bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prognosis for Functional Deterioration and Functional Improvement in Late Life Among Community‐Dwelling Persons
Authors: Stineman Margaret G. , Zhang Guangyu , Kurichi Jibby E. , Zhang Zi , Streim Joel E. , Pan Qiang , Xie Dawei 
Published: February 2013

ObjectiveTo examine how health‐related, socioeconomic, and environmental factors combine to influence the onset of activity of daily living (ADL) limitations or prognosis for death or further functional deterioration or improvement among elderly people.DesignA national representative sample with 2‐year follow‐up.SettingCommunity‐dwelling people.ParticipantsIncluded were 9447 persons (≥70 years of age) in the United States from the Second Longitudinal Study of Aging who were interviewed in 1994, 1995, or 1996.MethodsSelf‐ or proxy‐reported health conditions, ADLs expressed as 5 stages describing severity and pattern of limitations, and other baseline characteristics were obtained. A multinomial logistic regression model was used to predict stage transitions. Because of incomplete follow‐up (17.7% of baseline sample), primary analyses were determined by multiple imputation to address potential bias associated with loss to follow‐up.Main Outcome MeasurementADL stage transitions in 2 years (death, deteriorated, stable, and improved ADL function).ResultsIn the imputed‐case analysis, the percentages for those who died, deteriorated, were stable, and improved were 12.6%, 32.7%, 48.4%, and 6.2%, respectively. Persons at a mild stage of ADL limitation were most likely to deteriorate further. Persons at advanced stages were most likely to die. Married people and high school graduates had a lower likelihood of deterioration. The risk of mortality and functional deterioration increased with age. Certain conditions, such as diabetes, were associated both with mortality and functional deterioration; other conditions, such as cancer, were associated with mortality only, and arthritis was associated only with functional deterioration.ConclusionsAlthough overlap occurs, different clinical traits are associated with mortality, functional deterioration, and functional improvement. ADL stages might aid physical medicine and rehabilitation clinicians and researchers in developing and monitoring disability management strategies targeted to maintaining and enhancing self‐care among community‐dwelling older people.
The Prevalence of Fluid Associated With the Iliotibial Band in Asymptomatic Recreational Runners: An Ultrasonographic Study
Authors: Jelsing Elena J. , Finnoff Jonathan , Levy Bruce , Smith Jay 
Published: February 2013

ObjectiveTo evaluate the prevalence and distribution of fluid associated with the iliotibial band (ITB) in asymptomatic recreational runners.DesignProspective cohort study.SettingSports medicine center at a tertiary medical center.PatientsFive male and 15 female asymptomatic recreational runners (10‐30 miles per week) ages 18‐40 years.MethodsParticipants were examined with the use of ultrasonography to assess for the presence of fluid at the level of the lateral femoral epicondyle and determine its relationship to the ITB at 0 and 30° of knee flexion in both supine (non–weight‐bearing) and standing (weight‐bearing) positions.ResultsFluid was associated with the ITB in 100% of asymptomatic recreational runners and was bilateral in 90%. When examined in full extension with the subject supine, fluid was seen in 67.5% of knees (n = 40) compared with 95% of the knees when standing. When examined in 30° of flexion, the presence of fluid decreased to 30% when supine and 22.5% when standing. With the knee in full extension in a supine/standing position, fluid was located anterior and deep 70%/74% of the time and was anterior only 11%/0% of the time. With the knee flexed to 30° in a supine/standing position, fluid was located anterior and deep 50%/33% of the time and anterior only 33%/67% of the time.ConclusionThe prevalence of fluid associated with the ITB varied with body and knee position, was most common in the standing position with the knee extended, and was generally located anterior or anterior and deep to the ITB. The clinical significance of our findings are 2‐fold: (1) body position should be considered when searching for fluid in the vicinity of the ITB, and (2) clinicians and imagers should exercise caution when interpreting the clinical significance of fluid associated with the ITB during ultrasonographic evaluation of runners with lateral knee pain.
Initial growth of a disturbance in a boundary layer influenced by a circular cylinder wake
Authors: He Guosheng , Wang Jinjun , Pan Chong 
Published: February 2013

