bluuebunny/crossref_metadata_2025_split huggingface dataset:
A prediction model to calculate probability of Alzheimer's disease using cerebrospinal fluid biomarkers
Authors: Spies Petra E. , Claassen Jurgen A.H.R. , Peer Petronella G.M. , Blankenstein Marinus A. , Teunissen Charlotte E. , Scheltens Philip , van der Flier Wiesje M. , Olde Rikkert Marcel G.M. , Verbeek Marcel M. 
Published: November 2012

AbstractBackgroundWe aimed to develop a prediction model based on cerebrospinal fluid (CSF) biomarkers, that would yield a single estimate representing the probability that dementia in a memory clinic patient is due to Alzheimer's disease (AD).MethodsAll patients suspected of dementia in whom the CSF biomarkers had been analyzed were selected from a memory clinic database. Clinical diagnosis was AD (n = 272) or non‐AD (n = 289). The prediction model was developed with logistic regression analysis and included CSF amyloid β42, CSF phosphorylated tau181, and sex. Validation was performed on an independent data set from another memory clinic, containing 334 AD and 157 non‐AD patients.ResultsThe prediction model estimated the probability that AD is present as follows: p(AD) = 1/(1 + e – [–0.3315 + score]), where score is calculated from –1.9486 × ln(amyloid β42) + 2.7915 × ln(phosphorylated tau181) + 0.9178 × sex (male = 0, female = 1). When applied to the validation data set, the discriminative ability of the model was very good (area under the receiver operating characteristic curve: 0.85). The agreement between the probability of AD predicted by the model and the observed frequency of AD diagnoses was very good after taking into account the difference in AD prevalence between the two memory clinics.ConclusionsWe developed a prediction model that can accurately predict the probability of AD in a memory clinic population suspected of dementia based on CSF amyloid β42, CSF phosphorylated tau181, and sex.
Hierarchical Bayesian cognitive processing models to analyze clinical trial data
Authors: Shankle William R. , Hara Junko , Mangrola Tushar , Hendrix Suzanne , Alva Gus , Lee Michael D. 
Published: November 2012

AbstractIdentifying disease‐modifying treatment effects in earlier stages of Alzheimer's disease (AD)—when changes are subtle—will require improved trial design and more sensitive analytical methods. We applied hierarchical Bayesian analysis with cognitive processing (HBCP) models to the Alzheimer's Disease Assessment Scale—Cognitive subscale (ADAS‐Cog) and MCI (mild cognitive impairment) Screen word list memory task data from 14 Alzheimer's disease AD patients of the Myriad Pharmaceuticals' phase III clinical trial of Flurizan (a γ‐secretase modulator) versus placebo. The original analysis of 1649 patients found no treatment group differences. HBCP analysis and the original ADAS‐Cog analysis were performed on the small sample. HBCP analysis detected impaired memory storage during delayed recall, whereas the original ADAS‐Cog analytical method did not. The HBCP model identified a harmful treatment effect in a small sample, which has been independently confirmed from the results of other γ‐secretase inhibitor. The original analytical method applied to the ADAS‐Cog data did not detect this harmful treatment effect on either the full or the small sample. These findings suggest that HBCP models can detect treatment effects more sensitively than currently used analytical methods required by the Food and Drug Administration, and they do so using small patient samples.
The ADAS‐Cog revisited: Novel composite scales based on ADAS‐Cog to improve efficiency in MCI and early AD trials
Authors: Raghavan Nandini , Samtani Mahesh N. , Farnum Michael , Yang Eric , Novak Gerald , Grundman Michael , Narayan Vaibhav , DiBernardo Allitia ,   Alzheimer's Disease Neuroimaging Initiative
Published: November 2012

