bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of treatment outcomes of childhood Hodgkin lymphoma in two US centers and a center in Recife, Brazil
Authors: Hsu Saunders C. , Metzger Monika L. , Hudson Melissa M. , Pedrosa Francisco , Lins Mecneide , Pedrosa Marcia , Barros Cynthia , Maciel Kaline , Pui Ching‐Hon , Ribeiro Raul C. , Howard Scott C. 
Published: April 2006

AbstractBackgroundPediatric Hodgkin lymphoma (HL) has a cure rate of more than 80% in high‐income countries (HIC). However, more than 80% of the world's children live in low‐income countries (LIC), where the cure rate is often much lower.ProcedureWe compared the outcome of HL of 371 patients treated at two pediatric oncology centers in the US to that of 62 patients treated at one center in Recife, Brazil (IMIP) to determine whether the same treatment strategy should be used in both high‐income and LIC. The logrank test was used to compare event‐free and overall survival.ResultsThe percentages of patients with unfavorable disease at each center were similar (P = 0.72). Patients with favorable disease at IMIP had estimated 5‐year survival rates comparable to those of the US centers (100% and 99%, respectively). Among patients with unfavorable disease, those treated at IMIP had a 5‐year event‐free survival (EFS) rate of 60%, compared to 78% at the US centers; (P = 0.08). The 5‐year survival estimate after relapse was 25% at IMIP versus 61% at the US centers (P = 0.08). The 5‐year overall survival for patients with unfavorable disease was 72% at IMIP versus 90% at the US centers (P = 0.01).ConclusionsIntensive frontline therapy should be considered for patients with unfavorable HL in LIC where the relapse rate is high and the salvage rate is low, provided that supportive care is adequate. Pediatr Blood Cancer 2007;49:139–144. © 2006 Wiley‐Liss, Inc.
Synthesis of poly(2‐hydroxyethyl methacrylate) in protic media through atom transfer radical polymerization using activators generated by electron transfer
Authors: Oh Jung Kwon , Matyjaszewski Krzysztof 
Published: April 2006

AbstractAtom transfer radical polymerization (ATRP) using activators generated by electron transfer (AGET) was investigated for the controlled polymerization of 2‐hydroxyethyl methacrylate (HEMA) in a protic solvent, a 3/2 (v/v) mixture of methyl ethyl ketone and methanol. The AGET process enabled ATRP to be started with an air‐stable Cu(II) complex that was reduced in situ by tin(II) 2‐ethylhexanoate. The reaction temperature, Cu catalysts with different ligands, and variation of the initial concentration ratio of HEMA to the initiator were examined for the synthesis of well‐controlled poly(2‐hydroxyethyl methacrylate) and a poly(methyl methacrylate)‐b‐poly(2‐hydroxyethyl methacrylate) block copolymer. The level of control in AGET ATRP was similar to that in normal ATRP in protic solvents, and this resulted in a linear increase in the molecular weight with the conversion and a narrow molecular weight distribution (weight‐average molecular weight/number‐average molecular weight < 1.3). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3787–3796, 2006
High infant and child mortality rates in Orissa: an assessment of major reasons
Authors: Pradhan Jalandhar , Arokiasamy P. 
Published: April 2006

AbstractInfant and child mortality rates in Orissa are the highest among the Indian states. This is surprising, given other demographic indicators, such as the relatively rapid fertility decline and the quite high levels of antenatal care coverage in this state compared with other comparatively poor states. In this article, the macro‐ and micro‐level determinants of high infant and child mortality are assessed using multivariate logistic regression analyses. The results demonstrate that the major contributors to the high infant and child mortality rates are the extremely low levels of health sector investments and the associated quality of care. Copyright © 2006 John Wiley & Sons, Ltd.
An introductory note to CHMP guidelines: choice of the non‐inferiority margin and data monitoring committees
Authors: Brown David , Volkers Peter , Day Simon 
Published: April 2006

AbstractThe Committee on Medical Products for Human Use (CHMP) has recently issued two new guidance documents that are of particular note to statisticians. The purpose of this short note is to give a little background to the origins of these documents and a flavour of some of their most important features. The two guidelines are reproduced as the next two papers in the journal (Stat. Med. 2006; 25:1628–1645). Copyright © 2006 John Wiley & Sons, Ltd.
The dynamics of the near field of strong jets in crossflows
Authors: Coelho Sergio L. V. , Hunt J. C. R. 
Published: April 2006

