bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface quality and biocompatibility of porous hydroxyapatite scaffolds for bone tissue engineering
Authors: Wu Bin , Braun Anne , Ediger Simon , Huang Wei , Lilischkis Rainer , Schäfer Karl‐Herbert , Wu Quan , Zhang Xianglin , Saumer Monika 
Published: February 2013

AbstractSurface quality and biocompatibility were critical properties of bone scaffolds. Fabrication and biological properties of porous hydroxyapatite (HA) scaffolds made by extrusion deposition method (EDM) and microwave sintering were investigated in this paper. The scaffolds with side length of 3.61 mm, height of 0.51 mm, pore size of 139 µm, Ra of 1.67 µm, and Rmax of 10.5 µm were used as substrates for osteosarcoma cells (SAOS 2) culturing to investigate the scaffolds' biological properties. Surface metrology and morphology before and after cell culture were measured to approach the interaction of cell culture with the scaffolds. The results showed that the HA scaffolds made by EDM had good biocompatibility and the surface metrology of scaffolds does not have an obvious change under cell culture even for 21 days. SAOS‐2 could attach to and grew well on scaffolds even after culturing for 21 days. And Ra and Rmax of scaffolds surfaces were 1.67 ± 0.59 µm and 10.5 ± 3.9 µm before cell culture and 1.64 ± 0.62 µm and 10.6 ± 4.5 µm after cell culture. EDTA have significant influences upon the HA grains, and the cells themselves also seem to lead to subtle scaffold degradation.
A Novel On‐Package Sticker Sensor Based on Methyl Red for Real‐Time Monitoring of Broiler Chicken Cut Freshness
Authors: Kuswandi Bambang , Jayus  , Oktaviana Revi , Abdullah Aminah , Heng Lee Yook 
Published: February 2013

ABSTRACTA novel sticker sensor has been fabricated based on methyl red, and tests have been conducted to detect the freshness of broiler chicken cuts. Methyl red was immobilized onto a bacterial cellulose membrane via absorption method. The methyl red/cellulose membrane as a freshness sensor worked based on pH increase as the basic spoilage volatile amines produced gradually in the package headspace, and subsequently, the colour of the sensor will change from red to yellow for spoilage indication, which is easily visible to the naked eye. The results show that the sticker sensor could be used to determine the degree of chicken cut freshness, as the relationship between the colour change of methyl red as a sensor response and the chicken cut freshness follows a similar trend. Therefore, the spoilage of the chicken cut could be detected visually. A sticker sensor indicates the chicken cut freshness by its colour change in real time. Thus, the sticker sensor can be used as an effective tool for monitoring the microbial quality of packaged fresh poultry meat. Finally, the methyl red/cellulose membrane was successfully used as a sticker sensor for the real‐time monitoring of chicken cut freshness in ambient and chiller conditions. Copyright © 2013 John Wiley & Sons, Ltd.
Connectivity of inhomogeneous random graphs
Authors: Devroye Luc , Fraiman Nicolas 
Published: February 2013

AbstractWe find conditions for the connectivity of inhomogeneous random graphs with intermediate density. Our results generalize the classical result for G(n, p), when . We draw n independent points Xi from a general distribution on a separable metric space, and let their indices form the vertex set of a graph. An edge (i, j) is added with probability , where is a fixed kernel. We show that, under reasonably weak assumptions, the connectivity threshold of the model can be determined. © 2013 Wiley Periodicals, Inc. Random Struct. Alg., 45, 408‐420, 2014
A simulation model of the Devils Hole pupfish population using monthly length‐frequency distributions
Authors: Dzul Maria Christina , Dinsmore Stephen James , Quist Michael Carl , Gaines Daniel Bailey , Wilson Kevin Patrick , Bower Michael Roy , Dixon Philip Michael 
Published: February 2013