BackgroundThe Alzheimer's Disease Assessment Scale‐Cognitive (ADAS‐Cog) has been used widely as a cognitive end point in Alzheimer's Disease (AD) clinical trials. Efforts to treat AD pathology at earlier stages have also used ADAS‐Cog, but failure in these trials can be difficult to interpret because the scale has well‐known ceiling effects that limit its use in mild cognitive impairment (MCI) and early AD. A wealth of data exists in ADAS‐Cog from both historical trials and contemporary longitudinal natural history studies that can provide insights about parts of the scale that may be better suited for MCI and early AD trials.MethodsUsing Alzheimer's Disease Neuroimaging Initiative study data, we identified the most informative cognitive measures from the ADAS‐Cog and other available scales. We used cross‐sectional analyses to characterize trajectories of ADAS‐Cog and its individual subscales, as well as other cognitive, functional, or global measures across disease stages. Informative measures were identified based on standardized mean of 2‐year change from baseline and were combined into novel composite endpoints. We assessed performance of the novel endpoints based on sample size requirements for a 2‐year clinical trial. A bootstrap validation procedure was also undertaken to assess the reproducibility of the standardized mean changes of the selected measures and the corresponding composites.ResultsAll proposed novel endpoints have improved standardized mean changes and thus improved statistical power compared with the ADAS‐Cog 11. Further improvements were achieved by using cognitive–functional composites. Combining the novel composites with an enrichment strategy based on cerebral spinal fluid beta‐amyloid (Aβ1‐42) in a 2‐year trial yielded gains in power of 20% to 40% over ADAS‐Cog 11, regardless of the novel measure considered.ConclusionAn empirical, data‐driven approach with e xisting instruments was used to derive novel composite scales based on ADAS‐Cog 11 with improved performance characteristics for MCI and early AD clinical trials. Together with patient enrichment based on Aβ1‐42 pathology, these modified endpoints may allow more efficient clinical trials in these populations and can be assessed without modifying current test administration procedures in ongoing trials.
A Prospective Study on the Outcome of Degenerative Lumbar Spinal Stenosis Treated with Open Laminotomy
Authors: Martin Wong Chung-Ting , Andrew Chan Pak-Ho , Ka-Kin Cheung 
Published: November 2012

Background Laminotomy is one of the surgical treatments for spinal stenosis. Method We conducted a prospective study including 58 patients with mean follow-up of 37.5 months, successful rate was 72%. Result There were significant improvement of mean Japanese Orthopaedic Association lumbar score, Oswestry Disability Index(ODI), and visual analogue scale (VAS). Male had significantly better result in ODI and VAS. There was no significant difference regarding to older age (>65) or the presence of preexisting degenerative spondylolisthesis. One patient was found to have increased lumbar instability after operation. The overall reoperation rate was 6.9%.
Forschung in den Gesundheitsfachberufen – Potenziale für eine bedarfsgerechte Gesundheitsversorgung in Deutschland
Authors: Höppner Heidi 
Published: November 2012

Einleitung
2009-2011 erarbeitete eine Expertengruppe - eingesetzt durch den Gesundheitsforschungsrat (BMBF) ein Konzept, das Potentiale für die Gesundheitsversorgung durch Forschung in den Bereichen Logopädie, Hebammenwesen, Pflege sowie Ergo- und Logopädie aufzeigt. Der GFR sprach 2011 explizit Empfehlungen aus, künftig Forschung durch die Gesundheitsfachberufe zu fördern. Im 2012 veröffentlichten Konzept werden die unterschiedlichen Förderansätze aufgezeigt: z. B. das Nutzbarmachen der spezifischen Beiträge zu interdisziplinären Forschungsthemen, Bedingungen der wissenschaftlichen Nachwuchsförderung und vor allem die strukturellen Voraussetzungen von Forschung für eine bedarfsgerechte Versorgung durch Gesundheitsfachberufe vor dem Hintergrund veränderter Bedarfe und des sozialen Wandels.
Akkreditierung im Dienste der Qualitätssicherung von Studiengängen
Authors: Walkenhorst Ursula 
Published: November 2012

