bluuebunny/crossref_metadata_2025_split huggingface dataset:
The oblique parabolic equation model for linear and nonlinear wave shoaling
Authors: Toledo Yaron 
Published: January 2013

AbstractCommon simplified models for surface gravity waves result in parabolic-type equations. These equations mostly assume a negligible reflection from the bottom variations but account for both refraction and diffraction effects. A common deficiency of these equations is an inherent assumption of normally incident waves, which cause an increasing error, as the incident waves propagate from an increasing attack angle. In the nonlinear formulation of this type of equation, previous research added the assumption of small crossing angles between interacting waves, which also limits the applicability of these nonlinear models to narrow directional spectra. The current paper presents a parabolic approximation for oblique incident waves that overcomes these limitations. This is done by introducing a perturbation solution for the wave’s phase function, which in its lowest order corresponds to oblique incident waves on a bottom with no lateral changes. The resulting curved wave ray structure replaces the simplified straight one used in the derivation process of various former models. In the nonlinear model, the nonlinear interactions are calculated between the frequency modes while taking into account the different propagating directions. Numerical results of the oblique parabolic equation show great advantages compared to other formulations that use a straight wave ray structure and the small crossing angle assumption. The nonlinear model was used to investigate the nonlinear shoaling of two similar monochromatic waves approaching from different angles. This fundamental nonlinear interaction problem shows that there is an energy transfer to waves of the primary harmonic that approach at larger attack angles than the two incident waves. This is counter-intuitive. Unlike in the case of linear wave shoaling, where the waves reduce their attack angle in the refraction process, in the nonlinear shoaling process the attack angle can increase. Fundamental numerical simulations of the linear and nonlinear oblique parabolic models are shown to be in excellent agreement with the initial mild-slope equations. This confirms the benefits of applying these models to various shoaling scenarios for both linear and nonlinear waves.
Clustering and turbulence modulation in particle-laden shear flows
Authors: Gualtieri P. , Picano F. , Sardina G. , Casciola C. M. 
Published: January 2013

AbstractTurbulent fluctuations induce the common phenomenon known as clustering in the spatial arrangement of small inertial particles transported by the fluid. Particles spread non-uniformly, and form clusters where their local concentration is much higher than in nearby rarefaction regions. The underlying physics has been exhaustively analysed in the so-called one-way coupling regime, i.e. negligible back-reaction of the particles on the fluid, where the mean flow anisotropy induces preferential orientation of the clusters. Turbulent transport in suspensions with significant mass in the disperse phase, i.e. particles back-reacting in the carrier phase (the two-way coupling regime), has instead been much less investigated and is still poorly understood. The issue is discussed here by addressing direct numerical simulations of particle-laden homogeneous shear flows in the two-way coupling regime. Consistent with previous findings, we observe an overall depletion of the turbulent fluctuations for particles with response time of the order of the Kolmogorov time scale. The depletion occurs in the energy-containing range, while augmentation is observed in the small-scale range down to the dissipative scales. Increasing the mass load results in substantial broadening of the energy cospectrum, thereby extending the range of scales driven by anisotropic production mechanisms. As discussed throughout the paper, this is due to the clusters which form the spatial support of the back-reaction field and give rise to a highly anisotropic forcing, active down to the smallest scales. A certain impact on two-phase flow turbulence modelling is expected from the above conclusions, since the frequently assumed small-scale isotropy is poorly recovered when the coupling between the phases becomes significant.
Normal stresses in concentrated non-Brownian suspensions
Authors: Dbouk T. , Lobry L. , Lemaire E. 
Published: January 2013

