and active hepcidin peptide production by liquid chromatography–MS/MS. Weanling rats, sensitised or not with interferon (IFN)-γ, were fed with gliadins and/or the bifidobacterial strain. Gliadin feeding increased hepatic Fe deposition; however, only gliadin-fed sensitised animals showed lower Hb concentrations than the controls.TfR2expression decreased after gliadins were fed to both sensitised and non-sensitised animals, and restored by the administration ofB. longum. These observations were accompanied by increases inIL-6expression levels in all the treatment groups; however,TNF-αexpression only increased significantly in animals fed gliadins alone or together withB. longumif they had previously been sensitised with IFN-γ. Liver expression levels ofHampdiminished in all cases to the lowest values in animals sensitised with IFN-γ after being fed with gliadins and/or bifidobacteria. In these animals, plasmaHampactive peptide concentrations significantly increased when compared with the controls. Significant correlations were calculated betweenHampexpression and liver Fe contents (liver Fe = 1/0·0032+0·032 × Hampexp), and Hb concentrations (Hb = 11·49+10·13 × (Hampexp)1/2). These data indicate that oral administration ofB. longumameliorates gliadin-mediated perturbations in liver Fe deposition and mobilisation.
Nostalgia for the Old Versus Wonder at the New: Cultural disenchantment and the temptation of modernity in Nie Hai Hua
Authors: ZHUANG GUO-OU 
Published: May 2013

AbstractThis paper attempts to revise aspects of the existing interpretations of Nie Hai Hua (A Flower in a Sinful Sea) by applying perspectives from post-colonial studies to the study of this late Qing Chinese novel. Here the novel is read as a national narrative that portrays the emergence of China as a modern nation state from a decaying empire, with its intelligentsia caught between their desire to embrace modernity and nostalgia for cultural traditions. From the mid-nineteenth century to the early twentieth century, traditional Chinese scholars were faced with a predicament: they were lured by the modernity represented by Western learning, on the one hand, but were tied by an emotional link to Chinese tradition, on the other. In a disintegrating society, they struggled both to preserve their own cultural identity and construct a new identity. The opposing groups of Chinese literati portrayed in the novel in fact reflect the schizophrenic state of the Chinese consciousness on the threshold of modernity.To write the story of the nation demands that we articulate that archaic ambivalence that informs modernity.1
Laser produced thin metallic planar mini-flyer generation using fiber optic plate
Authors: Shukla Mayank , Sawant Sachin , Agrawal Ashish , Kashyap Yogesh , Roy Tushar , Sinha Amar 
Published: May 2013

AbstractLaser produced planar mini flyer generation has widely gained importance owing to its wide ranging applications in the field of condensed matter, astrophysics, material research, shock phenomenon, etc. Flattop smooth laser beam profile as driver is the primary requirement for planar flyer generation besides special multilayered target geometry. We present here laser produced thin metallic planar mini-flyer generation using a fiber optic plate (FOP) of 8 mm thickness and about 6 µm fiber dimension. This technique is unique in the sense that it doesn't require large length as compared to optical fiber. A Gaussian shape laser beam from a laser oscillator was allowed to fall on the FOP generating a speckle pattern. This pattern was relayed and amplified using lenses and laser amplifiers to achieve energy of about 400 mJ. The beam was focused on a substrate (fused silica) based multilayered target on which flyer disks of different materials such as Al. Cu, Br, and Ta were attached. Velocities as high as 400 m/s was measured for Al flyer of 1.5 mm diameter and thickness 50 µm. Flyer disks were completely recovered after the laser shot. We also present a theoretical analysis along with experimental results of the laser beam smoothing technique using a He-Ne laser and FOP. Each channel of the FOP acts as a small single mode optical fiber. The basic idea was to divide the incoming coherent beam into many beam-lets introducing random distribution in length or/and diameter of optical fibers of FOP. The individual FOP channel acts as a diverging source because of single mode fiber with natural divergence λ/d. However, due to the small randomness in length or diameter, the individual diffraction sources are not in phase. This results in the generation of speckles in both near (Fresnel) and far field (Fraunhoffer) destroys the spatial coherence of the beam.
Contesting Food Safety in the Chinese Media: Between Hegemony and Counter-Hegemony
Authors: Yang Guobin 
Published: May 2013