Einleitung
Akkreditierungen bilden ein wesentliches Instrument zur Qualitätssicherung an Hochschulen im Bereich von Studium und Lehre. Sie dienen der Überprüfung der Qualität der Zielsetzung sowie der Qualität der Zielerreichung von Programmen und Systemen und orientieren sich dabei an hochschul- und programmunabhängigen Kriterien. Im Zuge der Akademisierung der Gesundheitsberufe erhalten Akkreditierungsverfahren eine besondere Bedeutung, da hochschulrechtliche und berufsgesetzliche Vorgaben meist nicht kompatibel sind.
Parametric forcing approach to rough-wall turbulent channel flow
Authors: Busse A. , Sandham N. D. 
Published: November 2012

AbstractThe effects of rough surfaces on turbulent channel flow are modelled by an extra force term in the Navier–Stokes equations. This force term contains two parameters, related to the density and the height of the roughness elements, and a shape function, which regulates the influence of the force term with respect to the distance from the channel wall. This permits a more flexible specification of a rough surface than a single parameter such as the equivalent sand grain roughness. The effects of the roughness force term on turbulent channel flow have been investigated for a large number of parameter combinations and several shape functions by direct numerical simulations. It is possible to cover the full spectrum of rough flows ranging from hydraulically smooth through transitionally rough to fully rough cases. By using different parameter combinations and shape functions, it is possible to match the effects of different types of rough surfaces. Mean flow and standard turbulence statistics have been used to compare the results to recent experimental and numerical studies and a good qualitative agreement has been found. Outer scaling is preserved for the streamwise velocity for both the mean profile as well as its mean square fluctuations in all but extremely rough cases. The structure of the turbulent flow shows a trend towards more isotropic turbulent states within the roughness layer. In extremely rough cases, spanwise structures emerge near the wall and the turbulent state resembles a mixing layer. A direct comparison with the study of Ashrafian, Andersson & Manhart (Intl J. Heat Fluid Flow, vol. 25, 2004, pp. 373–383) shows a good quantitative agreement of the mean flow and Reynolds stresses everywhere except in the immediate vicinity of the rough wall. The proposed roughness force term may be of benefit as a wall model for direct and large-eddy numerical simulations in cases where the exact details of the flow over a rough wall can be neglected.
A numerical study of granular shear flows of rod-like particles using the discrete element method
Authors: Guo Y. , Wassgren C. , Ketterhagen W. , Hancock B. , James B. , Curtis J. 
Published: November 2012

AbstractThe effect of particle aspect ratio and surface geometry on granular flows is assessed by performing numerical simulations of rod-like particles in simple shear flows using the discrete element method (DEM). The effect of particle surface geometry is explored by adopting two types of particles: glued-spheres particles and true cylindrical particles. The particle aspect ratio varies from one to six. Compared to frictionless spherical particles, smaller stresses are obtained for the glued-spheres and cylindrical particle systems in dilute and moderately dense flows due to the loss of translational energy, which is partially converted to rotational energy, for the non-spherical particles. For dilute granular flows of non-spherical particles, stresses are primarily affected by the particle aspect ratio rather than the surface geometry. As the particle aspect ratio increases, the effective particle projected area in the plane perpendicular to the flow direction increases, so that the probability of the occurrence of the particle collisions increases, leading to a reduction in particle velocity fluctuation and therefore a decrease in the stresses. Hence, a simple modification is made to the kinetic theory for granular flows to describe the stress tensors for dilute flows of non-spherical particles by incorporating a normalized effective particle projected area to account for the effect of particle collision probability. For dense granular flows, the stresses depend on both the particle aspect ratio and the surface geometry. Sharp stress increases at high solid volume fractions are observed for the glued-spheres particles with large aspect ratios due to the bumpy surfaces, which impede the flow. However, smaller stresses are obtained for the true cylindrical particles with large aspect ratios at high solid volume fractions. This trend is attributed to the combined effects of the smooth particle surfaces and the particle alignments such that the major/long axes of particles are aligned in the flow direction. In addition, the apparent friction coefficient, defined as the ratio of shear to normal stresses, is found to decrease as the particle aspect ratio increases and/or the particle surface becomes smoother at high solid volume fractions.
Formation process of the vortex ring generated by an impulsively started circular disc
Authors: Yang An-long , Jia Lai-bing , Yin Xie-zhen 
Published: November 2012