AbstractThe Devils Hole pupfish, Cyprinodon diabolis, is a federally‐endangered fish that is endemic to Devils Hole, a discontiguous part of Death Valley National Park in Nye County, Nevada. Due to its status, Devils Hole pupfish monitoring must be non‐obtrusive and thereby exclude techniques that require handling fish. Due to a recent decline in pupfish abundance, Devils Hole pupfish managers have expressed a need for a model that describes population dynamics. This population model would be used to identify vulnerable life history stage(s) and inform management actions. We constructed a set of individual‐based simulation models designed to explore effects of population processes and evaluate assumptions. We developed a baseline model, whose output best resembled both observed length‐frequency data and predicted intra‐annual abundance patterns. We then ran simulations with 5 % increases in egg‐larval, juvenile, and adult survival rates to better understand Devils Hole pupfish life history, thereby helping identify vulnerable life history stages that should become the target of management actions. Simulation models with temporally constant adult, juvenile, and egg‐larval survival rates were able to reproduce observed length‐frequency distributions and predicted intra‐annual population patterns. In particular, models with monthly adult and juvenile survival rates of 80 % and an egg‐larval survival rate of 4.7 % replicated patterns in observed data. Population growth was most affected by 5 % increases in egg‐larval survival, whereas adult and juvenile survival rates had similar but lesser effects on population growth. Outputs from the model were used to assess factors suspected of influencing Devils Hole pupfish population decline.
The effect of tranexamic acid in blood loss and transfusion volume in adolescent idiopathic scoliosis surgery: A single-surgeon experience
Authors: Lykissas Marios G. , Crawford Alvin H. , Chan Gilbert , Aronson Lori A. , Al-Sayyad Mohammed J. 
Published: February 2013

Purpose Intraoperative blood loss in scoliosis surgery often requires transfusions. Autogenous blood decreases but does not eliminate risks typically associated with allogenic blood transfusion. Costs associated with transfusions are significant. Tranexamic acid (TXA) has been shown to decrease blood loss in cardiac and joint surgery. Few studies have examined its use in pediatric spine surgery, and the results are inconsistent. The aim of this study was to determine whether TXA decreases intraoperative blood loss and transfusion requirements in adolescent idiopathic scoliosis patients undergoing posterior spinal fusion by a single surgeon. Methods The medical records and operative reports of surgically treated patients with adolescent idiopathic scoliosis between 2000 and 2009 were retrospectively reviewed. The inclusion criteria were: (1) patients who underwent instrumented posterior spinal fusion, (2) had complete medical records, and (3) were treated by the same surgeon. Forty-nine patients who met the inclusion criteria were divided into two groups: Group A (25 patients) received TXA, while Group B (24 patients) did not receive TXA. Results After controlling for age at the time of surgery, gender, and number of vertebral levels fused, the mean intraoperative blood loss was significantly lower in Group A (537 ml) than in Group B (1,245 ml) ( p = 0.027). The mean volume of blood transfused intraoperatively was 426 and 740 ml for Group A and Group B, respectively. The difference was not statistically significant after controlling for age, gender, and number of levels fused ( p = 0.078). Conclusion TXA significantly decreased intraoperative blood loss in posterior spinal fusions performed for adolescent idiopathic scoliosis.
Nonlinear vorticity-banding instability in granular plane Couette flow: higher-order Landau coefficients, bistability and the bifurcation scenario
Authors: Shukla Priyanka , Alam Meheboob 
Published: February 2013