AbstractWe present an experimental approach used to measure both normal stress differences and the particle phase contribution to the normal stresses in suspensions of non-Brownian hard spheres. The methodology consists of measuring the radial profile of the normal stress along the velocity gradient direction in a torsional flow between two parallel discs. The values of the first and the second normal stress differences, ${N}_{1} $ and ${N}_{2} $, are deduced from the measurement of the slope and of the origin ordinate. The measurements are carried out for a wide range of particle volume fractions (between 0.2 and 0.5). As expected, ${N}_{2} $ is measured to be negative but ${N}_{1} $ is found to be positive. We discuss the validity of the method and present numerous tests that have been carried out in order to validate our results. The experimental setup also allows the pore pressure to be measured. Then, subtracting the pore pressure from the total stress, ${\mbrm{\Sigma} }_{\mathbf{22} } $, the contribution of the particles to the normal stress ${ \mbrm{\Sigma} }_{\mathbf{22} }^{\mathbi{p}} $ is obtained. Most of our results compare well with the different experimental and numerical data present in the literature. In particular, our results show that the magnitude of the particle stress tensor component and their dependence on the particle volume fraction used in the suspension model balance proposed by Morris & Boulay (J. Rheol., vol. 43, 1999, p. 1213) are suitable.
Validation and modification of asymptotic analysis of slow and rapid droplet spreading by numerical simulation
Authors: Sui Yi , Spelt Peter D. M. 
Published: January 2013

AbstractUsing a slip-length-based level-set approach with adaptive mesh refinement, we have simulated axisymmetric droplet spreading for a dimensionless slip length down to$O(1{0}^{\ensuremath{-} 4} )$. The main purpose is to validate, and where necessary improve, the asymptotic analysis of Cox (J. Fluid Mech., vol. 357, 1998, pp. 249–278) for rapid droplet spreading/dewetting, in terms of the detailed interface shape in various regions close to the moving contact line and the relation between the apparent angle and the capillary number based on the instantaneous contact-line speed,$\mathit{Ca}$. Before presenting results for inertial spreading, simulation results are compared in detail with the theory of Hocking & Rivers (J. Fluid Mech., vol. 121, 1982, pp. 425–442) for slow spreading, showing that these agree very well (and in detail) for such small slip-length values, although limitations in the theoretically predicted interface shape are identified; a simple extension of the theory to viscous exterior fluids is also proposed and shown to yield similar excellent agreement. For rapid droplet spreading, it is found that, in principle, the theory of Cox can predict accurately the interface shapes in the intermediate viscous sublayer, although the inviscid sublayer can only be well presented when capillary-type waves are outside the contact-line region. However,$O(1)$parameters taken to be unity by Cox must be specified and terms be corrected to${\mathit{Ca}}^{+ 1} $in order to achieve good agreement between the theory and the simulation, both of which are undertaken here. We also find that the apparent angle from numerical simulation, obtained by extrapolating the interface shape from the macro region to the contact line, agrees reasonably well with the modified theory of Cox. A simplified version of the inertial theory is proposed in the limit of negligible viscosity of the external fluid. Building on these results, weinvestigate the flow structure near the contact line, the shear stress and pressure along the wall, and the use of the analysis for droplet impact and rapid dewetting. Finally, we compare the modified theory of Cox with a recent experiment for rapid droplet spreading, the results of which suggest a spreading-velocity-dependent dynamic contact angle in the experiments. The paper is closed with a discussion of the outlook regarding the potential of using the present results in large-scale simulations wherein the contact-line region is not resolved down to the slip length, especially for inertial spreading.
A two-dimensional vortex condensate at high Reynolds number
Authors: Gallet Basile , Young William R. 
Published: January 2013

AbstractWe investigate solutions of the two-dimensional Navier–Stokes equation in a $\lrm{\pi} \ensuremath{\times} \lrm{\pi} $ square box with stress-free boundary conditions. The flow is steadily forced by the addition of a source $\sin nx\sin ny$ to the vorticity equation; attention is restricted to even $n$ so that the forcing has zero integral. Numerical solutions with $n= 2$ and $6$ show that at high Reynolds numbers the solution is a domain-scale vortex condensate with a strong projection on the gravest mode, $\sin x\sin y$. The sign of the vortex condensate is selected by a symmetry-breaking instability. We show that the amplitude of the vortex condensate has a finite limit as $\nu \ensuremath{\rightarrow} 0$. Using a quasilinear approximation we make an analytic prediction of the amplitude of the condensate and show that the amplitude is determined by viscous selection of a particular solution from a family of solutions to the forced two-dimensional Euler equation. This theory indicates that the condensate amplitude will depend sensitively on the form of the dissipation, even in the undamped limit. This prediction is verified by considering the addition of a drag term to the Navier–Stokes equation and comparing the quasilinear theory with numerical solution.
Stability analysis of experimental flow fields behind a porous cylinder for the investigation of the large-scale wake vortices
Authors: Camarri Simone , Fallenius Bengt E. G. , Fransson Jens H. M. 
Published: January 2013