AbstractWe present an experimental study on the axisymmetric vortex ring generated by a thin circular disc. The velocity and vorticity fields are measured by digital particle image velocimetry (DPIV). The finite-time Lyapunov exponent fields and the Lagrangian coherent structures (LCSs) of the vortex flow are computed in order to analyse the transport of the fluid during its formation and identify the boundary of the vortex ring. The volume, circulation and energy of the vortex ring are calculated. It is found that the formation of the vortex ring basically includes three phases: a rapid growth phase, a stable growth phase and a non-axisymmetric phase. In the rapid growth phase (dimensionless time $0\lt {T}_{n} \lt 0. 2$) during which Taylor’s inviscid estimation is valid, the circulation of the vortex ring grows and the translational velocity of the vortex ring decreases. In the stable growth phase ($0. 2\lt {T}_{n} \lt 4$), the growth rate of the circulation decreases gradually. In the non-axisymmetric phase (${T}_{n} \gt 4$), the ring loses axisymmetry due to instability. Compared with the vortex ring generated by the laminar flow from an orifice, the one generated by a circular disc always moves with the disc, and the entrained fluid decreases and the saturated circulation increases. The temporal impulse exerted by the moving disc on the fluid is estimated by DPIV measurements and is calculated using the direct momentum conservation method. The momentum of the control volume enclosing the LCS is found to occupy 64–68 % of the entire impulse exerted by the disc on the fluid.
Double diffusive effects on pressure-driven miscible displacement flows in a channel
Authors: Mishra Manoranjan , De Wit A. , Sahu Kirti Chandra 
Published: November 2012

AbstractThe pressure-driven miscible displacement of a less viscous fluid by a more viscous one in a horizontal channel is studied. This is a classically stable system if the more viscous solution is the displacing one. However, we show by numerical simulations based on the finite-volume approach that, in this system, double diffusive effects can be destabilizing. Such effects can appear if the fluid consists of a solvent containing two solutes both influencing the viscosity of the solution and diffusing at different rates. The continuity and Navier–Stokes equations coupled to two convection–diffusion equations for the evolution of the solute concentrations are solved. The viscosity is assumed to depend on the concentrations of both solutes, while density contrast is neglected. The results demonstrate the development of various instability patterns of the miscible ‘interface’ separating the fluids provided the two solutes diffuse at different rates. The intensity of the instability increases when increasing the diffusivity ratio between the faster-diffusing and the slower-diffusing solutes. This brings about fluid mixing and accelerates the displacement of the fluid originally filling the channel. The effects of varying dimensionless parameters, such as the Reynolds number and Schmidt number, on the development of the ‘interfacial’ instability pattern are also studied. The double diffusive instability appears after the moment when the invading fluid penetrates inside the channel. This is attributed to the presence of inertia in the problem.
Force and power of flapping plates in a fluid
Authors: Li Gao-Jin , Lu Xi-Yun 
Published: November 2012

AbstractThe force and power of flapping plates are studied by vortex dynamic analysis. Based on the dynamic analysis of the numerical results of viscous flow past three-dimensional flapping plates, it is found that the force and power are strongly dominated by the vortical structures close to the body. Further, the dynamics of the flapping plate is investigated in terms of viscous vortex-ring model. It is revealed that the model can reasonably reflect the essential properties of the ring-like vortical structure in the wake, and the energy of the plate transferred to the flow for the formation of each vortical structure possesses a certain relation. Moreover, simplified formulae for the thrust and efficiency are proposed and verified to be reliable by the numerical solutions and experimental measurements of animal locomotion. The results obtained in this study provide physical insight into the understanding of the dynamic mechanisms relevant to flapping locomotion.
Stokes flow singularity at the junction between impermeable and porous walls
Authors: Nitsche Ludwig C. , Parthasarathi Prashanth 
Published: November 2012