AbstractFood safety is a matter of intense contestation in the Chinese media. Through three case studies, this article shows that government and corporate elites strive to maintain media hegemony while citizen-consumers and activists engage in counter-hegemonic practices. Under conditions of hegemony, citizen dissent is most likely to take one of two forms: diffused contention or radical protest. Like theyinandyangof civic dissent, these two forms are both the results of, and responses to, state and corporate hegemony.
Mycobacterium bovis (bovine tuberculosis) infection in North American wildlife: current status and opportunities for mitigation of risks of further infection in wildlife populations
Authors: MILLER R. S. , SWEENEY S. J. 
Published: May 2013

SUMMARYMycobacterium bovis (M. bovis), the causative agent of bovine tuberculosis, has been identified in nine geographically distinct wildlife populations in North America and Hawaii and is endemic in at least three populations, including members of the Bovidae, Cervidae, and Suidae families. The emergence of M. bovis in North American wildlife poses a serious and growing risk for livestock and human health and for the recreational hunting industry. Experience in many countries, including the USA and Canada, has shown that while M. bovis can be controlled when restricted to livestock species, it is almost impossible to eradicate once it has spread into ecosystems with free-ranging maintenance hosts. Therefore, preventing transmission of M. bovis to wildlife may be the most effective way to mitigate economic and health costs of this bacterial pathogen. Here we review the status of M. bovis infection in wildlife of North America and identify risks for its establishment in uninfected North American wildlife populations where eradication or control would be difficult and costly. We identified four common risk factors associated with establishment of M. bovis in uninfected wildlife populations in North America, (1) commingling of infected cattle with susceptible wildlife, (2) supplemental feeding of wildlife, (3) inadequate surveillance of at-risk wildlife, and (4) unrecognized emergence of alternate wildlife species as successful maintenance hosts. We then propose the use of integrated and adaptive disease management to mitigate these risk factors to prevent establishment of M. bovis in susceptible North American wildlife species.
Spatial variation in the risk of hospitalization with childhood pneumonia and empyema in the North of England
Authors: BLAIN A. P. , THOMAS M. F. , SHIRLEY M. D. F. , SIMMISTER C. , ELEMRAID M. A. , GORTON R. , PEARCE M. S. , CLARK J. E. , RUSHTON S. P. , SPENCER D. A. 
Published: May 2013

SUMMARYThe aim of this study was to investigate spatial variation in risk of hospitalization in childhood pneumonia and empyema in the North of England and associated risk factors. Data on childhood (0–14 years) hospital admissions with a diagnosis pneumonia or empyema were linked to postcode districts. Bayesian conditional autoregressive models were used to evaluate spatial variation and the relevance of specific spatial covariates in an area-based study using postcode as the areal unit. There was a sixfold variation in the risk of hospitalization due to pneumonia across the study region. Variation in risk was associated with material deprivation, Child Well-being Index (CWI) health domain score, number of children requiring local authority support, and distance to hospital. No significant spatial variation in risk for empyema was found.
Hospital antibiotic use and its relationship to age-adjusted comorbidity and alcohol-based hand rub consumption
Authors: ALDEYAB M. A. , McELNAY J. C. , SCOTT M. G. , ELHAJJI F. W. DARWISH , KEARNEY M. P. 
Published: May 2013