AbstractThe rapid granular plane Couette flow is known to be unstable to pure spanwise perturbations (i.e. perturbations having variations only along the mean vorticity direction) below some critical density (volume fraction of particles), resulting in the banding of particles along the mean vorticity direction: this is dubbed ‘vorticity banding’ instability. The nonlinear state of this instability is analysed using quintic-order Landau equation that has been derived from the pertinent hydrodynamic equations of rapid granular fluid. We have found analytical solutions for related modal/harmonic equations of finite-size perturbations up to quintic order in perturbation amplitude, leading to an exact calculation of both first and second Landau coefficients. This helped to identify the bistable nature of nonlinear vorticity-banding instability for a range of densities spanning from moderately dense to dense flows. For perturbations with small spanwise wavenumbers, the bifurcation scenario for vorticity banding unfolds, with increasing density from the dilute limit, as supercritical pitchfork $\rightarrow $ subcritical pitchfork $\rightarrow $ subcritical Hopf bifurcations. The transition from supercritical to subcritical pitchfork bifurcations is found to occur via the appearance of a degenerate/bicritical point (at which both the linear growth rate and the first Landau coefficient are simultaneously zero) that divides the critical line into two parts: one representing the first-order and the other the second-order phase transitions. Both subcritical oscillatory and stationary solutions have also been uncovered for dilute and dense flows, respectively, when the spanwise wavenumber is large. In all cases, the nonlinear solutions correspond to inhomogeneous states of shear stress and pressure along the vorticity direction, and hence are analogues of vorticity banding in other complex fluids. The quartic-order mean-flow resonance is evidenced in the parameter space for which the second Landau coefficient undergoes a jump discontinuity of infinite order. The importance of retaining higher-order terms to calculate the second Landau coefficient and their possible effects on the nature of bifurcations are elucidated.
Libration-induced mean flow in a spherical shell
Authors: Sauret Alban , Le Dizès Stéphane 
Published: February 2013

AbstractWe investigate the flow in a spherical shell subject to a time harmonic oscillation of its rotation rate, also called longitudinal libration, when the oscillation frequency is larger than twice the mean rotation rate. In this frequency regime, no inertial waves are directly excited by harmonic forcing. We show, however, that, through nonlinear interactions in the Ekman layers, it can generate a strong mean zonal flow in the interior. An analytical theory is developed using a perturbative approach in the limit of small libration amplitude $\varepsilon $ and small Ekman number $E$. The mean flow is found to be at leading order an azimuthal flow that scales as the square of the libration amplitude and depends only on the cylindrical radius coordinate. The mean flow also exhibits a discontinuity across the cylinder tangent to the inner sphere. We show that this discontinuity can be smoothed through multi-scale Stewartson layers. The mean flow is also found to possess a weak axial flow that scales as $O({\varepsilon }^{2} {E}^{5/ 42} )$ in the Stewartson layers. The analytical solution is compared to axisymmetric numerical simulations, and a good agreement is demonstrated.
Lattice ellipsoidal statistical BGK model for thermal non-equilibrium flows
Authors: Meng Jianping , Zhang Yonghao , Hadjiconstantinou Nicolas G. , Radtke Gregg A. , Shan Xiaowen 
Published: February 2013

AbstractA thermal lattice Boltzmann model is constructed on the basis of the ellipsoidal statistical Bhatnagar–Gross–Krook (ES-BGK) collision operator via the Hermite moment representation. The resulting lattice ES-BGK model uses a single distribution function and features an adjustable Prandtl number. Numerical simulations show that using a moderate discrete velocity set, this model can accurately recover steady and transient solutions of the ES-BGK equation in the slip-flow and early transition regimes in the small-Mach-number limit that is typical of microscale problems of practical interest. In the transition regime in particular, comparisons with numerical solutions of the ES-BGK model, direct and low-variance deviational Monte Carlo simulations show good accuracy for values of the Knudsen number up to approximately $0. 5$. On the other hand, highly non-equilibrium phenomena characterized by high Mach numbers, such as viscous heating and force-driven Poiseuille flow for large values of the driving force, are more difficult to capture quantitatively in the transition regime using discretizations chosen with computational efficiency in mind such as the one used here, although improved accuracy is observed as the number of discrete velocities is increased.
Stability of a Gaussian pancake vortex in a stratified fluid
Authors: Negretti M. Eletta , Billant Paul 
Published: February 2013