AbstractFor two-dimensional, creeping flow in a half-plane, we consider the singularity that arises at an abrupt transition in permeability from zero to a finite value along the wall, where the pressure is coupled to the seepage flux by Darcy’s law. This problem represents the junction between the impermeable wall of the inflow section and the porous membrane further downstream in a spiral-wound desalination module. On a macroscopic, outer length scale the singularity appears like a jump discontinuity in normal velocity, characterized by a non-integrable$1/ r$divergence of the pressure. This far-field solution is imposed as the boundary condition along a semicircular arc of dimensionless radius 30 (referred to the microscopic, inner length scale). A preliminary numerical solution (using a least-squares variant of the method of fundamental solutions) indicates a continuous normal velocity along the wall coupled with a weaker$1/ \sqrt{r} $singularity in the pressure. However, inconsistencies in the numerically imposed outer boundary condition indicate a very slow radial decay. We undertake asymptotic analysis to: (i) understand the radial decay behaviour; and (ii) find a more accurate far-field solution to impose as the outer boundary condition. Similarity solutions (involving a stream function that varies like some power of$r$) are insufficient to satisfy all boundary conditions along the wall, so we generalize these by introducing linear and quadratic terms in$\log r$. By iterating on the wall boundary conditions (analogous to the method of reflections), the outer asymptotic series is developed through second order. We then use a hybrid computational scheme in which the numerics are iteratively patched to the outer asymptotics, thereby determining two free coefficients in the latter. We also derive an inner asymptotic series and fit its free coefficient to the numerics at$r= 0. 01$. This enables evaluation of the singular flow field in the limit as$r\ensuremath{\rightarrow} 0$. Finally, a uniformly valid fit is obtained with analytical formulas. The singular flow field for a solid–porous abutment and the general Stokes flow solutions obtained in the asymptotic analysis are programmed in Fortran for future use as local basis functions in computational schemes. Numerics are required for the intermediate-$r$regime because the inner and outer asymptotic expansions do not extend far enough toward each other to enable rigorous asymptotic matching. The logarithmic correction terms explain why the leading far-field solution (used in the preliminary numerics) was insufficient even at very large distances.
Linear biglobal analysis of Rayleigh–Bénard instabilities in binary fluids with and without throughflow
Authors: Hu Jun , Henry Daniel , Yin Xie-Yuan , BenHadid Hamda 
Published: November 2012

AbstractThree-dimensional Rayleigh–Bénard instabilities in binary fluids with Soret effect are studied by linear biglobal stability analysis. The fluid is confined transversally in a duct and a longitudinal throughflow may exist or not. A negative separation factor $\psi = \ensuremath{-} 0. 01$, giving rise to oscillatory transitions, has been considered. The numerical dispersion relation associated with this stability problem is obtained with a two-dimensional Chebyshev collocation method. Symmetry considerations are used in the analysis of the results, which allow the classification of the perturbation modes as ${S}_{l} $ modes (those which keep the left–right symmetry) or ${R}_{x} $ modes (those which keep the symmetry of rotation of $\lrm{\pi} $ about the longitudinal mid-axis). Without throughflow, four dominant pairs of travelling transverse modes with finite wavenumbers $k$ have been found. Each pair corresponds to two symmetry degenerate left and right travelling modes which have the same critical Rayleigh number ${\mathit{Ra}}_{c} $. With the increase of the duct aspect ratio $A$, the critical Rayleigh numbers for these four pairs of modes decrease and closely approach the critical value ${\mathit{Ra}}_{c} = 1743. 894$ obtained in a two-dimensional situation, one of the mode (a ${S}_{l} $ mode called mode A) always remaining the dominant mode. Oscillatory longitudinal instabilities ($k\approx 0$) corresponding to either ${S}_{l} $ or ${R}_{x} $ modes have also been found. Their critical curves, globally decreasing, present oscillatory variations when the duct aspect ratio $A$ is increased, associated with an increasing number of longitudinal rolls. When a throughflow is applied, the symmetry degeneracy of the pairs of travelling transverse modes is broken, giving distinct upstream and downstream modes. For small and moderate aspect ratios $A$, the overall critical Rayleigh number in the small Reynolds number range studied is only determined by the upstream transverse mode A. In contrast, for larger aspect ratios as $A= 7$, different modes are successively dominant as the Reynolds number is increased, involving both upstream and downstream transverse modes A and even the longitudinal mode.