AbstractWhen the linear stability analysis is applied to the time-averaged flow past a circular cylinder after the primary instability of the wake, a nearly marginally stable global mode is predicted with a frequency in time equal to that of the saturated vortex shedding. This behaviour has recently been shown to hold up to Reynolds number$\mathit{Re}= 600$by direct numerical simulations. In the present work we verify that the global stability analysis provides reasonable estimation also when applied to experimental velocity fields measured in the wake past a porous circular cylinder at$\mathit{Re}\simeq 3. 5\ensuremath{\times} 1{0}^{3} $. Different intensities of continuous suction and blowing through the entire surface of the cylinder are considered. The global direct and adjoint stability modes, derived from the experimental data, are used to sort the random instantaneous snapshots of the velocity field in phase. The proposed method is remarkable, sorting the snapshots in phase with respect to the vortex shedding, allowing phase-averaged velocity fields to be extracted from the experimental database. The phase-averaged flow fields are analysed in order to study the effect of the transpiration on the kinematical characteristics of the large-scale wake vortices.
Oral intake of heat-killed cells ofLactococcus lactisstrain H61 promotes skin health in women
Authors: Kimoto-Nira Hiromi , Aoki Reiji , Sasaki Keisuke , Suzuki Chise , Mizumachi Koko 
Published: January 2013

AbstractWe conducted a double-blind, placebo-controlled trial to evaluate the effect of heat-killed cells ofLactococcus lactisstrain H61 on various skin properties of Japanese women. Volunteers (age 31–62 years) were randomly assigned to receive test food with or without 60 mg of heat-killed strain H61 (fifteen women in each group; H61 and control groups, respectively) daily for 8 weeks. Results were analysed for three age categories (30s, 40s and 50–60s). Compared with that at week 0, skin hydration at the inner forearm at weeks 4 and 8 decreased in all volunteers (except those in their 50–60s) because of the environmental change from autumn to winter. The oldest H61 group maintained skin hydration at the inner forearm throughout the study. Skin elasticity and melanin content in the cheek decreased and sebum content increased throughout the test period due to seasonal environmental change, regardless of age or H61 treatment. Self-evaluation scores for apparent hair follicles and dryness of the throat at week 8 were higher in the overall H61 group than in the combined placebo group. The 30s H61 group noted marked improvements in self-surveyed skin elasticity at week 8 compared with at week 0 and with the placebo group at week 8. The results of the present study indicate that oral intake of heat-killed cells ofL. lactisstrain H61 can improve some skin properties and body characteristics in women. This strain would probably be useful in increasing the quality of life in an ageing population.
In comparison with palm oil, dietary nut supplementation delays the progression of atherosclerotic lesions in female apoE-deficient mice
Authors: Surra Joaquín C. , Barranquero Cristina , Torcal María P. , Orman Israel , Segovia Jose C. , Guillén Natalia , Navarro María A. , Arnal Carmen , Osada Jesús 
Published: January 2013