SUMMARYThe objective of this study was to evaluate the effect of age-adjusted comorbidity and alcohol-based hand rub on monthly hospital antibiotic usage, retrospectively. A multivariate autoregressive integrated moving average (ARIMA) model was built to relate the monthly use of all antibiotics grouped together with age-adjusted comorbidity and alcohol-based hand rub over a 5-year period (April 2005–March 2010). The results showed that monthly antibiotic use was positively related to the age-adjusted comorbidity index (concomitant effect, coefficient 1·103, P = 0·0002), and negatively related to the use of alcohol-based hand rub (2-month delay, coefficient −0·069, P = 0·0533). Alcohol-based hand rub is considered a modifiable factor and as such can be identified as a target for quality improvement programmes. Time-series analysis may provide a suitable methodology for identifying possible predictive variables that explain antibiotic use in healthcare settings. Future research should examine the relationship between infection control practices and antibiotic use, identify other infection control predictive factors for hospital antibiotic use, and evaluate the impact of enhancing different infection control practices on antibiotic use in a healthcare setting.
Morphophysiological characterization of the embryonic development of Melanotaenia praecox (Weber & de Beaufort, 1922)
Authors: Radael Marcella Costa , Cardoso Leonardo Demier , Andrade Dalcio Ricardo , Mattos Douglas , Motta Jonas Henrique , Manhães João Vitor , Vidal Manuel Vazquez 
Published: May 2013

SummaryDwarf rainbowfish (Melanotaenia praecox) are an ornamental fish with a high added value and considerable commercial interest. However, little information is known about the organism's reproductive biology, especially the early stages of embryonic development (initial ontogeny). Melanotaenia praecox embryos were examined throughout development to describe the dwarf rainbowfish initial ontogeny. Eggs were incubated at 28°C, and observations were recorded at pre-determined times. Development stages were identified and classified according to morphophysiological characteristics. The initial size of the eggs ranged between 0.99 and 1.04 mm. Oil droplets were observed in the eggs, and fixing filaments for adhesion were observed in the corium. Embryonic development was similar to that of other species in the genus Melanotaenia, in which hatching begins 119.50 h post-fertilisation or 3405.75 degree-h post-fertilisation. The main features of the newly hatched larvae were excellent swimming activity, a reduced yolk sac, mouth movement and an apparently functional digestive system.
Traditional intracytoplasmic sperm injection provides equivalent outcomes compared with human zona pellucida-bound selected sperm injection
Authors: Casciani Valentina , Minasi Maria Giulia , Fabozzi Gemma , Scarselli Filomena , Colasante Alessandro , Lobascio Anna Maria , Greco Ermanno 
Published: May 2013

SummaryThe capability of human zona pellucida (ZP) to bind selectively to normal functional sperm with normal chromatin has been reported widely in the literature. The aim of this study was to evaluate whether ZP–binding sperm selection may represent a method to retrieve superior spermatozoa for intracytoplasmic sperm injection (ICSI). Patients were divided into two groups: a ZP-ICSI and a conventional ICSI group. In the ZP-ICSI group, spermatozoa for injection were selected after ZP–sperm incubation and spermatozoa that were tightly bound to the ZP were used for ICSI (ZP-ICSI). Clinical outcomes of ZP-ICSI were compared with the outcomes of traditional scientist-selected sperm injection (conventional ICSI). Results did not show any significant difference in fertilization, pregnancy, implantation and take-home-baby rates between conventional ICSI and ZP-ICSI. However, when data relative to patients who received ZP-ICSI were analyzed, an interesting result was observed: higher sperm concentration and morphology correlated with higher ZP–sperm binding. Additionally, patients with higher ZP–sperm binding seem to have improved pregnancy and take-home-baby rates. In conclusion, this study shows that ZP-ICSI is not a superior method compared with conventional ICSI. However, clinical ICSI outcomes were apparently improved in the presence of good ZP–sperm binding. We therefore speculate that sperm competence to ICSI could be reduced when the sperm's ability to bind the ZP is impaired.
“Double whammy”: anomalous pulmonary and systemic venous drainage in a patient with scimitar syndrome
Authors: Elder Robert W. , Kogon Brian E. , Sahu Anurag 
Published: May 2013

AbstractAnomalously draining right pulmonary veins are expected with scimitar syndrome, but systemic venous abnormalities are rare. We present an unusual case of a female patient with scimitar and an interrupted inferior vena cava.