AbstractThe initial growth of a disturbance induced by a near-wall circular cylinder in a flat-plate boundary layer is experimentally investigated using both particle image velocimetry and hydrogen bubble visualization techniques. The secondary spanwise vortices appear in the near-wall region as a direct response to the outside passing wake vortices, consistent with previous studies on similar models (Pan et al., J. Fluid Mech., vol. 603, 2008, pp. 367–389; Mandal & Dey, J. Fluid Mech., vol. 684, 2011, pp. 60–84). The streamwise variation of the total disturbance energy within the boundary layer shows a two-stage growth, which characterizes the initial transition process: the first exponential growth stage, followed by a region with slower growth rate. It is revealed that these two stages of growth are related to the formation and the destabilization of the secondary vortex in the near-wall region. The technique of dynamic mode decomposition is used to decompose the total disturbance into temporally orthogonalized modes, and it shows that the first growth stage largely results from the increased disturbance at the same frequency as that of the wake vortex shedding, while the second growth stage comprises the disturbance growth in a number of frequencies, especially the lower ones.
Stability of a liquid ring on a substrate
Authors: González Alejandro G. , Diez Javier A. , Kondic Lou 
Published: February 2013

AbstractWe study the stability of a viscous incompressible fluid ring on a partially wetting substrate within the framework of long-wave theory. We discuss the conditions under which a static equilibrium of the ring is possible in the presence of contact angle hysteresis. A linear stability analysis (LSA) of this equilibrium solution is carried out by using a slip model to account for the contact line divergence. The LSA provides specific predictions regarding the evolution of unstable modes. In order to describe the evolution of the ring for longer times, a quasi-static approximation is implemented. This approach assumes a quasi-static evolution and takes into account the concomitant variation of the instantaneous growth rates of the modes responsible for either collapse of the ring into a single central drop or breakup into a number of droplets along the ring periphery. We compare the results of the LSA and the quasi-static model approach with those obtained from nonlinear numerical simulations using a complementary disjoining pressure model. We find remarkably good agreement between the predictions of the two models regarding the expected number of drops forming during the breakup process.
Skin friction on a moving wall and its implications for swimming animals
Authors: Ehrenstein Uwe , Eloy Christophe 
Published: February 2013

AbstractEstimating the energetic costs of undulatory swimming is important for biologists and engineers alike. To calculate these costs it is crucial to evaluate the drag forces originating from skin friction. This topic has been controversial for decades, some claiming that animals use ingenious mechanisms to reduce the drag and others hypothesizing that undulatory swimming motions induce a drag increase because of the compression of the boundary layers. In this paper, we examine this latter hypothesis, known as the ‘Bone–Lighthill boundary-layer thinning hypothesis’, by analysing the skin friction in different model problems. First, we study analytically the longitudinal drag on a yawed cylinder in a uniform flow by using the approximation of the momentum equations in the laminar boundary layers. This allows us to demonstrate and generalize a result first observed semi-empirically by G.I. Taylor in the 1950s: the longitudinal drag scales as the square root of the normal velocity component. This scaling arises because the fluid particles accelerate as they move around the cylinder. Next we propose an analogue two-dimensional problem where the same scaling law is recovered by artificially accelerating the flow in a channel of finite height. This two-dimensional problem is then simulated numerically to assess the robustness of the analytical results when inhomogeneities and unsteadiness are present. It is shown that spatial or temporal changes in the normal velocity usually tend to increase the skin friction compared with the ideal steady case. Finally, these results are discussed in the context of swimming energetics. We find that the undulatory motions of swimming animals increase their skin friction drag by an amount that closely depends on the geometry and the motion. For the model problem considered in this paper the increase is of the order of 20 %.
Contact lines with a contact angle
Authors: Benilov E. S. , Vynnycky M. 
Published: February 2013

AbstractThis work builds on the foundation laid by Benney & Timson (Stud. Appl. Maths, vol. 63, 1980, pp. 93–98), who examined the flow near a contact line and showed that, if the contact angle is $18{0}^{\circ } $, the usual contact-line singularity does not arise. Their local analysis, however, does not allow one to determine the velocity of the contact line and their expression for the shape of the free boundary involves undetermined constants. The present paper considers two-dimensional Couette flows with a free boundary, for which the local analysis of Benney & Timson can be complemented by an analysis of the global flow (provided that the slope of the free boundary is small, so the lubrication approximation can be used). We show that the undetermined constants in the solution of Benney & Timson can all be fixed by matching the local and global solutions. The latter also determines the contact line’s velocity, which we compute among other characteristics of the global flow. The asymptotic model derived is used to examine steady and evolving Couette flows with a free boundary. It is shown that the latter involve brief intermittent periods of rapid acceleration of contact lines.
Self-similar mean dynamics in turbulent wall flows
Authors: Klewicki J. C. 
Published: February 2013