AbstractVortices in stably stratified fluids generally have a pancake shape with a small vertical thickness compared with their horizontal size. In order to understand what mechanism determines their minimum thickness, the linear stability of an axisymmetric pancake vortex is investigated as a function of its aspect ratio $\alpha $, the horizontal Froude number ${F}_{h} $, the Reynolds number $\mathit{Re}$ and the Schmidt number $\mathit{Sc}$. The vertical vorticity profile of the base state is chosen to be Gaussian in both radial and vertical directions. The vortex is unstable when the aspect ratio is below a critical value, which scales with the Froude number: ${\alpha }_{c} \sim 1. 1{F}_{h} $ for sufficiently large Reynolds numbers. The most unstable perturbation has an azimuthal wavenumber either $m= 0$, $\vert m\vert = 1$ or $\vert m\vert = 2$ depending on the control parameters. We show that the threshold corresponds to the appearance of gravitationally unstable regions in the vortex core due to the thermal wind balance. The Richardson criterion for shear instability based on the vertical shear is never satisfied alone. The dominance of the gravitational instability over the shear instability is shown to hold for a general class of pancake vortices with angular velocity of the form $\tilde {\Omega } (r, z)= \Omega (r)f(z)$ provided that $r\partial \Omega / \partial r\lt 3\Omega $ everywhere. Finally, the growth rate and azimuthal wavenumber selection of the gravitational instability are accounted well by considering an unstably stratified viscous and diffusive layer in solid body rotation with a parabolic density gradient.
Dispersive shock waves in viscously deformable media
Authors: Lowman Nicholas K. , Hoefer M. A. 
Published: February 2013

AbstractThe viscously dominated, low-Reynolds-number dynamics of multi-phase, compacting media can lead to nonlinear, dissipationless/dispersive behaviour when viewed appropriately. In these systems, nonlinear self-steepening competes with wave dispersion, giving rise to dispersive shock waves (DSWs). Example systems considered here include magma migration through the mantle as well as the buoyant ascent of a low-density fluid through a viscously deformable conduit. These flows are modelled by a third-order, degenerate, dispersive, nonlinear wave equation for the porosity (magma volume fraction) or cross-sectional area, respectively. Whitham averaging theory for step initial conditions is used to compute analytical, closed-form predictions for the DSW speeds and the leading edge amplitude in terms of the constitutive parameters and initial jump height. Novel physical behaviours are identified including backflow and DSW implosion for initial jumps sufficient to cause gradient catastrophe in the Whitham modulation equations. Theoretical predictions are shown to be in excellent agreement with long-time numerical simulations for the case of small- to moderate-amplitude DSWs. Verifiable criteria identifying the breakdown of this modulation theory in the large jump regime, applicable to a wide class of DSW problems, are presented.
Influence of membrane viscosity on capsule dynamics in shear flow
Authors: Yazdani Alireza , Bagchi Prosenjit 
Published: February 2013

AbstractMost previous numerical studies on capsule dynamics in shear flow have ignored the role of membrane viscosity. Here we present a numerical method for large deformation of capsules using a Kelvin–Voigt viscoelastic model for the membrane. After introducing the model and the related numerical implementation, we present a comprehensive analysis of the influence of the membrane viscosity on buckling, deformation and dynamics. We observe that the membrane viscosity leads to buckling in the range of shear rate in which no buckling is observed for capsules with purely elastic membrane. For moderate to large shear rates, the wrinkles on the capsule surface appear in the same range of the membrane viscosity that was reported earlier for artificial capsules and red blood cells based on experimental measurements. In order to obtain stable shapes, it is necessary to introduce the bending stiffness. It is observed that the range of the bending stiffness required is also in the same range as that reported for the red blood cells, but considerably higher than that estimated for artificial capsules. Using the stable shapes obtained in the presence of bending stiffness, we analyse the influence of membrane viscosity on deformation, inclination and tank-treading frequency of initially spherical capsules. Membrane viscosity is observed to reduce the capsule deformation, and introduce a damped oscillation in time-dependent deformation and inclination. The time-averaged inclination angle shows a non-monotonic trend with an initial decrease reaching a minimum and a subsequent increase with increasing membrane viscosity. A similar non-monotonic trend is also observed in the tank-treading frequency. We then consider the influence of the membrane viscosity on the unsteady dynamics of an initially oblate capsule. The dynamics is observed to change from a swinging motion to a tumbling motion with increasing membrane viscosity. Further, a transient dynamics is also observed in which a capsule starts with one type of dynamics, but settles with a different dynamics over a long time.
The internal gravity wave field emitted by a stably stratified turbulent wake
Authors: Abdilghanie Ammar M. , Diamessis Peter J. 
Published: February 2013