An inviscid three-dimensional vortex-sheet model for the near field of a strong jet issuing from a pipe into a crossflow is derived. The solution for this model shows that the essential mechanisms governing this idealized flow are the distortion of the main transverse vorticity by the generation of additional axial and transverse vorticity within the pipe owing to the pressure gradients induced by the external flow, and the convection of both components of vorticity from the upwind side of the jet to its downwind side.The deformation of the cross-section of the jet which is predicted by this model is compared with the deformation predicted by the commonly used time-dependent two-dimensional vortex-sheet model. Differences arise because the latter model does not take into account the effects of the transport of the transverse component of vorticity. The complete three-dimensional vortex-sheet model leads to a symmetrical deformation of the jet cross-section and no overall deflection of the jet in the direction of the stream.To account for viscous effects, the initial region of a strong jet issuing into a uniform crossflow is modelled as an entraining three-dimensional vortex sheet, which acts like a sheet of vortices and sinks, redistributing the vorticity in the bounding shear layer and inducing non-symmetrical deformations of the cross-section of the jet. This leads to a deflection of the jet in the direction of the stream, and the loci of the centroids of the cross-sections of the jet describe a quadratic curve.Deformations predicted by each of the three models are compared with measurements obtained from photographs of the cross-sections of a jet of air emerging into a uniform crossflow in a wind tunnel. Mean velocity measurements around the jet made with a hot-wire anemometer agree with the theory; they clearly invalidate models of jets based on ‘pressure drag’.
Numerical simulations of freely evolving turbulence in stably stratified fluids
Authors: Métais Olivier , Herring Jackson R. 
Published: April 2006

Results of direct numerical simulations of stably stratified, freely evolving, homogeneous turbulence are presented. An examination of initial data designed to give insight into laboratory flows suggests that the numerical simulations have a satisfactory degree of realism, insofar as statistical parameters such as total energy and length scales are concerned. The motion is decomposed into a stratified turbulence (vortical) component and a wave component. For initial-value problems similar to laboratory studies of stratified flows, the vortical component decays at a rate virtually identical to that of the non-buoyant case up to t = 6N−1 (N is the Brunt-Väisälä frequency). The decay rate decreases after this time, suggesting a kind of turbulence ‘collapse’. The temperature structure that emerges clearly shows the development of the collapse stage of the flow, which is also diagnosed by the behaviour of parameters such as the Thorpe scale.We next examine the very small-Froude-number regime in order to understand possible universal aspects of the flow. An examination of various initial conditions with different proportions of stratified and wave components indicates a lack of universality. For initial data containing only vortical motion (motions derived from the vertical vorticity field), the vortical field tends to dominate, in subsequent evolution, at strong stratification. However, contrary to two-dimensional turbulence, the flow is more strongly dissipative than two-dimensional flows due to the frictional effect associated with layering. Other quantities examined are frequency spectra, and the probability distribution for vertical shear. The frequency spectra exhibit some features in common with spectra extracted from oceanographic data.
On the flow between a porous rotating disk and a plane
Authors: Goldshtik M. A. , Javorsky N. I. 
Published: April 2006

Axisymmetric flow of viscous incompressible fluid between a rotating porous disk and an impermeable fixed plane is investigated. It is shown that with injection and suction through a porous disk rotating with sufficiently large angular velocity there are many isolated steady self-similar solutions. In the case of suction through a fixed porous disk at a certain Reynolds number there exists bifurcation of the stable rotational regime of flow, implying a spontaneous break of the flow symmetry and an arbitrary rise of the fluid rotation within the framework of self-similarity. This unusual effect is discussed in detail, and the results of a relevant experiment are presented. Another unusual result is the existence of multicellular regimes consistent with suction, when the lift force acting on a rapidly rotating porous disk is anomalously large; in this case some of these regimes are stable relative to self-similar perturbations.With sufficiently strong suction and rotation the stationary solution with large lift becomes unstable and the regime of self-oscillations arises. Diagrams of the possible stationary flow regimes have been constructed, and the stable ones have been identified. At the limit of vanishing viscosity we find, in the case of the suction, non-classical boundary layers on the solid surfaces characterized by a finite jump of the normal component of the velocity and unlimited tangential components. In this limit, in the interior flow region the singular non-viscous solution with an infinite velocity of rotation arises, while all limited non-singular admissible non-viscous solutions are not stable.
Wave patterns in plane Poiseuille flow created by concentrated disturbances
Authors: Li Fei , Widnall Sheila E. 
Published: April 2006

A model is constructed for perturbations created in the surrounding laminar flow by a turbulent spot in plane Poiseuille flow. The turbulent spot is represented as a distribution of increased Reynolds stress, which travels steadily through the surrounding laminar flow. The Navier-Stokes equations are linearized and are solved by using Fourier transforms in the plane parallel to the channel walls and a finite-difference method in the direction perpendicular to the walls. The travelling Reynolds stress distribution acts as a forcing term in the equations.Numerical results show that a packet of oblique waves are generated around the disturbance when the force is antisymmetric with respect to the channel centreline, whereas no identifiable wave crests are found when the forcing is symmetric. Furthermore, wavelengths of the typical waves composing the packet are insensitive to the size of the region of Reynolds stress. The dependencies of the flow field on Reynolds number and spot speed are investigated. In the case of symmetric forcing, the flow is forced around the disturbance, causing distortions to the basic velocity profiles. These results are in qualitative agreement with experimental observations.
Hydrodynamic theory of glancing impact
Authors: Frankel I. , Weihs D. 
Published: April 2006