AbstractThis study investigates how and why dynamical self-similarities emerge with increasing Reynolds number within the canonical wall flows beyond the transitional regime. An overarching aim is to advance a mechanistically coherent description of turbulent wall-flow dynamics that is mathematically tractable and grounded in the mean dynamical equations. As revealed by the analysis of Fife, Klewicki & Wei (J. Discrete Continuous Dyn. Syst.A, vol. 24, 2009, pp. 781–807), the equations that respectively describe the mean dynamics of turbulent channel, pipe and boundary layer flows formally admit invariant forms. These expose an underlying self-similar structure. In all cases, two kinds of dynamical self-similarity are shown to exist on an internal domain that, for all Reynolds numbers, extends from$O(\nu / {u}_{\tau } )$to$O(\delta )$, where$\nu $is the kinematic viscosity,${u}_{\tau } $is the friction velocity and$\delta $is the half-channel height, pipe radius, or boundary layer thickness. The simpler of the two self-similarities is operative on a large outer portion of the relevant domain. This self-similarity leads to an explicit analytical closure of the mean momentum equation. This self-similarity also underlies the emergence of a logarithmic mean velocity profile. A more complicated kind a self-similarity emerges asymptotically over a smaller domain closer to the wall. The simpler self-similarity allows the mean dynamical equation to be written as a closed system of nonlinear ordinary differential equations that, like the similarity solution for the laminar flat-plate boundary layer, can be numerically integrated. The resulting similarity solutions are demonstrated to exhibit nearly exact agreement with direct numerical simulations over the solution domain specified by the theory. At the Reynolds numbers investigated, the outer similarity solution is shown to be operative over a domain that encompasses${\sim }40\hspace{0.167em} \% $of the overall width of the flow. Other properties predicted by the theory are also shown to be well supported by existing data.
A simple constitutive model for predicting the pressure histories developed behind rigid porous media impinged by shock waves
Authors: Ram O. , Sadot O. 
Published: February 2013

AbstractShock wave attenuation by means of rigid porous media is often applied when protective structures are dealt with. The passage of a shock wave through a layer of porous medium is accompanied by diffractions and viscous effects that attenuate and weaken the transmitted shock, thus reducing the load that develops on the target wall that is placed behind the protective layer. In the present study, the parameters governing the pressure build-up on the target wall are experimentally investigated using a shock tube facility. Different porous samples are impinged by normal shock waves of various strengths and the subsequent pressure histories that are developed on the target wall are recorded. In addition, different standoff distances from the target wall are investigated. Assuming that the flow through the porous medium is close to being isentropic enabled us to develop a general constitutive model for predicting the pressure history developed on the target wall. This model can be applied to predict the pressure build-up on the target wall for any pressure history that is imposed on the front face of the porous sample without the need to conduct numerous experiments. Results obtained by other investigators are found to be in very good agreement with the predictions of the presently developed constitutive model.
Wall effects on pressure fluctuations in turbulent channel flow
Authors: Gerolymos G. A. , Sénéchal D. , Vallet I. 
Published: February 2013