AbstractThe internal gravity wave (IGW) field emitted by a stably stratified, initially turbulent, wake of a towed sphere in a linearly stratified fluid is studied using fully nonlinear numerical simulations. A wide range of Reynolds numbers,$\mathit{Re}= UD/ \nu \in [5\times 1{0}^{3} , 1{0}^{5} ] $and internal Froude numbers,$\mathit{Fr}= 2U/ (ND)\in [4, 16, 64] $($U$,$D$are characteristic body velocity and length scales, and$N$is the buoyancy frequency) is examined. At the higher$\mathit{Re}$examined, secondary Kelvin–Helmholtz instabilities and the resulting turbulent events, directly linked to a prolonged non-equilibrium (NEQ) regime in wake evolution, are responsible for IGW emission that persists up to$Nt\approx 100$. In contrast, IGW emission at the lower$\mathit{Re}$investigated does not continue beyond$Nt\approx 50$for the three$\mathit{Fr}$values considered. The horizontal wavelengths of the most energetic IGWs, obtained by continuous wavelet transforms, increase with$\mathit{Fr}$and appear to be smaller at the higher$\mathit{Re}$, especially at late times. The initial value of these wavelengths is set by the wake height at the beginning of the NEQ regime. At the lower$\mathit{Re}$, consistent with a recently proposed model, the waves propagate over a narrow range of angles that minimize viscous decay along their path. At the higher$\mathit{Re}$, wave motion is much less affected by viscosity, at least initially, and early-time wave propagation angles extend over a broader range of values which are linked to increased efficiency in momentum extraction from the turbulent wake source.
Stabilization of a swept-wing boundary layer by distributed roughness elements
Authors: Hosseini Seyed M. , Tempelmann David , Hanifi Ardeshir , Henningson Dan S. 
Published: February 2013

AbstractThe stabilization of a swept-wing boundary layer by distributed surface roughness elements is studied by performing direct numerical simulations. The configuration resembles experiments studied by Saric and coworkers at Arizona State University, who employed this control method in order to delay transition. An array of cylindrical roughness elements are placed near the leading edge to excite subcritical cross-flow modes. Subcritical refers to the modes that are not critical with respect to transition. Their amplification to nonlinear amplitudes modifies the base flow such that the most unstable cross-flow mode and secondary instabilities are damped, resulting in downstream shift of the transition location. The experiments by Saric and coworkers were performed at low levels of free stream turbulence, and the boundary layer was therefore dominated by stationary cross-flow disturbances. Here, we consider a more complex disturbance field, which comprises both steady and unsteady instabilities of similar amplitudes. It is demonstrated that the control is robust with respect to complex disturbance fields as transition is shifted from 45 to 65 % chord.
Viscous drop in compressional Stokes flow
Authors: Zabarankin Michael , Smagin Irina , Lavrenteva Olga M. , Nir Avinoam 
Published: February 2013

AbstractThe dynamics of the deformation of a drop in axisymmetric compressional viscous flow is addressed through analytical and numerical analyses for a variety of capillary numbers, $\mathit{Ca}$, and viscosity ratios, $\lambda $. For low $Ca$, the drop is approximated by an oblate spheroid, and an analytical solution is obtained in terms of spheroidal harmonics; whereas, for the case of equal viscosities ($\lambda = 1$), the velocity field within and outside a drop of a given shape admits an integral representation, and steady shapes are found in the form of Chebyshev series. For arbitrary $Ca$ and $\lambda $, exact steady shapes are evaluated numerically via an integral equation. The critical $\mathit{Ca}$, below which a steady drop shape exists, is established for various $\lambda $. Remarkably, in contrast to the extensional flow case, critical steady shapes, being flat discs with rounded rims, have similar degrees of deformation ($D\sim 0. 75$) for all $\lambda $ studied. It is also shown that for almost the entire range of $\mathit{Ca}$ and $\lambda $, the steady shapes have accurate two-parameter approximations. The validity and implications of spheroidal and two-parameter shape approximations are examined in comparison to the exact steady shapes.