Penetration of high-speed targets, such as missiles or satellites, involves a glancing impact resulting from the velocities of the target and the projectile not necessarily being parallel to one another. Glancing is different from oblique impact in that here the target is in lateral motion relative to the projectile (at speeds that may be comparable).The effect of the transverse motion of the target on the penetration performance is analysed by means of a hydrodynamic model. As is usually done, both the projectile and target materials are taken to behave as ideal fluids, owing to the large stresses obtained upon impact. A complete description of the flow field is obtained for the planar case, making use of a transformation to the hodograph plane. Owing to the lack of symmetry, the solution is obtained indirectly from the known solution for asymmetrically impinging jets, obtaining a determinate solution by a limit process where the jet representing the target fluid becomes infinitely wide.The variations of the rate of penetration and the streamline pattern with the respective ratios of target to projectile speeds and densities are studied. It is found that the relative lateral motion of the target causes a decrease in the rate of penetration (in comparison to normal impact). The analysis is utilized to obtain an estimate for the total depth of penetration (relative to the projectile width). Comparison with experimental data of yawed impact available in the open literature shows good agreement with the theoretical predictions when the latter are modified to account for the deceleration of a finite-length projectile.
On the instabilities of supersonic mixing layers: a high-Mach-number asymptotic theory
Authors: Balsa Thomas F. , Goldstein M. E. 
Published: April 2006

The stability of a family of tanh mixing layers is studied at large Mach numbers using perturbation methods. It is found that the eigenfunction develops a multilayered structure, and the eigenvalue is obtained by solving a simplified version of the Rayleigh equation (with homogeneous boundary conditions) in one of these layers which lies in either of the external streams. Our analysis leads to a simple hypersonic similarity law which explains how spatial and temporal phase speeds and growth rates scale with Mach number and temperature ratio. Comparisons are made with numerical results, and it is found that this similarity law provides a good qualitative guide for the behaviour of the instability at high Mach numbers.In addition to this asymptotic theory, some fully numerical results are also presented (with no limitation on the Mach number) in order to explain the origin of the hypersonic modes (through mode splitting) and to discuss the role of oblique modes over a very wide range of Mach number and temperature ratio.
The blockage of gravity and capillary waves by longer waves and currents
Authors: Shyu Jinn-Hwa , Phillips O. M. 
Published: April 2006

Surface waves superimposed upon a larger-scale flow are blocked at the points where the group velocities balance the convection by the larger-scale flow. Two types of blockage, capillary and gravity, are investigated by using a new multiple-scale technique, in which the short waves are treated linearly and the underlying larger-scale flows are assumed steady but can have a considerably curved surface and uniform vorticity. The technique first provides a uniformly valid second-order ordinary differential equation, from which a consistent uniform asymptotic solution can readily be obtained by using a treatment suggested by the result of Smith (1975) who described the phenomenon of gravity blockage in an unsteady current with finite depth.The corresponding WKBJ solution is also derived as a consistent asymptotic expansion of the uniform solution, which is valid at points away from the blockage point. This solution is obviously represented by a linear combination of the incident and reflected waves, and their amplitudes take explicit forms so that it can be shown that even with a significantly varied effective gravity g’ and constant vorticity, wave action will remain conserved for each wave. Furthermore, from the relative amplitudes of the incident and reflected waves, we clearly demonstrate that the action fluxes carried by the two waves towards and away from the blockage point are equal within the present approximation.The blockage of gravity–capillary waves can occur at the forward slopes of a finite-amplitude dominant wave as suggested by Phillips (1981). The results show that the blocked waves will be reflected as extremely short capillaries and then dissipated rapidly by viscosity. Therefore, for a fixed dominant wave, all wavelets shorter than a limiting wavelength will be suppressed by this process. The minimum wavelengths coexisting with the long waves of various wavelengths and slopes are estimated.
Buoyancy-driven fluid fracture: similarity solutions for the horizontal and vertical propagation of fluid-filled cracks
Authors: Lister John R. 
Published: April 2006