AbstractThe purpose of the present paper is to study the influence of wall echo on pressure fluctuations${p}^{\prime } $, and on statistical correlations containing${p}^{\prime } $, namely, redistribution${\phi }_{ij} $, pressure diffusion${ d}_{ij}^{(p)} $and velocity pressure-gradient${\Pi }_{ij} $. We extend the usual analysis of turbulent correlations containing pressure fluctuations in wall-bounded direct numerical simulations (Kim,J. Fluid Mech., vol. 205, 1989, pp. 421–451), separating${p}^{\prime } $not only into rapid${ p}_{(r)}^{\prime } $and slow${ p}_{(s)}^{\prime } $parts (Chou,Q. Appl. Maths, vol. 3, 1945, pp. 38–54), but also further into volume (${ p}_{(r; \mathfrak{V})}^{\prime } $and${ p}_{(s; \mathfrak{V})}^{\prime } $) and surface (wall echo,${ p}_{(r; w)}^{\prime } $and${ p}_{(s; w)}^{\prime } $) terms. An algorithm, based on a Green’s function approach, is developed to compute the above splittings for various correlations containing pressure fluctuations (redistribution, pressure diffusion, velocity pressure-gradient), in fully developed turbulent plane channel flow. This exact analysis confirms previous results based on a method-of-images approximation (Manceau, Wang & Laurence,J. Fluid Mech., vol. 438, 2001, pp. 307–338) showing that, at the wall,${ p}_{(\mathfrak{V})}^{\prime } $and${ p}_{(w)}^{\prime } $are usually of the same sign and approximately equal. The above results are then used to study the contribution of each mechanism to the pressure correlations in low-Reynolds-number plane channel flow, and to discuss standard second-moment-closure modelling practices.
Viscous boundary layer properties in turbulent thermal convection in a cylindrical cell: the effect of cell tilting
Authors: Wei Ping , Xia Ke-Qing 
Published: February 2013

AbstractWe report an experimental study of the properties of the velocity boundary layer in turbulent Rayleigh–Bénard convection in a cylindrical cell. The measurements were made at Rayleigh numbers $\mathit{Ra}$ in the range $2. 4\times 1{0}^{8} \lt \mathit{Ra}\lt 5. 6\times 1{0}^{9} $ and were conducted with the convection cell tilted with an angle $\theta $ relative to gravity, at $\theta = 0. 5, 1. 0, 2. 0$ and $3. {4}^{\circ } $, respectively. The fluid was water with Prandtl number $\mathit{Pr}= 5. 3$. It is found that at small tilt angles ($\theta \leq {1}^{\circ } $), the measured viscous boundary layer thickness ${\delta }_{v} $ scales with the Reynolds number $\mathit{Re}$ with an exponent close to that for a Prandtl–Blasius (PB) laminar boundary layer, i.e. ${\delta }_{v} \sim {\mathit{Re}}^{- 0. 46\pm 0. 03} $. For larger tilt angles, the scaling exponent of ${\delta }_{v} $ with $\mathit{Re}$ decreases with $\theta $. The normalized mean horizontal velocity profiles measured at the same tilt angle but with different $\mathit{Ra}$ are found to have an invariant shape. However, for different tilt angles, the shape of the normalized profiles is different. It is also found that the Reynolds number $\mathit{Re}$ based on the maximum mean horizontal velocity scales with $\mathit{Ra}$ as $\mathit{Re}\sim {\mathit{Ra}}^{0. 43} $ and the Reynolds number ${\mathit{Re}}_{\sigma } $ based on the maximum root mean square velocity scales with $\mathit{Ra}$ as ${\mathit{Re}}_{\sigma } \sim {\mathit{Ra}}^{0. 55} $. Within the measurement resolution neither exponent depends on the tilt angle $\theta $. Several wall quantities are also measured directly and their dependencies on $\mathit{Re}$ are found to agree well with those predicted for a classical laminar boundary layer. These are the wall shear stress $\tau $ (${\sim }{\mathit{Re}}^{1. 46} $), the viscous sublayer ${\delta }_{w} $ (${\sim }{\mathit{Re}}^{0. 75} $), the friction velocity ${u}_{\tau } $ (${\sim }{\mathit{Re}}^{- 0. 86} $) and the skin friction coefficient ${c}_{f} $ (${\sim }{\mathit{Re}}^{- 0. 46} $). Again, all of these near-wall quantities do not exhibit a dependence on the tilt angle within the measurement resolution. We also examined the dynamical scaling method proposed by Zhou and Xia (Phys. Rev. Lett., vol. 104, 2010, p. 104301) and found that in both the laboratory and the dynamical frames the mean velocity profiles show deviations from the theoretical PB profile, with the deviations increasing with $\mathit{Ra}$. However, profiles obtained from dynamical scaling in general have better agreement with the theoretical profile. It is also found that the effectiveness of this method appears to be independent of $\mathit{Ra}$.
The Justiciability of Socio-Economic Rights in Botswana
Authors: Dinokopila Bonolo Ramadi 
Published: February 2013