Epidemiological studies have demonstrated the benefits of nut consumption on cardiovascular risk factors and CHD, attributed to their fatty acid profile, rich in unsaturated fatty acids, and also to other nutrients. The effect of nuts on atherosclerotic lesions was studied in female and male apoE-knockout mice fed a diet supplemented with 3 % (w/w) mixed nuts (mix: almonds, hazelnuts and walnuts in a proportion of 0·25:0·25:0·50, respectively), and compared with mice receiving an isoenergetic diet of similar fat content provided as palm oil. After 12 weeks, plasma lipid parameters and aortic lesions were measured. Males receiving nuts had lower plasma cholesterol than the palm oil group, and both sex groups had lower plasma non-HDL-cholesterol and lower content of reactive oxygen species in LDL than mice receiving the palm oil diet, the latter decrease being more pronounced in females than in males. Females consuming the nut diet showed a smaller aortic lesion area than those consuming palm oil, whereas no differences were observed in males. In females, hepatic paraoxonase 2 (Pon2) mRNA increased, and no change was observed in prenylcysteine oxidase 1 (Pcyox1) expression after the consumption of the nut-containing diet. In addition, aortic atherosclerotic lesions correlated directly with total plasma cholesterol and inversely with hepaticPon2expression. The results suggest that the beneficial effect of nut intake in female apoE-deficient mice may be attributed to reduced non-HDL-cholesterol levels and enhanced PON2 antioxidant activity.
INTENSIVE SLAVE RAIDING IN THE COLONIAL INTERSTICE: HAMMAN YAJI AND THE MANDARA MOUNTAINS (NORTH CAMEROON AND NORTH-EASTERN NIGERIA)
Authors: VAN BEEK WALTER E. A. 
Published: January 2013

ABSTRACTA rare document, the diary of a slave raider, offers a unique view into the sociopolitical situation at the turn of the nineteenth century in the colonial backwater of North Cameroon. The Fulbe chief in question, Hamman Yaji, not only kept a diary, but was by far the most notorious slave raider of the Mandara Mountains. This article supplements the data from his diary with oral histories and archival sources to follow the dynamics of the intense slave raiding he engaged in. This frenzy of slaving occurred in a ‘colonial interstice’ characterized by competition between three colonial powers – the British, the Germans and the French, resilient governing structures in a region poorly controlled by colonial powers, and the unclear boundaries of the Mandara Mountains. The dynamics of military technology and the economics of this ‘uncommon market’ in slaves form additional factors in this episode in the history of slavery in Africa. These factors account for the general situation of insecurity due to slave raiding in the area, to which Hamman Yaji was an exceptionally atrocious contributor. In the end a religious movement, Mahdism, stimulated the consolidation of colonial power, ending Yaji's regime, which in all its brutality provides surprising insight in the early colonial situation in this border region between Nigeria and Cameroon.
RETHINKING POLITICS IN THE COLONY: THEMÉTISOF SENEGAL AND URBAN POLITICS IN THE LATE NINETEENTH AND EARLY TWENTIETH CENTURY
Authors: JONES HILARY 
Published: January 2013

ABSTRACTSenegal was unique in French West Africa for the nature and extent of electoral institutions that operated in its colonial towns. In the 1870s, Third Republic France elaborated on earlier short-lived policies by re-establishing local assemblies and a legislative seat for Senegal in Paris. Although histories of modern politics focus on Blaise Diagne's 1914 election to the French National Assembly, a local assembly called the General Council held greater power over economic and political matters affecting the colony between 1870 and 1920. This article reconsiders the history of urban politics in colonial Senegal by examining the ways that themétis(mixed race population) used the General Council as their field of engagement with French officials, sometimes facilitating the consolidation of French rule but at other times contesting colonial practice.
‘HOOLIGANS, SPIVS AND LOAFERS’? : THE POLITICS OF VAGRANCY IN 1960s SOUTHERN RHODESIA
Authors: ALEXANDER JOCELYN 
Published: January 2013

ABSTRACTIn 1960, amidst the most violent period of protest since conquest, the Southern Rhodesian government implemented a new Vagrancy Act alongside a range of repressive legislation. The Act's origins lay in a particular analysis of the social origins of unrest. It was unprecedented in promising not to exclude and criminalise ‘vagrants’ but to rehabilitate them as productive urban citizens. By presenting the Act as reformist and progressive, the government sought legitimacy for its actions. In fact, the Vagrancy Act was deeply punitive, underlining the tensions between reform and repression in settler social engineering. African leaders and Africans targeted by the Act saw it as a means of humiliating and criminalising those denied a livelihood by the settler political economy. In rejecting the Act, they invoked different models of citizenship to those on offer from the state. The Vagrancy Act ultimately met its demise at the hands of the Rhodesian Front, whose analysis of African protest made no space for the possibilities of reformist social engineering.
Mr Upjohn's Debts: Money and friendship in early colonial Calcutta
Authors: ROBB PETER 
Published: January 2013