Buoyancy-driven flows resulting from the introduction of fluid of one density into a crack embedded in an elastic solid of different density are analysed. Scaling arguments are used to determine the regimes in which different combinations of the buoyancy force, elastic stress, viscous pressure drop and material toughness provide the dominant pressure balance in the flow. The nonlinear equations governing the shape and rate of spread of the propagating crack are formulated for the cases of vertical propagation of buoyant fluid released into a solid of greater density and of lateral propagation of fluid released at an interface between an upper layer of lesser density and a lower layer of greater density. Similarity solutions of these equations are derived under the assumption that the volume of fluid is given by Qtα, where Q and α are constants. Both laminar and turbulent flows are considered.Fluid fracture is an important mechanism for the transport of molten rock from the region of production in the Earth's mantle to surface eruptions or near-surface emplacement. The theoretical solutions provide simple models which describe the relation between the elastic and fluid-mechanical phenomena involved in the vertical transport of melt through the Earth's lithosphere and in the lateral intrusion of melt at a neutral-buoyancy level close to the Earth's surface.
Dynamical behaviour of natural convection in a single-phase loop
Authors: Ehrhard Peter , Müller Ulrich 
Published: April 2006

A one-dimensional model is derived for natural convection in a closed loop. The physical model can be reduced to a set of nonlinear ordinary differential equations of the Lorenz type. The model is based on a realistic heat transfer law and also accounts for a non-symmetric arrangement of heat sources and sinks. A nonlinear analysis of these equations is performed as well as experiments to validate the model predictions.Both the experimental and the analytical data show that natural convection in a loop is characterized by strong nonlinear effects. Distinct subcritical regions are observed in addition to a variety of stable steady flow regimes. Thus, in certain ranges of the forcing parameter the flow stability depends significantly on the presence of finite perturbation amplitudes. An absolutely unstable range also exists which is characterized by a chaotic time behaviour of the flow quantities. It is also shown that the steady solutions are subject to an imperfect forward bifurcation if heating of the loop is performed non-symmetrically. In such a case one flow direction is preferred at the onset of convection and, moreover, the corresponding steady solution is more stable than a second, isolated, steady solution. The second solution has the opposite flow direction and is stable only in a relatively small, isolated interval. The preferred steady solution becomes unstable against time-periodic perturbations at a higher value of the forcing parameter. A backward- or a forward-directed bifurcation of the periodic solutions is found depending on the non-symmetry parameter of the system.
Vortex street impinging upon an elliptical leading edge
Authors: Gursul Ismet , Rockwell Donald 
Published: April 2006

The interaction of a Kármán vortex street with an elliptical edge is investigated experimentally. Basic types of interaction, as a function of scale and transverse displacement of the incident vortex street, are revealed using flow visualization. Unsteady pressure fields induced by these interactions are measured by a phase-averaging technique and correlated with the visualized flow patterns for basic classes of interactions.For a generic vortex–edge interaction, measurements of the phase-averaged velocity field allow construction of streamlines and vorticity contours showing the details of the interaction, including distortion of the vortical structures near the edge. The pressure field is calculated from the measured velocity field and interpreted in relation to the vortical structures.Simulation of flow visualization using the measured velocity field demonstrates possible misinterpretations related to the underlying vorticity field.
The influence of wave breaking on the surface pressure distribution in wind—wave interactions
Authors: Banner Michael L. 
Published: April 2006

In reviewing the current status of our understanding of the mechanisms underlying wind-wave generation, it is apparent that existing theories and models are not applicable to situations where the sea surface is disturbed by breaking waves, and that the available experimental data on this question are sparse. In this context, this paper presents the results of a detailed study of the effects of wave breaking on the aerodynamic surface pressure distribution and consequent wave-coherent momentum flux, as well as its influence on the total wind stress.Two complementary experimental configurations were used to focus on the details and consequences of the pressure distribution over breaking waves under wind forcing. The first utilized a stationary breaking wave configuration and confirmed the presence of significant phase shifting, due to air flow separation effects, between the surface pressure and surface elevation (and slope) distributions over a range of wind speeds. The second configuration examined the pressure distribution, recorded at a fixed height above the mean water surface just above the crest level, over short mechanically triggered waves which were induced to break almost continuously under wind forcing. This allowed a very detailed comparison of the form drag for actively breaking waves and for waves of comparable steepness just prior to breaking (‘incipiently’ breaking waves). For these propagating steep-wave experiments, the pressure phase shifts and distributions closely paralleled the stationary configuration findings. Moreover, a large increase (typically 100%) in the total windstress was observed for the breaking waves, with the increase corresponding closely to the comparably enhanced form drag associated with the actively breaking waves.In addition to further elucidating some fundamental features of wind-wave interactions for very steep wind waves, this paper provides a useful data set for future model calculations of wind flow over breaking waves. The results also provide the basis for a parameterization of the wind input source function applicable for a wave field undergoing active breaking, an important result for numerical modelling of short wind waves.