AbstractThe judicial enforcement of socio-economic rights remains a challenge in many countries. This is generally attributable to the inadequacy of a particular country's legal framework, in particular its constitutional framework. Given the importance of judicial remedies in litigation, in particular public interest litigation, this article considers possibilities for the judicial enforcement of socio-economic rights in Botswana. It discusses the institutional, legal and constitutional framework for the promotion, protection and fulfilment of socio-economic rights in the country. It also tackles the issue of whether the judicial enforcement of socio-economic rights is easily achievable when those rights are not constitutionally entrenched. The article also considers whether the absence of directive principles of state policy within Botswana's Constitution is a hindrance to the judicial enforcement of socio-economic rights in Botswana. Within that context, it highlights the possible means of judicial enforcement of socio-economic rights in Botswana.
White-matter microstructure in previously drug-naive patients with schizophrenia after 6 weeks of treatment
Authors: Wang Q. , Cheung C. , Deng W. , Li M. , Huang C. , Ma X. , Wang Y. , Jiang L. , Sham P. C. , Collier D. A. , Gong Q. , Chua S. E. , McAlonan G. M. , Li T. 
Published: February 2013

BackgroundIt is not clear whether the progressive changes in brain microstructural deficits documented in previous longitudinal magnetic resonance imaging (MRI) studies might be due to the disease process or to other factors such as medication. It is important to explore the longitudinal alterations in white-matter (WM) microstructure in antipsychotic-naive patients with first-episode schizophrenia during the very early phase of treatment when relatively ‘free’ from chronicity.MethodThirty-five patients with first-episode schizophrenia and 22 healthy volunteers were recruited. High-resolution diffusion tensor imaging (DTI) was obtained from participants at baseline and after 6 weeks of treatment. A ‘difference map’ for each individual was calculated from the 6-week follow-up fractional anisotropy (FA) of DTI minus the baseline FA. Differences in Positive and Negative Syndrome Scale (PANSS) scores and Global Assessment of Functioning (GAF) scores between baseline and 6 weeks were also evaluated and expressed as a 6-week/baseline ratio.ResultsCompared to healthy controls, there was a significant decrease in absolute FA of WM around the bilateral anterior cingulate gyrus and the right anterior corona radiata of the frontal lobe in first-episode drug-naive patients with schizophrenia following 6 weeks of treatment. Clinical symptoms improved during this period but the change in FA did not correlate with the changes in clinical symptoms or the dose of antipsychotic medication.ConclusionsDuring the early phase of treatment, there is an acute reduction in WM FA that may be due to the effects of antipsychotic medications. However, it is not possible to entirely exclude the effects of underlying progression of illness.
Negative psychotic symptoms and impaired role functioning predict transition outcomes in the at-risk mental state: a latent class cluster analysis study
Authors: Valmaggia L. R. , Stahl D. , Yung A. R. , Nelson B. , Fusar-Poli P. , McGorry P. D. , McGuire P. K. 
Published: February 2013

BackgroundMany research groups have attempted to predict which individuals with an at-risk mental state (ARMS) for psychosis will later develop a psychotic disorder. However, it is difficult to predict the course and outcome based on individual symptoms scores.MethodData from 318 ARMS individuals from two specialized services for ARMS subjects were analysed using latent class cluster analysis (LCCA). The score on the Comprehensive Assessment of At-Risk Mental States (CAARMS) was used to explore the number, size and symptom profiles of latent classes.ResultsLCCA produced four high-risk classes, censored after 2 years of follow-up: class 1 (mild) had the lowest transition risk (4.9%). Subjects in this group had the lowest scores on all the CAARMS items, they were younger, more likely to be students and had the highest Global Assessment of Functioning (GAF) score. Subjects in class 2 (moderate) had a transition risk of 10.9%, scored moderately on all CAARMS items and were more likely to be in employment. Those in class 3 (moderate–severe) had a transition risk of 11.4% and scored moderately severe on the CAARMS. Subjects in class 4 (severe) had the highest transition risk (41.2%), they scored highest on the CAARMS, had the lowest GAF score and were more likely to be unemployed. Overall, class 4 was best distinguished from the other classes on the alogia, avolition/apathy, anhedonia, social isolation and impaired role functioning.ConclusionsThe different classes of symptoms were associated with significant differences in the risk of transition at 2 years of follow-up. Symptomatic clustering predicts prognosis better than individual symptoms.