AbstractThe paper discusses the effective operation of money and credit among Europeans in Calcutta around 1800, arguing for the importance of informal processes and ties of friendship that facilitated, regulated, and enforced agreements, helping both to tide over individuals in times of economic stress and to underwrite the provision and transfer of capital. The argument is advanced by a detailed case-study of debts owed by one resident—Aaron Upjohn—to another, the diarist, Richard Blechynden, amid a web of acquaintance, officialdom, and law that variously ensured that the debts were honoured. It is defined as a support system among acquaintances, necessitated in part by shortage of money and abundance of risk.
Modeling and treating internalizing psychopathology in a clinical trial: a latent variable structural equation modeling approach
Authors: Kushner M. G. , Krueger R. F. , Wall M. M. , Maurer E. W. , Menk J. S. , Menary K. R. 
Published: January 2013

BackgroundClinical trials are typically designed to test the effect of a specific treatment on a single diagnostic entity. However, because common internalizing disorders are highly correlated (‘co-morbid’), we sought to establish a practical and parsimonious method to characterize and quantify changes in a broad spectrum of internalizing psychopathology targeted for treatment in a clinical trial contrasting two transdiagnostic psychosocial interventions.MethodAlcohol dependence treatment patients who had any of several common internalizing disorders were randomized to a six-session cognitive-behavioral therapy (CBT) experimental treatment condition or a progressive muscle relaxation training (PMRT) comparison treatment condition. Internalizing psychopathology was characterized at baseline and 4 months following treatment in terms of the latent structure of six distinct internalizing symptom domain surveys.ResultsExploratory structural equation modeling (ESEM) identified a two-factor solution at both baseline and the 4-month follow-up: Distress (measures of depression, trait anxiety and worry) and Fear (measures of panic anxiety, social anxiety and agoraphobia). Although confirmatory factor analysis (CFA) demonstrated measurement invariance between the time-points, structural models showed that the latent means of Fear and Distress decreased substantially from baseline to follow-up for both groups, with a small but statistically significant advantage for the CBT group in terms of Distress (but not Fear) reduction.ConclusionsThe approach demonstrated in this study provides a practical solution to modeling co-morbidity in a clinical trial and is consistent with converging evidence pointing to the dimensional structure of internalizing psychopathology.
Embarrassment when illness strikes a close relative: a World Mental Health Survey Consortium Multi-Site Study
Authors: Ahmedani B. K. , Kubiak S. P. , Kessler R. C. , de Graaf R. , Alonso J. , Bruffaerts R. , Zarkov Z. , Viana M. C. , Huang Y. Q. , Hu C. , Posada-Villa J. A. , Lepine J.-P. , Angermeyer M. C. , de Girolamo G. , Karam A. N. , Medina-Mora M. E. , Gureje O. , Ferry F. , Sagar R. , Anthony J. C. 
Published: January 2013

BackgroundIn this global study we sought to estimate the degree to which a family member might feel embarrassed when a close relative is suffering from an alcohol, drug, or mental health condition (ADMC) versus a general medical condition (GMC). To date, most studies have considered embarrassment and stigma in society and internalized by the afflicted individual but have not assessed family embarrassment in a large-scale study.MethodIn 16 sites of the World Mental Health Surveys (WMHS), standardized assessments were completed including items on family embarrassment. Site matching was used to constrain local socially shared determinants of stigma-related feelings, enabling a conditional logistic regression model that estimates the embarrassment close relatives may hold in relation to family members affected by an ADMC, a GMC, or both conditions.ResultsThere was a statistically robust association such that subgroups with an ADMC-affected relative were more likely to feel embarrassed compared to subgroups with a relative affected by a GMC (p < 0.001), even with covariate adjustments for age and sex.ConclusionsThe pattern of evidence from this research is consistent with conceptual models for interventions that target individual- and family-level stigma-related feelings of embarrassment as possible obstacles to effective early intervention and treatment for an ADMC. Macro-level interventions are under way but micro-level interventions may also be required among family members, along with care for each person with an ADMC.